**7. Interpretation of MHz-kHz EM precursors in terms of fractal electrodynamics**

Recently, the research area known as "fractal electrodynamics" has been established. This term was first suggested by Jaggard [44,45] to identify the newly emerging branch of research, which combines fractal geometry with Maxwel's theory of electrodynamics. From the laboratory scale to the geophysical scale, fault displacements, fault and fracture trace length, and fracture apertures follow a power-law distribution. Thus a fault shows a fractal pattern: a network of line elements having a fractal distribution in space is formed as the event approaches. However, an active crack or rupture can be simulated as a radiating element. The idea is that a *Fractal EM Geo-Antenna* can be formed as an array of line elements having a fractal distribution on the ground surface as the significant EQ is approached. This idea has been tested in [27]: the precursors are governed by characteristics (e.g., scaling laws, temporal evolution of the spectrum content, broad-band spectrum region, and accelerating emission rate) predicted by fractal electrodynamics. Notice, the fractal tortuous structure can significantly increase the radiated power density, as compared to a single dipole antenna. The tortuous path increases the effective dipole moment, since the path length along the emission is now longer than the Euclidean distance, and thus the possibility to capture these preseismic radiations by aerial antennas.

The fractal dimension of the *fractal EM geo-antenna* associated with the Athens EQ is *D* = 1.2 [27]. Seismological measurements as well as theoretical studies [101,102 and references therein] suggest that a surface trace of a single major fault might be characterized by *D* = 1.2. We clarify that the exponent *D* does not describe the geometrical setting of the rupture faults but it only gives the distribution of rupture fault lengths irrespective of their positions. More information is needed for a full geometrical interpretation of the faults, e.g. the position of the rupture centers.

### **8. The science of EQ prediction should, from the start, be multi-disciplinary**

As it was mentioned in Introduction, EQ's preparatory process has various facets which may be observed before the final catastrophe, thus, a candidate preseismic EM activity should be consistent with other EM precursors or precursors that are imposed by data from other disciplines (Seismology, Infrared Remote Sensing, Synthetic Aperture Radars Interferometry e.t.c.).

#### **8.1 Seismic electric signals**

A well documented type of precursory signals is the so-called seismic electric signals (SES) [103]. They are transient low frequency (< 1*Hz*) electric signals and are consistent with the "pressure stimulated currents model", which suggests that, upon a gradual variation of the pressure (stress) on a solid, transient electric signals are emitted, from the reorientation of

3. Two stong burst-like EM anomalies at 3 and 10 kHz were simultaneously recorded before the EQ occurrence. The first and second anomaly lasted for 12 and 17 hours, respectively, with a cessation of 9 hours. The second anomaly ceased about 9 hours before the EQ. This

Are There Pre-Seismic Electromagnetic Precursors? A Multidisciplinary Approach 233

4. Infrared remote sensing makes use of satellite infrared sensors to detect infrared radiation emitted from the Earth's surface before EQs. A clear increase in the thermal infrared radiation (TIR) over the area around the Athen's EQ epicentre recorded during the last days before the EQ. The appearance of TIR emissions enhances the consideration that the fracture process has

5. Synthetic aperture radars (SAR) are space-borne instruments that emit EM radiation and then record the strength and time delay of the returning signal to produce images of the ground. By combining two or more SAR images of the same area, it is possible to generate elevation maps and surface change maps with unprecedented precision and resolution. This technique is called SAR interferometry. SAR interferometry is becoming a new tool for active tectonics by providing both mm-precision surface change maps spanning periods of days to years and m-precision, high-resolution topographic maps for measuring crustal strain accumulated over longer periods of time. The fault modelling of the Athens EQ, based on information obtained by radar interferometry (ERS-2 satellite), predicts two faults: the main fault segment is responsible for 80% of the total energy released, with the secondary fault segment for the remaining 20%. A recent seismic data analysis carried out by Kikuchi, using the now standard methodology, also indicates that a two-event solution for the Athens EQ is more likely than a single event solution. According to Kikuchi, there was probably a subsequent (*M* = 5.5) EQ after about 3.5 s of the main event (*M* = 5.8). On the other hand, two strong impulsive kHz EM bursts were emerged in the tail of the preseismic EM emission. The first burst contains approximately 20% of the total EM energy received during the emergence of the two bursts, and the second the remaining 80%. The aforementioned surprising correlation in the energy domain between the two strong preseismic kHz EM signals and two faults activated, strongly supports beyond any analysis the hypothesis that

6. A precursory power-law-type acceleration of the seismic energy release has been observed in the case of Athens EQ. The apparent onset of precipitous power-law behaviour began approximately 20 days before the EQ and culminated with the main event appearance,

The aforementioned observed phenomena, support the proposal that *"the science of EQ*

In the last 20 years, the study of complex systems has emerged as a recognized field in its own right, although, a good definition of what a complex system is has proven elusive. Is there a common factor in the seemingly diverse complex phenomena? The answer is yes-they happens in systems consisting of many similar units interacting in a relatively well-defined manner; the field of study of complex systems holds that their dynamics is founded on universal principles that may be used to describe phenomena that are otherwise quite different in nature. When one considers a phenomenon or a thing that is "complex", one generally associates it with something that is *hard to separate, analyze or to solve*. Instead,

**8.4 Universality among various geophysical and biological catastrophic events**

preseismic activity obeys all the requirements of the Section 2.2.

been extended up to the surface layers of the crust in the case of this EQ.

the two strong EM bursts reveal the nucleation of the impending EQ.

disappearing soon afterward.

*prediction should, from the start, be multi-disciplinary!"*

electric dipoles formed due to disorder in the focal area, when approaching a critical pressure. Field and laboratory experience coincide to the point that the transient SES tend to appear earlier in respect to the MHz-kHz EM precursors. In a recent paper, Varotsos et al. [54] report that the occurrence time of a main shock is specified in advance by analyzing in "natural time" the seismicity subsequent to the initiation of the SES activity. This analysis identifies the time when the seismicity approaches the critical state. The authors conclude that, from the time of that critical state, "the main shock was found empirically to follow usually within a few days up to one week". It is important to note that: (i) MHz / kHz EM precursors are emerged from approximately a week up to a few hours before the EQ occurence, namely, when the earth crust is in critical state by means of seismicity. (ii) MHz EM precursors can also be attributed to a phase transition of second order, as it happens for the seismicity preceding main shocks. Bear in mind that, in the frame of the proposed two stage model, MHz EM precursors are rooted in fracture of heterogeneous regime which surrounds the activated fault. The finally emerged kHz EM precursors indicate that the occurrence of the prepared EQ is unavoidable. This scheme, namely, the appearance of SES following by kHz-MHz EM precursory radiations, has been reported before EQs that occurred in Greece [21,25,30,104]. We note that, using Fisher Information and entropy metrics, it has been found that both the organization of the seismicity around the activated fault and the organization of the kHz EM precursors significantly increase as the EQ approaches [105].

#### **8.2 EM anomalies rooted in preseismic LAI-coupling**

A class of precursors is rooted in anomalous propagation of EM signals over epicentral regions due to a pre-seismic Lithosphere-Atmosphere-Ionosphere (LAI)coupling [1 and references therein]. During quiet periods, the daily EM data present a main bay-like behaviour. The records refer to the Earth-ionosphere waveguide propagation of natural EM emissions. Any change in the lower ionosphere due to an induced pre-seismic LAI-coupling may result in significant changes in the signal propagation-received at a station. Therefore, the emergence of an ionospheric EM anomaly is recognized by a strong perturbation of the characteristic bay-like morphology in the chain of daily data. Pulinets et al. [106] have reported that ionospheric precursors within 5 days before the seismic shock are registered in 100% of the cases for EQs with magnitude 6 or larger. Such anomalies have been recorded in Greece [21, 27, 104]. *Importantly, these anomalies were followed by well documented preseismic sequence of MHz and kHz EM activities, while SES appeared earlier*. The EM precursors sourced in the preseismic LAI-coupling and the MHz/kHz EM precursors appear during the last days before the main shock, namely, when the earth crust was in critical state by means of seismicity.

#### **8.3 Precursors imposed by data from other disciplines**

As it was emphasized in Introduction, EQ's preparatory process has various facets which may be observed before the final catastrophe. On September 7, 1999 the catastrophic Athens (Greece) EQ with a magnitude *Mw* = 5.9 occurred. The following sequence of well documented different precursors have been observed [26,29,30,104]:

1. A clear SES activity was recorded.

2. MHz EM anomalies were simultaneously recorded at 41, 54, and 135 MHz on August 29, 1999. These anomalies can be attributed to a phase transition of second order by means of the analysis reported in Section 3.

16 Will-be-set-by-IN-TECH

electric dipoles formed due to disorder in the focal area, when approaching a critical pressure. Field and laboratory experience coincide to the point that the transient SES tend to appear earlier in respect to the MHz-kHz EM precursors. In a recent paper, Varotsos et al. [54] report that the occurrence time of a main shock is specified in advance by analyzing in "natural time" the seismicity subsequent to the initiation of the SES activity. This analysis identifies the time when the seismicity approaches the critical state. The authors conclude that, from the time of that critical state, "the main shock was found empirically to follow usually within a few days up to one week". It is important to note that: (i) MHz / kHz EM precursors are emerged from approximately a week up to a few hours before the EQ occurence, namely, when the earth crust is in critical state by means of seismicity. (ii) MHz EM precursors can also be attributed to a phase transition of second order, as it happens for the seismicity preceding main shocks. Bear in mind that, in the frame of the proposed two stage model, MHz EM precursors are rooted in fracture of heterogeneous regime which surrounds the activated fault. The finally emerged kHz EM precursors indicate that the occurrence of the prepared EQ is unavoidable. This scheme, namely, the appearance of SES following by kHz-MHz EM precursory radiations, has been reported before EQs that occurred in Greece [21,25,30,104]. We note that, using Fisher Information and entropy metrics, it has been found that both the organization of the seismicity around the activated fault and the organization of the kHz EM

A class of precursors is rooted in anomalous propagation of EM signals over epicentral regions due to a pre-seismic Lithosphere-Atmosphere-Ionosphere (LAI)coupling [1 and references therein]. During quiet periods, the daily EM data present a main bay-like behaviour. The records refer to the Earth-ionosphere waveguide propagation of natural EM emissions. Any change in the lower ionosphere due to an induced pre-seismic LAI-coupling may result in significant changes in the signal propagation-received at a station. Therefore, the emergence of an ionospheric EM anomaly is recognized by a strong perturbation of the characteristic bay-like morphology in the chain of daily data. Pulinets et al. [106] have reported that ionospheric precursors within 5 days before the seismic shock are registered in 100% of the cases for EQs with magnitude 6 or larger. Such anomalies have been recorded in Greece [21, 27, 104]. *Importantly, these anomalies were followed by well documented preseismic sequence of MHz and kHz EM activities, while SES appeared earlier*. The EM precursors sourced in the preseismic LAI-coupling and the MHz/kHz EM precursors appear during the last days before the main

shock, namely, when the earth crust was in critical state by means of seismicity.

As it was emphasized in Introduction, EQ's preparatory process has various facets which may be observed before the final catastrophe. On September 7, 1999 the catastrophic Athens (Greece) EQ with a magnitude *Mw* = 5.9 occurred. The following sequence of well

2. MHz EM anomalies were simultaneously recorded at 41, 54, and 135 MHz on August 29, 1999. These anomalies can be attributed to a phase transition of second order by means of the

precursors significantly increase as the EQ approaches [105].

**8.2 EM anomalies rooted in preseismic LAI-coupling**

**8.3 Precursors imposed by data from other disciplines**

1. A clear SES activity was recorded.

analysis reported in Section 3.

documented different precursors have been observed [26,29,30,104]:

3. Two stong burst-like EM anomalies at 3 and 10 kHz were simultaneously recorded before the EQ occurrence. The first and second anomaly lasted for 12 and 17 hours, respectively, with a cessation of 9 hours. The second anomaly ceased about 9 hours before the EQ. This preseismic activity obeys all the requirements of the Section 2.2.

4. Infrared remote sensing makes use of satellite infrared sensors to detect infrared radiation emitted from the Earth's surface before EQs. A clear increase in the thermal infrared radiation (TIR) over the area around the Athen's EQ epicentre recorded during the last days before the EQ. The appearance of TIR emissions enhances the consideration that the fracture process has been extended up to the surface layers of the crust in the case of this EQ.

5. Synthetic aperture radars (SAR) are space-borne instruments that emit EM radiation and then record the strength and time delay of the returning signal to produce images of the ground. By combining two or more SAR images of the same area, it is possible to generate elevation maps and surface change maps with unprecedented precision and resolution. This technique is called SAR interferometry. SAR interferometry is becoming a new tool for active tectonics by providing both mm-precision surface change maps spanning periods of days to years and m-precision, high-resolution topographic maps for measuring crustal strain accumulated over longer periods of time. The fault modelling of the Athens EQ, based on information obtained by radar interferometry (ERS-2 satellite), predicts two faults: the main fault segment is responsible for 80% of the total energy released, with the secondary fault segment for the remaining 20%. A recent seismic data analysis carried out by Kikuchi, using the now standard methodology, also indicates that a two-event solution for the Athens EQ is more likely than a single event solution. According to Kikuchi, there was probably a subsequent (*M* = 5.5) EQ after about 3.5 s of the main event (*M* = 5.8). On the other hand, two strong impulsive kHz EM bursts were emerged in the tail of the preseismic EM emission. The first burst contains approximately 20% of the total EM energy received during the emergence of the two bursts, and the second the remaining 80%. The aforementioned surprising correlation in the energy domain between the two strong preseismic kHz EM signals and two faults activated, strongly supports beyond any analysis the hypothesis that the two strong EM bursts reveal the nucleation of the impending EQ.

6. A precursory power-law-type acceleration of the seismic energy release has been observed in the case of Athens EQ. The apparent onset of precipitous power-law behaviour began approximately 20 days before the EQ and culminated with the main event appearance, disappearing soon afterward.

The aforementioned observed phenomena, support the proposal that *"the science of EQ prediction should, from the start, be multi-disciplinary!"*

#### **8.4 Universality among various geophysical and biological catastrophic events**

In the last 20 years, the study of complex systems has emerged as a recognized field in its own right, although, a good definition of what a complex system is has proven elusive. Is there a common factor in the seemingly diverse complex phenomena? The answer is yes-they happens in systems consisting of many similar units interacting in a relatively well-defined manner; the field of study of complex systems holds that their dynamics is founded on universal principles that may be used to describe phenomena that are otherwise quite different in nature. When one considers a phenomenon or a thing that is "complex", one generally associates it with something that is *hard to separate, analyze or to solve*. Instead,

The appearance of common "pathological" symptoms, i.e, high organization, persistency, and acceleratin energy release accompanies the emergence of kHz EM precursors and seizures [124-126]. More recently, Osorio et al. [127] have shown that a dynamical analogy supported by five scale-free statistics , namely, the Gutenberg-Richter distribution of event sizes, the distribution of interevent intervals, the Omori and inverse Omori laws, and the conditional

Are There Pre-Seismic Electromagnetic Precursors? A Multidisciplinary Approach 235

Strong analogies between the dynamics of kHz EM precursors and that and magnetic storms have been realized. The appearance of common "pathological" symptoms, i.e, high organization, persistency, and accelerating energy release accompanies the emergence of these two crises [128-131]. Moreover, the Tsallis-based energy distribution function (Eq. 5) is able to describe solar events and magnetic storms, as well. The best-fit for this analysis is given by a *q*-parameter value equal 1.82 and 1.84, correspondingly [131]. It is very interesting to observe the similarity in the *q*-values for: (i) seismicities generated in various large geographic areas, (ii) the precursory sequence of "EM-EQs" associated with the activation of a single fault,(iii) solar flares, and (iv) magnetic storms. This experimental evidence could be considered as an indication of universality among various geophysical processes. A unified theory may exist for the ways in which the above mentioned different systems organize themselves to produce

As mentioned in Introduction, a key question debated in the scientific community is: Are there credible EM earthquake precursors? Despite fairly abundant circumstantial evidence, EM precursors have not been adequately accepted as real physical quantities, and there may be legitimate reasons for the critical views. In this contribution we propose a strategy for the study of MHz and kHz EM precursors which concentrates in an appropriately critical spirit,

An anomaly in a recorded time series is defined as a deviation from normal (background) behaviour. In order to develop a quantitative identification of EM precursors, tools of information theory and concepts of entropy are used in order to identify statistical patterns. Entropy and information are seen to be complementary quantities, in a sense: entropy "drops" have as a counterpart information "peaks" in a more ordered state. The seismicity is a critical phenomenon [41,54], thus, it is expected that a significant change in the statistical pattern, namely the appearance of entropy "drops" or information "peaks", represents a deviation from normal behaviour, revealing the presence of an EM anomaly. Several well-known techniques have been applied to extract EM precursors hidden in kHz EM time series: *T*-entropy, Approximate entropy, Fisher Information, Correlation Dimension, R/S analysis, Detrended Fluctuation Analysis, Shannon *n*-block entropies (conditional entropy, entropy of the source, Kolmogorov-Sinai entropy), Tsallis entopy. It is important to note that one cannot find an optimum organization or complexity measure. Thus, a combination of some such quantities which refer to different aspects, such as structural or dynamical properties, is the most promising way. The application of all the above mentioned multidisciplinary statistical procedure [30,33,35,36,69-71] sensitively recognizes and discriminates the candidate kHz EM precursors from the EM background: they are characterized by significantly higher

(i) How can we recognize an EM observation as a pre-seismic one?

waiting time until the next event, is shown to exist between seizures and EQs.

a large geological or biological crisis.

on asking 3 crucial questions:

**9. Conclusions**

we refer to a complex system as one whose phenomenological laws, which describe the global behaviour of the system, are not necessarily directly related to the microscopic laws that regulate the evolution of its elementary parts. The main features of this collective bahaviour are that an individual unit's action is dominated by the influence of its neighbours, the unit behaves differently from the way it would behave on its own; and such systems show ordering phenomena as the units simultaneously change their behaviour to a common pattern [107-109]. Generally, topological disorder within the complex system introduces new, surprising effects, the laws that describe their behaviour are qualitatively different from those that governs its units. Therefore, the description of the entire system's behaviour requires a qualitatively new theory. Interesting principles have been proposed in an attempt to provide such a unified theory. These include self-organization, intermittent criticality, simultaneous existence of many degrees of freedom, self-adaption, rugged energy landscapes, and scaling (for example, power-law dependence) of the parameters and the underlying network of connections.

Empirical evidence has been mounting that supports the possibility that a number of systems arising in disciplines as diverse as physics, biology, engineering, and economics may have certain quantitative features that are intriguingly similar. Picoli et. al. [110] reported similarities between the dynamics of geomagnetic signals and heartbeat intervals. de Arcangelis et al. [111] presented evidence for universality in solar flare and earthquake occurrence. Kossobokov and Keilis-Borok [112] have explored similarities of multiple fracturing on a neutron star and on the Earth, including power-law energy distributions, clustering, and the symptoms of transition to a major rupture. Sornette and Helmstetter [113] have presented occurrence of finite-time singularities in epidemic models of rupture, EQs, and starquakes. Abe and Suzuki [114] have shown that internet shares with EQs common scale-invariant features in its temporal behaviours. Peters et al. [115] have shown that the rain events are analogous to a variety of nonequilibrium relaxation processes in nature such as EQs and avalanches. Fukuda et al. [116] have shown similarities between communication dynamics in the Internet and the automatic nervous system.

A corollary in the study in terms of complexity is that transferring ideas and results from investigators in hitherto disparate areas will cross-fertilize and lead to important new results. Considering the rarity of large surface EQs which occurs on land and subtleties of possible preseismic EM signatures, the study of EM precursors by means of complexity offers new possibilities for their exploration.

Importantly, the strong analogies between the dynamics of EQ and neurobiology have been realized by numerous authors [117-123]. In general, authors have suggested that EQ's dynamics and neurodynamics can be analyzed within similar mathematical frameworks [117-127]. Characteristically, driven systems of interconnected blocks with stick-slip friction capture the main features of EQ process. These models, in addition to simulating the aspects of EQs may also represent the dynamics of neurological networks [117 and references therein]. Hopfield [118] proposed a model for a network of *N* integrate-and-fire neurons. In this model, the dynamical equation of *kth* neuron equation 28 in [118] is based on the Hodgekin-Huxley model for neurodynamics and represents the same kind of mean field limit that has been examined in [123], in connection with EQs.

Recently, it has been shown that a unified approach to catastrophic events-from the normal state of earth / brain to EQ by means of preseismic kHz EM emission/epileptic seizure exists. The appearance of common "pathological" symptoms, i.e, high organization, persistency, and acceleratin energy release accompanies the emergence of kHz EM precursors and seizures [124-126]. More recently, Osorio et al. [127] have shown that a dynamical analogy supported by five scale-free statistics , namely, the Gutenberg-Richter distribution of event sizes, the distribution of interevent intervals, the Omori and inverse Omori laws, and the conditional waiting time until the next event, is shown to exist between seizures and EQs.

Strong analogies between the dynamics of kHz EM precursors and that and magnetic storms have been realized. The appearance of common "pathological" symptoms, i.e, high organization, persistency, and accelerating energy release accompanies the emergence of these two crises [128-131]. Moreover, the Tsallis-based energy distribution function (Eq. 5) is able to describe solar events and magnetic storms, as well. The best-fit for this analysis is given by a *q*-parameter value equal 1.82 and 1.84, correspondingly [131]. It is very interesting to observe the similarity in the *q*-values for: (i) seismicities generated in various large geographic areas, (ii) the precursory sequence of "EM-EQs" associated with the activation of a single fault,(iii) solar flares, and (iv) magnetic storms. This experimental evidence could be considered as an indication of universality among various geophysical processes. A unified theory may exist for the ways in which the above mentioned different systems organize themselves to produce a large geological or biological crisis.

#### **9. Conclusions**

18 Will-be-set-by-IN-TECH

we refer to a complex system as one whose phenomenological laws, which describe the global behaviour of the system, are not necessarily directly related to the microscopic laws that regulate the evolution of its elementary parts. The main features of this collective bahaviour are that an individual unit's action is dominated by the influence of its neighbours, the unit behaves differently from the way it would behave on its own; and such systems show ordering phenomena as the units simultaneously change their behaviour to a common pattern [107-109]. Generally, topological disorder within the complex system introduces new, surprising effects, the laws that describe their behaviour are qualitatively different from those that governs its units. Therefore, the description of the entire system's behaviour requires a qualitatively new theory. Interesting principles have been proposed in an attempt to provide such a unified theory. These include self-organization, intermittent criticality, simultaneous existence of many degrees of freedom, self-adaption, rugged energy landscapes, and scaling (for example, power-law dependence) of the parameters and the underlying network of

Empirical evidence has been mounting that supports the possibility that a number of systems arising in disciplines as diverse as physics, biology, engineering, and economics may have certain quantitative features that are intriguingly similar. Picoli et. al. [110] reported similarities between the dynamics of geomagnetic signals and heartbeat intervals. de Arcangelis et al. [111] presented evidence for universality in solar flare and earthquake occurrence. Kossobokov and Keilis-Borok [112] have explored similarities of multiple fracturing on a neutron star and on the Earth, including power-law energy distributions, clustering, and the symptoms of transition to a major rupture. Sornette and Helmstetter [113] have presented occurrence of finite-time singularities in epidemic models of rupture, EQs, and starquakes. Abe and Suzuki [114] have shown that internet shares with EQs common scale-invariant features in its temporal behaviours. Peters et al. [115] have shown that the rain events are analogous to a variety of nonequilibrium relaxation processes in nature such as EQs and avalanches. Fukuda et al. [116] have shown similarities between communication

A corollary in the study in terms of complexity is that transferring ideas and results from investigators in hitherto disparate areas will cross-fertilize and lead to important new results. Considering the rarity of large surface EQs which occurs on land and subtleties of possible preseismic EM signatures, the study of EM precursors by means of complexity offers new

Importantly, the strong analogies between the dynamics of EQ and neurobiology have been realized by numerous authors [117-123]. In general, authors have suggested that EQ's dynamics and neurodynamics can be analyzed within similar mathematical frameworks [117-127]. Characteristically, driven systems of interconnected blocks with stick-slip friction capture the main features of EQ process. These models, in addition to simulating the aspects of EQs may also represent the dynamics of neurological networks [117 and references therein]. Hopfield [118] proposed a model for a network of *N* integrate-and-fire neurons. In this model, the dynamical equation of *kth* neuron equation 28 in [118] is based on the Hodgekin-Huxley model for neurodynamics and represents the same kind of mean field limit that has been

Recently, it has been shown that a unified approach to catastrophic events-from the normal state of earth / brain to EQ by means of preseismic kHz EM emission/epileptic seizure exists.

dynamics in the Internet and the automatic nervous system.

possibilities for their exploration.

examined in [123], in connection with EQs.

connections.

As mentioned in Introduction, a key question debated in the scientific community is: Are there credible EM earthquake precursors? Despite fairly abundant circumstantial evidence, EM precursors have not been adequately accepted as real physical quantities, and there may be legitimate reasons for the critical views. In this contribution we propose a strategy for the study of MHz and kHz EM precursors which concentrates in an appropriately critical spirit, on asking 3 crucial questions:

(i) How can we recognize an EM observation as a pre-seismic one?

An anomaly in a recorded time series is defined as a deviation from normal (background) behaviour. In order to develop a quantitative identification of EM precursors, tools of information theory and concepts of entropy are used in order to identify statistical patterns. Entropy and information are seen to be complementary quantities, in a sense: entropy "drops" have as a counterpart information "peaks" in a more ordered state. The seismicity is a critical phenomenon [41,54], thus, it is expected that a significant change in the statistical pattern, namely the appearance of entropy "drops" or information "peaks", represents a deviation from normal behaviour, revealing the presence of an EM anomaly. Several well-known techniques have been applied to extract EM precursors hidden in kHz EM time series: *T*-entropy, Approximate entropy, Fisher Information, Correlation Dimension, R/S analysis, Detrended Fluctuation Analysis, Shannon *n*-block entropies (conditional entropy, entropy of the source, Kolmogorov-Sinai entropy), Tsallis entopy. It is important to note that one cannot find an optimum organization or complexity measure. Thus, a combination of some such quantities which refer to different aspects, such as structural or dynamical properties, is the most promising way. The application of all the above mentioned multidisciplinary statistical procedure [30,33,35,36,69-71] sensitively recognizes and discriminates the candidate kHz EM precursors from the EM background: they are characterized by significantly higher

The temporal evolution of a MHz EM precursor, which behaves as a phase transition of second order (see Section 3), reveals transition from the phase from non-directional almost symmetrical cracking distribution to a directional localized cracking zone that includes the backbone of strong asperities (*symmetry breaking*). The identification of the time interval where the *symmetry breaking* is completed indicates that the fracture of heterogeneous system in the focal area has been obstructed along the backbone of asperities that sustain the system: *The siege of strong asperities begins*. However, the prepared EQ will occur if and when the local stress exceeds fracture stresses of asperities. As it is mentioned, the lounge of the kHz EM activity shows the fracture of asperities

Are There Pre-Seismic Electromagnetic Precursors? A Multidisciplinary Approach 237

(iii) How can we identify precursory symptoms in EM observations which signify that the

This is a crucial question. Our results suggest that the appearance of a really seismogenic MHz EM anomaly does not mean that the EQ is unavoidable [28, 29]. The interplay between the heterogeneities and the stress field could be responsible for the observed antipersistent pattern of the precursory MHz EM time series [28, 29]. Indeed, in natural rock at large length scales there are long-range anticorrelations, in the sense that a high value of a rock property, e.g., threshold for breaking is followed by a low value and vice versa. The antipersistent character of the MHz EM time series may reflect the fact that in heterogeneous media, volumes with a low threshold for breaking alternate with much stronger volumes. Crack growth in a heterogeneous medium continues until a much stronger region is encountered. When this happens, crack growth stops while another crack nucleates in a weaker region and so on. Antipersistent behavior implies a set of fluctuations tending to induce stability within the system, i.e., a nonlinear negative feedback, which "kicks" the opening cracks away from extremes. Consequently, heterogeneity could account for the appearance of a stationary-like behavior in the antipersistent MHz part of the prefracture EM time series and thus enable the fracture in highly heterogeneous systems to be described via an analogy with thermal continuous

On the contrary, the lounge of the kHz EM activity is the sign of EQ generation. Accumulated evidence support the hypothesis that the kHz EM emission is originated during the fracture of asperities distributed along the activated fault sustaining the

The burden of this contribution was to describe a plausible scenario for the study of EM precursors which includes a rather strict set of criteria for characterizing a sequence of MHz - kHz EM emissions as a seismogenic one. We emphasize that this scenario has already been applied to precursors associated with significant, i.e., EQs with magnitude larger than 6, surface EQs that occurred on land or near the coast-line in Greece and Italy. It seems to provide a coherent framework which ties together the observed phenomenology of MHz and kHz EM precursors, without obvious internal inconsistencies and without violating the laws

*It might be difficult for someone to accept that such anomalies are indeed seismogenic. However it is even more difficult to prove that they are not. How possible would it be to find a non seismogenic EM*

sustaining the fault.

occurrence of the prepared EQ is unavoidable?

phase transition of second order (see Section 3).

*emission that meets the criteria for such a multidisciplinary scheme?*

system (see Sections 4-7).

of physics.

organization / lower complexity in respect to that of the EM noise in the region of the station. Importantly this pre-seismic EM emission is also characterized by strong persistency [28,29]. The simultaneous appearance of both these two crucial characteristics, i.e., higher organization and persistency, implies that the underlying fracture process is governed by a positive feedback mechanism which is consistent with an anomaly being a precursor of an ensuing catastrophic event.

However, we suggest that any multidisciplinary statistical analysis by itself is not sufficient to characterize an emerged kHz EM anomaly as a pre-earthquake one. Much remains to be done to recognise systematically real pre-seismic EM precursors. The Earth's crust is clearly extremely complex. However, despite its complexity, there are several universally valid scaling relations. From the early work of Mandelbrot, much effort has been put to statistically characterise the resulting fractal surfaces in fracture processes. Fracture surfaces were found to be self-affine following the fractional Brownian motion (fBm) model over a wide range of length scales. Moreover, the spatial roughness of fracture surfaces has been interpreted as a universal indicator of surface fracture, weakly dependent on the nature of the material and on the failure mode. The Hurst Exponent *H* specifies the strength of the irregularity ("roughness") of the surface topography and the value of *H* ∼ 0.7 has been interpreted as a universal indicator of surface fracture, weakly dependent on the nature of the material and the failure mode. Therefore, an important pursuit is to make a quantitative comparison between fractal patterns possibly hidden in an emergent kHz EM anomaly on one hand and universal fractal patterns of fracture surfaces on the other hand: an EM precursor associated with the last stage of EQ generation should behave as a persistent fBm temporal fractal, while the "roughness" of its profile, as it is represented by the Hurst exponent, should be characterized by the value *H* ∼ 0.7. These two universal features of fracture are hidden in the recorded kHz EM precursors (see Section 5).

The self-affine nature of faulting and fracture predicts that the activation of a single fault is a reduced / magnified image of the regional/laboratory seismicity, correspondingly [76]. A fracto-EM precursor rooted in the activation of a single fault should be consistent with the above mentioned requirement. The sequence of kHz "electromagnetic earthquakes" rooted in the activation of a single fault satisfies the aforementioned requirement.

(ii) How can we link an individual EM precursor with a distinctive stage of the earthquake preparation?

An important feature, observed both at laboratory and geophysical scale, is that the MHz radiation precedes the kHz one. The remarkable asynchronous appearance of these precursors indicates that they refer to different stages of EQ preparation process. Moreover, it implies a different mechanism for their origin. Scientists ought to attempt to link the available various EM observations, which appear one after the other, to the consecutive processes occurring in Earth's crust.

The following *two stage model of EQ generation by means of pre-fracture EM activities* has been proposed: The pre-seismic MHz EM emission is thought to be due to the fracture of the highly heterogeneous system that surrounds the family of large high-strength entities distributed along the fault sustaining the system, while the kHz EM radiation is due to the fracture of the aforementioned large high-strength entities themselves [e.g.,28,29,31,34,39].

20 Will-be-set-by-IN-TECH

an anomaly being a precursor of an ensuing catastrophic event.

in the recorded kHz EM precursors (see Section 5).

consecutive processes occurring in Earth's crust.

requirement.

preparation?

[e.g.,28,29,31,34,39].

organization / lower complexity in respect to that of the EM noise in the region of the station. Importantly this pre-seismic EM emission is also characterized by strong persistency [28,29]. The simultaneous appearance of both these two crucial characteristics, i.e., higher organization and persistency, implies that the underlying fracture process is governed by a positive feedback mechanism which is consistent with

However, we suggest that any multidisciplinary statistical analysis by itself is not sufficient to characterize an emerged kHz EM anomaly as a pre-earthquake one. Much remains to be done to recognise systematically real pre-seismic EM precursors. The Earth's crust is clearly extremely complex. However, despite its complexity, there are several universally valid scaling relations. From the early work of Mandelbrot, much effort has been put to statistically characterise the resulting fractal surfaces in fracture processes. Fracture surfaces were found to be self-affine following the fractional Brownian motion (fBm) model over a wide range of length scales. Moreover, the spatial roughness of fracture surfaces has been interpreted as a universal indicator of surface fracture, weakly dependent on the nature of the material and on the failure mode. The Hurst Exponent *H* specifies the strength of the irregularity ("roughness") of the surface topography and the value of *H* ∼ 0.7 has been interpreted as a universal indicator of surface fracture, weakly dependent on the nature of the material and the failure mode. Therefore, an important pursuit is to make a quantitative comparison between fractal patterns possibly hidden in an emergent kHz EM anomaly on one hand and universal fractal patterns of fracture surfaces on the other hand: an EM precursor associated with the last stage of EQ generation should behave as a persistent fBm temporal fractal, while the "roughness" of its profile, as it is represented by the Hurst exponent, should be characterized by the value *H* ∼ 0.7. These two universal features of fracture are hidden

The self-affine nature of faulting and fracture predicts that the activation of a single fault is a reduced / magnified image of the regional/laboratory seismicity, correspondingly [76]. A fracto-EM precursor rooted in the activation of a single fault should be consistent with the above mentioned requirement. The sequence of kHz "electromagnetic earthquakes" rooted in the activation of a single fault satisfies the aforementioned

(ii) How can we link an individual EM precursor with a distinctive stage of the earthquake

An important feature, observed both at laboratory and geophysical scale, is that the MHz radiation precedes the kHz one. The remarkable asynchronous appearance of these precursors indicates that they refer to different stages of EQ preparation process. Moreover, it implies a different mechanism for their origin. Scientists ought to attempt to link the available various EM observations, which appear one after the other, to the

The following *two stage model of EQ generation by means of pre-fracture EM activities* has been proposed: The pre-seismic MHz EM emission is thought to be due to the fracture of the highly heterogeneous system that surrounds the family of large high-strength entities distributed along the fault sustaining the system, while the kHz EM radiation is due to the fracture of the aforementioned large high-strength entities themselves The temporal evolution of a MHz EM precursor, which behaves as a phase transition of second order (see Section 3), reveals transition from the phase from non-directional almost symmetrical cracking distribution to a directional localized cracking zone that includes the backbone of strong asperities (*symmetry breaking*). The identification of the time interval where the *symmetry breaking* is completed indicates that the fracture of heterogeneous system in the focal area has been obstructed along the backbone of asperities that sustain the system: *The siege of strong asperities begins*. However, the prepared EQ will occur if and when the local stress exceeds fracture stresses of asperities. As it is mentioned, the lounge of the kHz EM activity shows the fracture of asperities sustaining the fault.

(iii) How can we identify precursory symptoms in EM observations which signify that the occurrence of the prepared EQ is unavoidable?

This is a crucial question. Our results suggest that the appearance of a really seismogenic MHz EM anomaly does not mean that the EQ is unavoidable [28, 29]. The interplay between the heterogeneities and the stress field could be responsible for the observed antipersistent pattern of the precursory MHz EM time series [28, 29]. Indeed, in natural rock at large length scales there are long-range anticorrelations, in the sense that a high value of a rock property, e.g., threshold for breaking is followed by a low value and vice versa. The antipersistent character of the MHz EM time series may reflect the fact that in heterogeneous media, volumes with a low threshold for breaking alternate with much stronger volumes. Crack growth in a heterogeneous medium continues until a much stronger region is encountered. When this happens, crack growth stops while another crack nucleates in a weaker region and so on. Antipersistent behavior implies a set of fluctuations tending to induce stability within the system, i.e., a nonlinear negative feedback, which "kicks" the opening cracks away from extremes. Consequently, heterogeneity could account for the appearance of a stationary-like behavior in the antipersistent MHz part of the prefracture EM time series and thus enable the fracture in highly heterogeneous systems to be described via an analogy with thermal continuous phase transition of second order (see Section 3).

On the contrary, the lounge of the kHz EM activity is the sign of EQ generation. Accumulated evidence support the hypothesis that the kHz EM emission is originated during the fracture of asperities distributed along the activated fault sustaining the system (see Sections 4-7).

The burden of this contribution was to describe a plausible scenario for the study of EM precursors which includes a rather strict set of criteria for characterizing a sequence of MHz - kHz EM emissions as a seismogenic one. We emphasize that this scenario has already been applied to precursors associated with significant, i.e., EQs with magnitude larger than 6, surface EQs that occurred on land or near the coast-line in Greece and Italy. It seems to provide a coherent framework which ties together the observed phenomenology of MHz and kHz EM precursors, without obvious internal inconsistencies and without violating the laws of physics.

*It might be difficult for someone to accept that such anomalies are indeed seismogenic. However it is even more difficult to prove that they are not. How possible would it be to find a non seismogenic EM emission that meets the criteria for such a multidisciplinary scheme?*

indicating the beginning of further damage in rocks. The existence of Kaiser effect in geological scale can justify the systematically observed absence of EM emission during the aftershocks period. The stress during the aftershocks period does not exceed the maximum

Are There Pre-Seismic Electromagnetic Precursors? A Multidisciplinary Approach 239

The described here results seem to be tolerable, whether the presented ideas will prove to be corrects or disappear as others have remain for the future. However, if we accept the presented suggestions, the absence of EME after the EQ occurrence supports the hypothesis that the launched EQ was the main shock. In any case, the complexity of EQ preparation process is enormous, and thus a huge amount of research is needed before we begin to understand it. There are many outstanding answers that we do not know. Yet it is certain that we have begun to place most of the right questions. And this is perhaps a sign of a latent solution. The Greek poet and Nobel Laureate George Seferis has referred to what the ancient Greek spirit is all

*"The birthplace of this idea is found at the dawn of Greek history. Aeschylus, the ancient Greek playwright, formulated it once and for all: He who steps beyond moderation is a hubrist, i.e. arrogant, and hubris is the greatest evil that can fall upon us. Greek Tragedy throughout is full of symbols of this idea. And the symbol that moves me above all others, this symbol I find in the Persians. Xerxes, the old legend tells us, was defeated because he was a hubrist; because he committed this extraordinary deed:*

For the purpose of this chapter, it would mean committing hubris for scientists who have dedicated themselves to the prognosis of earthquakes to think that they can defeat

[1] Uyeda, S., Nagao, T., and Kamogawa, M.: Short-term earthquake prediction: Current

[2] Geller, R., Jackson, D., Kagan, Y., Mulargia, F.: Earthquakes cannot be predicted,

[3] Wyss, M., Martirosyan, A.: Seismic quiescence before the M7, 1988, Spitak earthquake,

[4] Huang, Q.: Search for reliable precursors: a case study of the seismic quiescence of 2000 western Tottori prefecture earthquake. J. Geophys. Res. 111, B04301, 2006. [5] Huang, Q., Sobolev, G.A., Nagao, T.: Characteristics of the seismic quiescence and activation patterns before the M = 7.2 Kobe earthquake, January 17, 1995,

[6] Kossobokov, V.G., Romashkova, L.L., Keilis-Borok, V.I., Healy, J.H.: Testing earthquake prediction algorithms: statistically significant real-time prediction of the largest earthquakes in the Circum-Pacific, 1992–1997, Phys. Earth Planet. Inter. 111, 187–196, [7] Keilis-Borok, V., Shebalin, P., Gabrielov, A., Turcotte, D.: Reverse detection of short

[8] Bahat, D., Rabinovitch, A., and Frid, V.: Tensile Fracturing in Rocks , Springer, New

[9] Ogawa, T., Oike, K. and Miura, T.; Electromagnetic radiation from rocks. J. Geophys.

term earthquake precursors. Phys. Earth Planet. Inter. 145, 75–85, 2004.

status of seismo-electromagnetics, Tectonophysics 470 205–213, 2009.

previously reached stress level associated with the main shock occurrence.

about:

*he lashed at the sea..."*.

"Eggelados".

**10. References**

York, 2005.

Res. 90, 6245–6249, 1985.

Science 275, 1616–1617, 1997.

Tectonophysics 237, 99–116, 2001.

Armenia. Geophys. J. Int. 134, 329–340, 1998

One of the largest controversial issues of the materials science community is the interpretation of scaling laws on material strength. In particular, an important open question is whether the spatial and temporal complexity of earthquake and fault structures emerges from geometry or from the chaotic behaviour inherent to the nonlinear equations governing the dynamics of these phenomena. The observed scaling laws associated with EQs have led a variety of researchers to the conclusion that these events can be regarded as a type of generalized phase transition, similar to the nucleation and critical phenomena that are observed in thermal and magnetic systems [132]. In spite of this prevailing view, other scientists propose a different argument, purely based on geometry. They conclude that as happened for relativity, geometry could again hold an unexpected and fundamental role [133 ].

Our analysis suggests that we should discriminate two distinct cases: (i) The scaling laws associated with the fracture of the backbone of asperities of a single fault could be a product of the fractal scaling of asperities. Geometry holds a fundamental role of the emergence of fractal scaling laws in phenomena associated with the fracture of asperities. The observed precursory kHz EM emission is such a phenomenon. (ii) The scaling laws associated with the fracture of highly heterogeneous component that surrounds the family of asperities could be attributed to a phase transition of second order. Recent results support the concept that seismicity which preceeds of a significant seismic event is a critical phenomenon, it can be attributed to a phase transition of second order [134]. Moreover, it has been found empirically that main shocks occur a few days up to one week after the appearance of criticality. We recall that the MHz EM precursors also behave as a phase transition of second order, and also emerge from approximately one week up to a few hours before the EQ occurrence. These findings verify that the seismicity and the precursory MHz EM activity are two faces of the same coin. Notice, the persistent kHz EM emission, which is emerged in the tail of the preseismic preseismic EM activity, is a nonequilibrium process without any footprint of an equilibrium thermal phase transition. This process indicates that the system acquires a self-regulating character and to a great degree the property of irreversibility, which is one of the important components of predictive capability. The above mentioned findings suggest reconsidering the interpretation of scaling laws on material strength.

The absence of any EM activity during the EQ occurrence and aftersocks period constitutes a puzzling feature in the study of seismogenic EM precursors. A catastrophic decrease in the elastic modulus just before the final rupture is expected. The appearance of an EM gap in all the frequency bands just before the EQ occurrence might be considered as a hallmark that the expected decrease in the elastic modulus has occurred [28, 29]. So, the existence of a quiescent period may constitute the last clue that a significant seismic event is forthcoming with a considerable probability. On the basis of our study, drawing on both field observations and laboratory experiments on rock fracture, we make the following suggestion concerning the initial and final times for the crucial last stage of the EQ preparation process. The initial point corresponds to the appearance of persistent kHz EM emission. The final point corresponds to the onset of a quiescent period when all precursory EM activities cease. This analysis may point to a possible way of estimating the time to global failure. Certainly, further work in this direction is needed.

Irreversible deformation of rocks is accompanied by the Kaizer effect: if the heterogeneous material is loaded, then unloaded before fracture, and loaded again, only a small number of micro-fractures are detected before attaining the previous load. Micro-fracturing activity increases dramatically as soon as the largest previously experienced stress level are exceeded indicating the beginning of further damage in rocks. The existence of Kaiser effect in geological scale can justify the systematically observed absence of EM emission during the aftershocks period. The stress during the aftershocks period does not exceed the maximum previously reached stress level associated with the main shock occurrence.

The described here results seem to be tolerable, whether the presented ideas will prove to be corrects or disappear as others have remain for the future. However, if we accept the presented suggestions, the absence of EME after the EQ occurrence supports the hypothesis that the launched EQ was the main shock. In any case, the complexity of EQ preparation process is enormous, and thus a huge amount of research is needed before we begin to understand it. There are many outstanding answers that we do not know. Yet it is certain that we have begun to place most of the right questions. And this is perhaps a sign of a latent solution. The Greek poet and Nobel Laureate George Seferis has referred to what the ancient Greek spirit is all about:

*"The birthplace of this idea is found at the dawn of Greek history. Aeschylus, the ancient Greek playwright, formulated it once and for all: He who steps beyond moderation is a hubrist, i.e. arrogant, and hubris is the greatest evil that can fall upon us. Greek Tragedy throughout is full of symbols of this idea. And the symbol that moves me above all others, this symbol I find in the Persians. Xerxes, the old legend tells us, was defeated because he was a hubrist; because he committed this extraordinary deed: he lashed at the sea..."*.

For the purpose of this chapter, it would mean committing hubris for scientists who have dedicated themselves to the prognosis of earthquakes to think that they can defeat "Eggelados".

#### **10. References**

22 Will-be-set-by-IN-TECH

One of the largest controversial issues of the materials science community is the interpretation of scaling laws on material strength. In particular, an important open question is whether the spatial and temporal complexity of earthquake and fault structures emerges from geometry or from the chaotic behaviour inherent to the nonlinear equations governing the dynamics of these phenomena. The observed scaling laws associated with EQs have led a variety of researchers to the conclusion that these events can be regarded as a type of generalized phase transition, similar to the nucleation and critical phenomena that are observed in thermal and magnetic systems [132]. In spite of this prevailing view, other scientists propose a different argument, purely based on geometry. They conclude that as happened for relativity, geometry

Our analysis suggests that we should discriminate two distinct cases: (i) The scaling laws associated with the fracture of the backbone of asperities of a single fault could be a product of the fractal scaling of asperities. Geometry holds a fundamental role of the emergence of fractal scaling laws in phenomena associated with the fracture of asperities. The observed precursory kHz EM emission is such a phenomenon. (ii) The scaling laws associated with the fracture of highly heterogeneous component that surrounds the family of asperities could be attributed to a phase transition of second order. Recent results support the concept that seismicity which preceeds of a significant seismic event is a critical phenomenon, it can be attributed to a phase transition of second order [134]. Moreover, it has been found empirically that main shocks occur a few days up to one week after the appearance of criticality. We recall that the MHz EM precursors also behave as a phase transition of second order, and also emerge from approximately one week up to a few hours before the EQ occurrence. These findings verify that the seismicity and the precursory MHz EM activity are two faces of the same coin. Notice, the persistent kHz EM emission, which is emerged in the tail of the preseismic preseismic EM activity, is a nonequilibrium process without any footprint of an equilibrium thermal phase transition. This process indicates that the system acquires a self-regulating character and to a great degree the property of irreversibility, which is one of the important components of predictive capability. The above mentioned findings suggest reconsidering the interpretation

The absence of any EM activity during the EQ occurrence and aftersocks period constitutes a puzzling feature in the study of seismogenic EM precursors. A catastrophic decrease in the elastic modulus just before the final rupture is expected. The appearance of an EM gap in all the frequency bands just before the EQ occurrence might be considered as a hallmark that the expected decrease in the elastic modulus has occurred [28, 29]. So, the existence of a quiescent period may constitute the last clue that a significant seismic event is forthcoming with a considerable probability. On the basis of our study, drawing on both field observations and laboratory experiments on rock fracture, we make the following suggestion concerning the initial and final times for the crucial last stage of the EQ preparation process. The initial point corresponds to the appearance of persistent kHz EM emission. The final point corresponds to the onset of a quiescent period when all precursory EM activities cease. This analysis may point to a possible way of estimating the time to global failure. Certainly, further work in this

Irreversible deformation of rocks is accompanied by the Kaizer effect: if the heterogeneous material is loaded, then unloaded before fracture, and loaded again, only a small number of micro-fractures are detected before attaining the previous load. Micro-fracturing activity increases dramatically as soon as the largest previously experienced stress level are exceeded

could again hold an unexpected and fundamental role [133 ].

of scaling laws on material strength.

direction is needed.


[27] Eftaxias, K., Frangos, P., Kapiris, P., Polygiannakis, J., Kopanas, J., Peratzakis, A., Skountzos, P., and Jaggard, D.: Review-Model of Pre-Seismic Electromagnetic

Are There Pre-Seismic Electromagnetic Precursors? A Multidisciplinary Approach 241

[31] Eftaxias, K., Sgrigna, V., and Chelidze, T., (Eds): Mechanical and Electromagnetic Phenomena Accompanying Preseismic Deformation: from Laboratory to Geophysical

[32] Papadimitriou, K., Kalimeri, m., and Eftaxias, K.: Nonextensivity and universality in

[33] Kalimeri, M., Papadimitriou, K., Balasis, G., and Eftaxias, K.: Dynamical complexity detection in pre-seismic emissions using nonadditive Tsallis entropy, Physica A, 387,

[34] Contoyiannis, Y., and Eftaxias, K.: Tsallis and Levy statistics in the preparation of an

[35] Eftaxias, K., Athanasopoulou, L., Balasis, G., Kalimeri, M., Nikolopoulos, S., Contoyiannis, Y., Kopanas, J., Antonopoulos, G., and Nomicos, C.: Unfolding the procedure of characterizing recorded ultra low frequency, kHZ and MHz electromagetic anomalies prior to the L'Aquila earthquake as pre-seismic ones. Part

[36] Eftaxias, K., Balasis, G., Contoyiannis, Y., Papadimitriou, C., Kalimeri, M., Kopanas, J., Antonopoulos, G., and Nomicos, C.: Unfolding the procedure of characterizing recorded ultra low frequency, kHZ and MHz electromagnetic anomalies prior to the L'Aquila earthquake as pre-seismic ones. Part II, Nat. Hazards Earth Syst. Sci. 10,

[37] Eftaxias, K., Maggipinto, T., Meister, C-V., and Katz. O (Eds).: Progress in the research on earthquakes precursors, Natural Hazard and Earth System Sciences (Special Issue),

[38] Kossobokov, V.: Testing earthquake prediction methods: the West Pacific short-term forecast of earthquakes with magnitude *MwHRV* > 5.8, Tectonophysics, 413, 25–31,

[39] Contoyiannis, Y., Nomicos, C., Kopanas, J., Antonopoulos, G., Contoyianni , L.,and Eftaxias, K.: Critical features in electromagnetic anomalies detected prior to the

[40] Herrmann, H. J., and Roux, S.: Statistical Physics for the Fracture of Disordered Media,

[41] Sornette, D.: Critical Phenomena in Natural Sciences, Chaos, Fractals, Self-organization and Disorder: Concepts and Tools, Second edition, Springer

[42] Contoyiannis, Y., Diakonos, F., Kapiris, P., Peratzakis, A., and Eftaxias, K.: Intermittent Dynamics of Critical Pre-seismic Electromagnetic Fluctuations, Physics and Chemistry

the earthquake preparation process, Physical Review E, 77, 36101, 2008.

earthquake, Nonlinear Processes in Geophysics, 15, 379–388, 2008.

I, Nat. Hazards Earth Syst. Sci.., 9, 1953–1971, 2009.

L'Aquila earthquake, Physica A 389 , 499-508, 2010.

Emissions in Terms of Fractal-Electrodynamics, Fractals, 12, 243 – 273, 2004. [28] Kapiris, P., Eftaxias, K., Chelidze, T.: Electromagnetic Signature of Prefracture Criticality in Heterogeneous Media, Physical Review Letters, 92(6), 065702, 2004. [29] Contoyiannis, Kapiris, P., and Eftaxias, K.: A Monitoring of a Pre-Seismic Phase from its Electromagnetic Precursors, Physical Review E, 71, 061123-1 – 061123-14, 2005. [30] Karamanos, K., Dakopoulos, D., Aloupis, K., Peratzakis, A., Athanasopoulou, L., Nikolopoulos, S., Kapiris, P., Eftaxias, K.: Study of pre-seismic electromagnetic signals

in terms of complexity. Physical Review E. 74, 016104-1/21, 2006.

Scale, Tectonophysics, 431, 1-301, 2007.

1161-1172-, 2008.

275–294, 2010.

Elsevier, Amsterdam, 1990.

Series in Synergetics, Heidelberg, 2004.

of the Earth, 29, 397 – 408, 2004.

2011.

2006


24 Will-be-set-by-IN-TECH

Eds). Japanese Society for NDI, Nara, Japan: 311–314: 1996.

Physical Mesomechanics, 4, 21-32, 2001.

Phys. D. Appl. Phys. 36, 1620–1628, 2003.

Rock Mech. Rock Eng. 38, 411–423, 2005.

Geophys. Res. 87, 2851-2859, 1982.

J. Geophys. Res. 87, 7824–7828, 1982

Prediction, Terrapub, Tokyo, 1994.

Acad., 76(B), 45-50, 2000.

69/1-69/4, 2002.

with Earthquakes, Terrapub, Tokyo, 1999.

anomalies. Geophys. Res. Let., 28, 3321-3324, 2001.

1995 Kobe earthquake. J. Geodyn. 33, 401–411, 2002.

[10] OŠKeefe, S. G. and Thiel, D. V.; A mechanism for the production of electromagnetic radiation during fracture of brittle materials. Phys. Earth Plant. Inter. 89, 127–135, 1995. [11] Lolajicek, T. and Sikula, J.: Acoustic emission and electromagnetic effects in rocks. In: Progress in Acoustic Emission VIII. Proceedings of the 13th International Acoustic Emission Symposium, 30 November, 1996. (Kishi, T., Mori, Y., Higo, H. and Enoki, M.,

[12] Panin, V., Deryugin, Ye., Hadjicontis, V., Mavromatou, C., and Eftaxias, K.: Scale levels of strain localization and fracture mechanism of LiF single crystals under compression,

[13] Frid, V., Rabinovitch, A. and Bahat, D.: Fracture induced electromagnetic radiation. J.

[14] Mavromatou, C., Hadjicontis, V., Ninos, D. Mastroyiannis, D., Hadjicontis, E., and Eftaxias, K.: Understanding the fracture phenomena in inhomogeneous rock samples and ionic crystals, by monitoring the electromagnetic emission during the

[15] Fukui, K., Okubo, S. and Terashima, T.: Electromagnetic radiation from rock during uniaxial compression testing: the effects of rock characteristics and test conditions.

[16] Lacidogna, G., Carpinteri, A., Manuello, A., Durin, G., Sciavi, A., Niccolini, G., and Agosto, A.: Acoustic and electromagnetic emissions as precursor phenomena in failure

[17] Warwick, J. W., Stoker. C, and Meyer, T. R.: Radio emission associated with rock fracture: possible application to the great Cjilean earthquake of May 22, 1960, J.

[18] Gokhberg, M. B., Morgunov, V. A., Yoshino, T. and Tozawa, I.: Experimental measurement of electromagnetic emissions possibly related to earthquakes in Japan.

[19] Hayakawa, M. and Fujinawa, Y.: Electromagnetic Phenomena Related to Earthquake

[20] Hayakawa, M.: Atmospheric and Ionospheric Electromagnetic Phenomena Associated

[21] Eftaxias, K., Kopanas, J., Bogris, N., Kapiris, K., Antonopoulos, G. and Varotsos P.: Detection of electromagnetic earthquake precursory signals in Greece, Proc. Japan

[22] Eftaxias, K., P. Kapiris, J. Polygiannakis, N. Bogris, J. Kopanas, G. Antonopoulos, A. Peratzakis and V. Hadjicontis.: Signatures of pending earthquake from electromagnetic

[23] Hayakawa, M. and Molchanov, O.: Seismo Electromagnetics, Terrapub, Tokyo, 2002. [24] Nagao, T., Enomoto, Y., Fujinawa, Y. et˘aal.: Electromagnetic anomalies associated with

[25] Eftaxias, K., Kapiris, P., Dologlou, E., Kopanas, J., Bogris, N., Antonopoulos, G., Peratzakis, A., and Hadjicontis, V.: EM anomalies before the Kozani earthquake: A study of their behaviour through laboratory experiments, Geophys. Res. Lett., 29,

[26] Eftaxias, K., Kapiris, P., Polygiannakis, J., Kopanas, J., Antonopoulos, G., and Rigas, D.: Experience of short term earthquake precursors with VLF-VHF electromagnetic

emissions, Natural Hazards and Earth System Sciences, 3, 217-228, 2003.

deformation, Physics and Chemistry of the Earth, 29, 353 – 357, 2004.

processes, Strain 47,1-9, 2011, doi: 10.1111/j.1475-1305.2010.00750.x


[68] Karamanos, K. Peratzakis, A., Kapiris, P., Nikolopoulos, S., Kopanas, J., and Eftaxias, K.: Extracting pre-seismic electromagnetic signatures in terms of symbolic dynamics,

Are There Pre-Seismic Electromagnetic Precursors? A Multidisciplinary Approach 243

[69] Nikolopoulos, S., Kapiris, P., Karamanos K., and Eftaxias, K.: A unified approach of catastrophic events, Natural Hazards and Earth System Sciences, 4, 615-637, 2004 [70] Eftaxias, K., Kapiris, P., Balasis, G., Peratzakis, A., Karamanos, K., Kopanas, J., Antonopoulos, G., and Nomicos, C.: A Unified Approach to Catastrophic Events: From the Normal State to Geological or Biological Shock in Terms of Spectral Fractal and Nonlinear Analysis, Natural Hazards and Earth System Sciences, 6, 205-228, 2006. [71] Eftaxias, K., Minadakis, G., Athanasopoulou. L., Kalimeri. M., Potirakis, S., and Balasis, G.: Are Epileptic Seizures Quakes of the Brain? An Approach by Means of

[72] Sotolongo-Costa, O. and Posadas, A.: Fragment-asperity interaction model for EQ,

[73] Silva, R., Franca, G., Vilar, C., and Alcaniz, J.: Nonextensive models for earthquakes,

[74] Telesca, L.: Tsallis-Based Nonextensive Analysis of the Southern California Seismicity

[75] Eftaxias, K.: Footprints of nonextensive Tsallis statistics, self-affinity and universality in the preparation of the L'Aquila earthquake hidden in a pre-seismic EM emission,

[76] Huang, J., and Turcotte, D.: Fractal distributions of stress and strength and variations

[77] Rabinovitch, A., Frid, V., and Bahat, D.: Gutenberg-Richter-type relation for laboratory fracture-induced electromagnetic radiation, Phys. Rev. E, 65, 11 401/1-11 401/4, 2001. [78] Kapiris, P., Balasis, G., Kopanas, J., Antonopoulos, G., Peratzakis, A., and Eftaxias, K.: Scaling Similarities of Multiple Fracturing of Solid Materials, Nonlinear Proc. Geoph.,

[79] Scholz, C.: The frequency-magnitude relation of macrofracturing in rocks and its

[80] Ponomarev, A. Zavyalov, A., Smirnov, V., and Lockner, D.: Physical modelling of the formation and evolution of seismically active fault zones, Tectonophysics, 277, 57–81,

[81] Lei, X., and Satoh, T.: Indicators of critical point behavior prior to rock failure inferred

[82] Hainzl, S., Zoller, G., and Scherbaum, F.: Earthquake clusters resulting from delayed rupture propagation in finite fault segments, Geophys. Res. Lett., 108, 2013-2016, 2003. [83] Heneghan C., and McDarby, G.: Establishing the relation between detrended fluctuation analysis and power spectral density analysis for stochastic processes, Phys.

[84] Turcotte., D.: Fractals and chaos in geology and geophysics, Cambridge University

[85] Sammis, C. and Sornette, D.: Positive feedback, memory, and the predictability of EQ,

[86] Ponson, L., Bonamy, D., and Bouchaud, E.: Two-dimensional scaling properties of

experimental fracture surfaces, Phys. Rev. Lett., 96, 35506-1/4, 2006.

relation to earthquakes, Bull. Seismo. Soc. Am., 58, 399–415, 1968.

from pre-failure damage, Tectonophysics, 431, 97–111, 2007.

Nonlinear Processes in Geophysics, 12, 835-848, 2005.

Nonextensive Tsallis Statistics (submitted)

of b–value, Earth Planet. Sci. Lett., 91, 223-230, 1988.

Phys. Rev. Lett., 92, 048501, 2004.

Phys. Rev. E, 73, 026102, 1–5, 2006.

Entropy, 13(7), 1267-1280, 2011.

Physica A 389, 133-140, 2009.

11, 137–151, 2004.

Rev. E, 62, 6103–6110, 2000

P. Natl. Acad. Sci. USA, 99, 2501–2508, 2002.

1997.

Press, 1997.


26 Will-be-set-by-IN-TECH

[47] Pulinets, S. and Boyarchuk, K.: Ionospheric Precursors of Earthquakes, Springer, 2005. [48] Ouzounov, D., and Freund, F.: Mid-infrared emission prior to strong earthquakes analyzed by remote sensing data. Advances in Space Research, 33, 268–273, 2004. [49] Rosen, P., Hensley, S., Joughin, I., Li, F., Madsen, S., Rodriguez, E., and Goldstein, R.: Synthetic Aperture Radar Interferometry, Proceedings of the IEEE, 88, 333-382, 2000 [50] Stanley, H.: Scaling, universality, and renormalization: Three pillars of modern critical

[51] Bar-Yam, Y.: Dynamics of complex systems. Reading, Mass., Addison-Wesley, 1997. [52] Contoyiannis, Y. and Diakonos, F.: Criticality and intermittency in the order parameter

[53] Contoyiannis, Y., Diakonos, F., and Malakis, A.: Intermittent dynamics of critical

[54] Varotsos, P., Sarlis, N., Skordas, E., Uyeda, S., and Kamogawa, M.: Natural time

[55] Titchener, M., Nicolescu, R., Staiger, L., Gulliver, A., and Speidel,U.: Deterministic

[58] Hurst, H.: Long term storage capacity of reservoirs, Trans. Am. Soc. Civ. Eng., 116,

[59] Peng, C., Mietus, J., Hausdorff, J., Havlin, S., Stanley, H., and Goldberger, A.: Long-range anticorrelations and non-Gaussian behavior of the heartbeat, Phys. Rev.

[60] Peng, C., Havlin, S., Stanley, H., and Goldberger, A.: Quantification of scaling exponents and crossover phenomena in nonstationary heartbeat timeseries, Chaos, 5,

[61] Shannon, C. E.: A mathematical theory of communication, The Bell System Tech. J., 27,

[62] Ebeling, W. and Nicolis, G.: Word frequency and entropy of symbolic sequences: A

[63] Ebeling, W.: Prediction and entropy of nonlinear dynamical systems and symbolic

[64] Ebeling, W., Steuer, R., and Titchener, M.: Partition-based entropies of deterministic

[65] Ebeling,W.: Entropies and predictability of nonlinear processes and time series, edited

[66] Tsallis, C.: Possible generalization of Boltzmann-Gibbs statistics, J. Stat. Phys., 52,

[67] Tsallis, C.: Introduction to Nonextensive Statistical Mechanics, Approaching a

dynamical Perspective, Chaos, Solitons & Fractals, 2, 635–650, 1992.

and stochastic maps, Stochastics and Dynamics, 1, 45–61, 2001.

by: Sloot, P. M. A., et al., ICCS 2002, LNCS, 1209–1217, 2002

sequences with LRO, Physica D, 109, 42–52, 1997.

[56] Fisher, R.: Theory of statistical estimation, Proc. Camb. Phil. Soc. 22, 700–725, 1925. [57] Grassberger, P. and Procaccia, I.: Characterization of strange attractors, Phys. Rev. Lett.,

analysis of critical phenomena, PNAS, July 12, 108 , 11361–11364, 2011.

[43] Mandelbrot, B.: The Fractal Geometry of Nature, W. H. Freema, New York, 1982. [44] Jaggard, D.: On fractal electrodynamics, in Recent Advances in Electromagnetic Theory, eds. H. Kritikos and D. Jaggard, Springer-Verlag, New York, 183–224, 1990. [45] Jaggard, D., and Frangos, P.: Surfaces and superlattices, in Frontiers in

Electrodynamics, eds. D. Werner and R. Mittra, IEEE Press,1–47, 2000. [46] Varotsos, P.: The Physics of Seismic Electric Signals, TerraPub, Tokyo, 2005.

phenomena, Rev. Mod. Phys., 71, S358– S366, 1999.

fluctuations, Phys. Rev. Lett., 89, 35701– 35704, 2002.

Complexity and Entropy, Fund. Inform., 64, 443–461, 2005.

space, Phys. Lett. A, 268, 286–272, 2000.

50, 346–349, 1983.

Lett., 70, 1343–1346, 1993.

379–423, 623-656, 1948.

770–808, 1951.

82-87, 1995.

479–487, 1988.

Complex Word, Springer, 2009.


[106] Pulinets, S., LegenŠka, A., Gaivoronskaya, T., and Depuev, V: Main phenomenological of ionospheric precursors of strong earthquakes, J. Atmos. Sol.-Terr. Phy., 65,

Are There Pre-Seismic Electromagnetic Precursors? A Multidisciplinary Approach 245

[109] Stanley, H.: Exotic statistical physics: Applications to biology, medicine, and

[110] Picoli, S., Mendes, R., Malacarne, L., Papa, A.: Similarities between the dynamics of geomagnetic signal and heartbeat intervals, Europhysics Letters, 80, 50006/1U6, 2007. ˚ [111] de Arcangelis, L., Godano, C., Lippiello, E., and Nicodemi, M.: Universality in Solar Flare and Earthquake Occurrence, Phys. Rev. Lett., 96, 051102/1–4, 2006. [112] Kossobokov, V., Keillis-Borok, V., and Cheng, B.: Similarities of multiple fracturing on

[113] Sornette, D.: Predictability of catastrophic events: material rupture, earthquakes, turbulence, financial crashes and human birth, Proceedings of the National Academy

[114] Abe, S., and Suzuki, N.: Statistical similarities between internetquakes and

[115] Peters, O., Hertlein, C., and Christensen, K.: A complexity view of rainfall, Phys. Rev.

[116] Fukuda, K., Nunes, L., and Stanley, H.: Similarities between communication dynamics in the Internet and the automatic nervous system, Europhys. Lett., 62, 189–195, 2003. [117] Herz, A. and Hopfield, J.: Earthquake cycles and neural reverberations: Collective oscillations in systems with pulse-coupled threshold elements, Phys. Rev. Lett., 75,

[120] Corral, A., Perez, C., and Diaz-Guilera, A.: Self-organized criticality induced by

[121] Plenz, D.: When inhibition goes incognito: feedback interaction between spiny projection neurons in striatal function, TRENDS in Neurosciences, 26(8), 436–443, 2003. [122] Zhao, X. and Chen, T.: Type of self-organized criticality model based on neural

[123] Rundle, J., Tiampo, K., Klein, W., and Sa Martins, J.: Selforganization in leaky threshold systems: the influence of near mean field dynamics and its implications for EQs,

[124] Nikolopoulos, S., Kapiris, P., Karamanos, K., and Eftaxias, K.: A unified approach of catastrophic events, Natural Hazards and Earth System Sciences, 4, 615-637, 2004. [125] Li, X., Polygiannakis, J., Kapiris, P., Peratzakis, A., Eftaxias, K., and Yao, X.: Fractal spectral analysis of pre-epileptic seizures in terms of criticality, Journal of Neural

[126] Kapiris, P., Polygiannakis, J., Yao, X., and Eftaxias, K.: Similarities in precursory features in seismic shocks and epileptic seizures. Europhysics Letters 69, 657-663, 2005. [127] Osorio, I., Frei, M., Sornette, D., Milton, J., and Lai, Y.: Epileptic seizures: Quakes of

[118] Hopfield, J.: Neurons, dynamics and computation, Phys. Today, 40, 40-46, 1994. [119] Usher, M., Stemmler, M., and Olami, Z.: Dynamic pattern formation leads to 1/ *f* noise

in neural populations, Phys. Rev. Lett., 74, 326–329, 1995.

diversity, Phys. Rev. Lett., 78(8), 1492–1495, 1997.

networks, Phys. Rev. E, 65, 026114-1–026114-6, 2002.

neurology, and forecasting, PNAS, 99, 2514–2521, 2002.

[107] Vicsek, T.: A question of scale, Nature, 411, 421 pp., 2001. [108] Vicsek, T.: The bigger picture, Nature, 418, 131 pp., 2002.

a neutron star and on Earth, Phys. Rev. E, 61, 3529–3533, 2000.

economics, Physica A, 285, 1-17, 2000.

of Sciences USA, 99, 2522–2529, 2002.

Lett. 88, 018701, 2002.

1222-1225, 1995.

Engineering 2, 1-6, 2005.

the brain? Phys. Rev. E. 82, 021919, 2010.

earthquakes, Physica D 193, 310-314, 2004.

1337–1347, 2003.


28 Will-be-set-by-IN-TECH

[87] Mourot, G., Morel, S., Bouchaud, E., and Valentin, G.: Scaling properties of mortar

[88] Lopez, J., and Schmittbuhl, J.: Anomalous scaling of fracture surfaces, Phys. Rev. E, 57,

[89] Zapperi, S., Kumar, P., Nukala, V., and Simunovic, S.: Crack roughness and avalanche

[90] Hansen, A., and Schmittbuhl, J.: Origin of the universal roughness exponent of brittle fracture surfaces:stress-weighted percolation in the damage zone, Phys. Rev. Lett., 90,

[91] Renard, F., Voisin, C., Marsan, D., and Schmittbuhl, J.: High resolution 3D laser scanner measurements of a strike-slip fault quantity its morphological anisotropy at all scales,

[92] Sornette, D., Helmstetter, A.: Occurrence of finite-time singularities in epidemic models of rupture, earthquakes and starquakes, Phys. Rev. Lett. 89 (15), 158501, 2002. [93] Sornette, D., Sammis, C.: Complex critical exponents from renormalization group theory of earthquakes: Implications for earthquake predictions, J. Phys. I 5, 607–619,

[94] Sornette, D., Vanneste, C.: Dynamics and memory effects in rupture of thermal fuse

[95] Sornette, D., Vanneste, C., Knopoff, L.: Statistical model of earthquake foreshocks,

[96] Bowman, D., Ouillon, G., Sammis, C., Sornette, A., and Sornette, D.: An observational test of the critical earthquake concept, J. Geophys. Res., 103, 24359-24372, 1998. [97] Bowman, D. and King, G.: Accelerating seismicity and stress accumulation before

[98] Bufe, C. and Varnes, D.: Predictive modelling of the seismic cycle of the greater San

[99] S. C. Jaume and L. R. Sykes, Evolving towards a critical point: a review of accelerating seismic moment/energy release prior to large and great earthquakes, Pure Appl.

[100] Sahimi, M.: Flow phenomena in rocks: from continuum models to fractals, percolation, cellular automata, and simulated annealing, Rev. Mod. Phys., 65, 1393–1534, 1993. [101] Sahimi, M., Robertson, M., and Sammis, C.: Fractal distribution of earthquakes hypocenters and its relation to fault patterns and percolation, Phys. Rev. Lett., 70,

[102] Sornette, D.: Self-organized criticality in plate tectonics, in: Spontaneous Formation of Space-Time Sructures and Criticality, edited by Riste, T. and Sherrington, D., 57–106,

[104] Kapiris, P., Nomicos, K., Antonopoulos, G., Polygiannakis, J., Karamanos, K., Kopanas, J., Zissos, A., Peratzakis, A., and Eftaxias, K.: Distinguished seismological and electromagnetic features of the impending global failure: did the 7/9/1999 M5.9 Athens earthquake come with a warning? Earth Planets and Space, 57, 215-230, 2005. [105] Potirakis, S., Minadakis, G., Eftaxias, K.: Fisher information measure, Tsallis entropy, Symbolic dynamics, Fracture induced electromagnetic emissions, Physica A, (in press).

[103] Varotsos, P.: The Physics of Seismic Electric Signals, TerraPub, Tokyo, 2005.

large Earthquakes, J. Geophys. Res. Lett., 28(21), 4039–4042, 2001.

Francisco Bay region, J. Geophys. Res., 98, 9871–9883, 1993.

precursors in the random fuse model, Phys. Rev. E, 71, 26106/1–10, 2005.

fracture surfaces, Int. J. of Fracture, 140, 39–54, 2006.

6405-6408, 1998.

45504–45507, 2003.

1995.

Geophys. Res. Lett., 33, L04305, 2006.

networks, Phys. Rev. Lett. 68, 612–615, 1992.

Phys. Rev. A 45, 8351–8357.

Geophys. 115 (1999) 279–305.

Kluwer Academic Publishers, 1991.

2186–2189, 1993.


**12** 

Nuray Balkis

*Turkey* 

**The Effect of Marmara (Izmit) Earthquake on** 

 **the Chemical Oceanography and Mangan** 

*Istanbul University, Marine Science and Management Institute, Istanbul* 

Dissolved oxygen (DO) content of the marine environment is a crucial parameter for life and water quality as well as playing an important role in biogeochemical processes, and respiration of plants and animals, and decomposition of organic matter by bacteria are the primary processes that consume dissolved oxygen content of water and pore-water in sediments. If the oxygen concentration of water falls below about 2 mg/1, living organisms become stressed and the consequent conditions lead to hypoxia. Persistent hypoxia and increased oxygen uptake accompanies release of hydrogen sulfide. Anoxia occurs in estuaries where high loads of organic matter and/or nutrients are supplied, and in semienclosed water bodies where water mixing and tidal exchanges are strongly restricted. In recent years, aquatic ecosystems have been contaminated by heavy metals; which are of agricultural, industrial, domestic, mining and also natural origins (Ayas and Kolankaya 1996; Han et al., 2002). They are potentially toxic to the aquatic environment; if they exceed natural limits, they will be harmful to the aquatic organisms' environments and human health (Forstner and Witmann, 1981). Organisms need some metals such as Fe, Cu, Zn, Co, Se, Ni and Mn in certain amounts; however, exceeding these amounts may cause toxic effects for these organisms. Some metals such as Hg, Cr, Pb and Cd are toxic to organisms and marine habitat. These metals are dissolved in sea water or suspended in solid materials and absorbed through the gills or skin of marine organisms; they also accumulate in the bodies of organisms through the food chain (Forstner and Witmann, 1981). Mussels, in particular, have been used as biological indicator organisms to monitor marine pollution by toxic heavy metals and potentially toxic chemicals due to their properties of inhabitation

Izmit Bay (Figure 1) is a semi-enclosed water body and situated in the NE of Marmara Sea. It has been subjected to pollution problems (Orhon et al., 1984; Tuğrul et al., 1989; Morkoç et al., 1996), including eutrophication of the water and inputs of toxic industrial and domestic effluents. Total organic matter load of industrial discharges has been reduced to 80% within the last 10 years, whereas domestic organic loads have been increased in two fold (Morkoç et al., 1996, 2001). The earthquake with a magnitude of 7.4 was occurred at 17th of August 1999, destroying the eastern Marmara Region. The epicenter of the earthquake was found to

**1. Introduction** 

(Pempcowiac et al., 1999; Hu 2000).

**Enrichment in the Lower Layer** 

**Water of Izmit Bay, Turkey** 

