Preface

This book presents different aspects of earthquake research. In includes syntheses of recent works combined with new results and interpretations, applicable to diverse branches of earthquake seismology and geology.

The destructive potential of earthquakes depends on their magnitude and the placement of the hypocenter. Worldwide efforts, such as the Global Seismographic Network of seismological and geophysical sensors and data centers, provides information that is essential to identify earthquake locations, understand the physics of the earthquakes and faulting mechanisms, as well as studies on paleoseismicity and earthquakes in the human history. These types of studies play a key role in mitigating earthquake hazards and planning emergency response. Geological studies on tectonic landforms and advances in the theoretical and applied physics of seismology have led to the creation of numerical models for seismic activity, improvement of design methods and testing practices for earthquake-resistant construction and seismic retrofit, as well as observation and monitoring. The study of earthquakes combines science, technology and expertise in infrastructure and engineering in an effort to minimize human and material losses when their occurrence is inevitable.

The chapters in this book are devoted to various aspects of earthquake research and analysis, such as seismology, seismotectonic and earthquake geology.

The first chapter presents a study on ways to find out about the seismic past of a region. This is really important because identification and reliable description of past earthquakes is of great importance for the seismic assessment in a particular area and it represents a reliable projection of future earthquakes. Even though the paper focuses on, but is not limited to, German attempts, it offers a clear picture of historical earthquakes and their reception history, ancient and early modern attempts to collect earthquake information, early earthquake catalogue compilation and open source ways to collect earthquake information.

Chapters 2 and 3 discuss the trace of earthquakes through some examples of seismites from Turkey and through studies on paleoearthquakes in Central Asia. The authors describe sedimentary beds disturbed by seismic shaking known as seismites. The main goal of chapter 2 is to determine the different deformation structures in Lake Van

#### XII Preface

deposits, interpret the triggering mechanism and discuss the importance of these structures in regional tectonic. Chapter 3 focuses on strong paleoearthquakes along the Talas-Fergana Fault to improve the understanding of the intracontinental deformation of the Tien Shan mountain belt as a whole, and the occurrence of strong earthquakes along the largest wrench structure in Central Asia.

Chapter 4 presents some study on paleoseismic investigation. The authors analyzed the paleoseismic evidence for earthquake rupture at four excavated sites along the fault responsible for the destructive earthquake in Taiwan in 1999 (Mw=7.6). They suggest that "the evolutionary path of thrust-related folds develops from faultpropagation folding to breakthrough fault-propagation folding, and finally to faultbend folding".

Chapter 5 deals with the generation mechanism of giant earthquakes in subduction zones. The authors discuss a numerical simulation approach in order to set up a model in subduciton zones. They were able to quantitatively explain the features of the 2011 M9 earthquake in Japan using a hierarchical asperity model.

Chapter 6 also deals with earthquakes in subduction zones by investigating the process and mechanisms of slow-earthquake migration. The chapter presents a comparison of results obtained by observation and numerical simulations. Furthermore, the authors discuss a new method for detecting changes around important asperities before megathrust earthquake.

Chapter 7 is an example of a seismology paper and deals with the determination of focal depth of small and moderate earthquakes using teleseismic depth phases, which is crucial information for many studies in seismology. The chapter shows several examples and comparisons among the focal depth obtained using teleseismic phase as well as other results obtained using other methods, and the consistency in the comparisons is good.

Chapter 8 investigates the crustal structure of the Azorean plateau region, describing the results obtained by using 1-D and 3-D inversions. It illustrates the use of several techniques well-known in earthquake seismology and shows the results of intense seismic and volcanic activity.

Chapter 9 deals with identifications of structure in non-tectonic areas inferred using seismogram analysis of earthquakes recorded in Taiwan.

Chapter 10 presents results on the tectonic background of the Wenchuan earthquake area. Due to the complicated tectonic environment of northwestern Sichuan, several different results are presented. The paper sheds light on the tectonic process of the area and tries to clarify several hypotheses.

Chapter 11 reports statistical studies applied to seismology. In particular, two different approaches are used to investigate non-linear analysis. Fractal approach to characterize the time-clustering phenomenon is also investigated. The goal of the paper is to propose a general methodology to obtain better estimates of the earthquake hazard.

X Preface

bend folding".

comparisons is good.

seismic and volcanic activity.

deposits, interpret the triggering mechanism and discuss the importance of these structures in regional tectonic. Chapter 3 focuses on strong paleoearthquakes along the Talas-Fergana Fault to improve the understanding of the intracontinental deformation of the Tien Shan mountain belt as a whole, and the occurrence of strong earthquakes

Chapter 4 presents some study on paleoseismic investigation. The authors analyzed the paleoseismic evidence for earthquake rupture at four excavated sites along the fault responsible for the destructive earthquake in Taiwan in 1999 (Mw=7.6). They suggest that "the evolutionary path of thrust-related folds develops from faultpropagation folding to breakthrough fault-propagation folding, and finally to fault-

Chapter 5 deals with the generation mechanism of giant earthquakes in subduction zones. The authors discuss a numerical simulation approach in order to set up a model in subduciton zones. They were able to quantitatively explain the features of the 2011

Chapter 6 also deals with earthquakes in subduction zones by investigating the process and mechanisms of slow-earthquake migration. The chapter presents a comparison of results obtained by observation and numerical simulations. Furthermore, the authors discuss a new method for detecting changes around

Chapter 7 is an example of a seismology paper and deals with the determination of focal depth of small and moderate earthquakes using teleseismic depth phases, which is crucial information for many studies in seismology. The chapter shows several examples and comparisons among the focal depth obtained using teleseismic phase as well as other results obtained using other methods, and the consistency in the

Chapter 8 investigates the crustal structure of the Azorean plateau region, describing the results obtained by using 1-D and 3-D inversions. It illustrates the use of several techniques well-known in earthquake seismology and shows the results of intense

Chapter 9 deals with identifications of structure in non-tectonic areas inferred using

Chapter 10 presents results on the tectonic background of the Wenchuan earthquake area. Due to the complicated tectonic environment of northwestern Sichuan, several different results are presented. The paper sheds light on the tectonic process of the

Chapter 11 reports statistical studies applied to seismology. In particular, two different approaches are used to investigate non-linear analysis. Fractal approach to characterize

along the largest wrench structure in Central Asia.

M9 earthquake in Japan using a hierarchical asperity model.

important asperities before megathrust earthquake.

seismogram analysis of earthquakes recorded in Taiwan.

area and tries to clarify several hypotheses.

Chapters 12 and 13 analyze complex signals associated with geoelectric activity and methods of electrical conductivity determination respectively, focusing on two different areas of the globe. In particular, chapter 12 reports some complexity studies of geoelectric signals during a two-year period, from June 1, 1994 to May 31, 1996, in two sites (Acapulco and Coyuca stations) located in southern Mexico. Chapter 13 focuses on the EM image beneath southwest Japan. A comparative study with the northeast Japan area is made.

Chapter 14 covers the hydrological changes associated with some of the big earthquakes that occurred in the Southern Apennines (Italy) during the XX century. The seismic events that occurred in 1930, 1980 and 1984 are investigated and the types of hydrological effects are also reported for each earthquake.

Chapter 15 presents the important issue of rock-fluid interactions along seismogenic faults. In this paper, the authors explain the interactions at the fault by analyzing clay minerals within the fossil seismogenic fault along the subduction interface.

Chapter 16 is a nice example of a mathematical approach to derive inequalities for comparing the change of pore pressure with that of frictional coefficient during fault slip.

Chapter 17 discusses the contribution of seismic frictional heat to the total earthquake energy budget. The author describes the ESR (electron spin resonance) technique and shows the scanning ESR microscopic technique for sequential high-resolution measurements for the detection of seismic frictional heat. The case of the Nojima fault rocks in Japan is presented in detail.

Chapter 18 describes a methodology for constraining the structural lineaments in active tectonic areas by integrating morphological and morphometrical data derived by DEMs (Digital Elevation Models) processing, with different geophysical data, as local seismicity and ground deformation data. Furthermore, validation of the lineaments extracted from DEM is carried out by looking over geological and geomorphological maps of literature, available aerial photo and field surveys reports. Three different case study areas are presented.

Chapter 19 presents a description of studying seismic signals associated to volcanic earthquakes. In particular, the pattern recognition (PR) technique is applied as a valid tool for the volcano-seismic monitoring. This chapter briefly introduces fundamental concepts regarding seismic volcanic signals and PR systems. Moreover, it raises the important issue of transferring prototype academic results into deployed technology.

We can conclude that the book collects different approaches which are really important to better understand such a complex phenomenon and which are also critical in terms of civil protection and associated risk assessment. This represents the ultimate goal since such seismic activity often has a significant impact in economic and human terms.

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Finally, I would like to express my special thanks to Mr. Igor Babic and Ms. Ivana Lorkovic. Last but not least, I would like to thank the whole staff of InTech Open Access Publishing, especially Mr. Igor Babic, for their professional assistance and technical support during the publishing process that has led to the realization of this book.

> **Sebastiano D'Amico**  Research Officer III Physics Department University of Malta Malta
