**4. Geophysical campaign**

### **4.1. P-wave refraction**

A total of 10 seismic profiles are conducted at El Sakakini palace area (Figure 8). All profiles are carried out using 12 receivers, P-type geophones with 5m intervals and 2 shots. The forward and reverse shots were carried at a distance of 1 m at both ends. The seismic shots layouts are described in Table 1.

**Figure 8.** Location of the P-wave seismic refraction, S-wave refraction and ReMiprofiles conducted at ElSakakini Palace.


**Table 1.** Seismic shots.

Figure 7b. Geotechnical Borehole\_4, El Sakakini Palace.

**Figure 7.** a. Geotechnical Borehole\_1, El Sakakini Palace. b. Geotechnical Borehole\_4, El Sakakini Palace.

project : existing . habib pasha elsakakeeny palace

12 Engineering Seismology, Geotechnical and Structural Earthquake Engineering

classification

clayey silt . traces of mica .dark

fill( silty clay .medum u of pottery fragments .calc dark browen )

clayer silty sand . fine . traces of

dark brown silt clay with traces of fine sand

fine brown silt and sand with traces of

end of drilling at 15.00m

brown

rubble

clay &

fill( limestone fragments concrete frag.sand&silt calc dark brown fill( silty clay .tr of limestone &red brick &pottery fragments .calc dark browen )

file no : sakakeeny feb10 date commenced : May . 15- 2012 datecompleted : May . 18- 2012 weather : cold ground level : initial / final gwd : 1.10 m

end of layer (m)

7.40

2.75 2.00 2.25

2.00 2.20

31

12.10

14.00

15.00

qu (kg/ cm2)

spt n/30 cm

yb ( um3)

f.s. ( %)

wL ( %)

51 75 23 95

35 76 18 09

wP ( %)

RECOVERY ( %)

R.Q.D. ( %)

DRILL METHOD : MANUAL DRILLING

driller : alaa amin drilling co

drill fluid :none

Boring. no : 4 location :eldaher-cairo

legend

depth ( m)

**Formatted Table**

possible to distinguish the following three main layers: the soil layering can be summarized

Seismic Hazard Analysis for Archaeological Structures — A Case Study for EL Sakakini Palace Cairo, Egypt

**Soil A- Fill (<300 m/s):** A surface highly heterogeneous material (mainly man-made fill) with an average thickness of 10 m and an average velocity Vs lower than 300m/s. It is composed of very loose and low strength sediments such as silt, clay and limestone fragments. It is not found

**Soil B-Clayey soil (400-600 m/s):** Below the surface layer (soil A) there is a clayey or silty clay

**Soil C-Saturated Sand & Gravel (700-1300 m/s):** Below soil B there is a stiff soil layer with various thicknesses. it shows a considerable increase of Vs seismic velocity reaching sometimes values as high as 1300m/s. The soil is composed of compacted stiff saturated sand and gravel with an average Vs velocity equal or higher than 700m/s. It may be considered as the "seismic

**Layer A Layer B Layer C**

**(m)**

http://dx.doi.org/10.5772/54395

15

**Profile N° Velocity in m/s Velocity in m/s Depth (m) Velocity in m/s Depth in**

We have used the ReMi (refraction microtremors) method to determine the S-wave seismic velocity with depth. The method is based on two fundamental ideas. The first is that common seismic-refraction recording equipment, set out in a way almost identical to shallow P-wave refraction surveys, can effectively record surface waves at frequencies as low as 2 Hz (even lower if low frequency phones are used). The second idea is that a simple, two-dimensional slowness-frequency (P-f) transform of a microtremors record can separate Rayleigh waves from other seismic arrivals, and allow recognition of true phase velocity against apparent velocities. Two essential factors that allow exploration equipment to record surface-wave velocity dispersion, with a minimum of field effort, are the use of a single geophone sensor at each channel, rather than a geophone "group array", and the use of a linear spread of 12 or more geophone sensor channels. Single geophones are the most commonly available type, and are typically used for refraction rather than reflection surveying. There are certain advantages of ReMi method: it requires only standard refraction equipment, widely available, there is no need for a triggering source of energy and it works well in a seismically noisy urban setting.

 300 10 1300 25 600 16 900 32 400 9 700 20 400 14 1200 30 < 300 300 5 500 10

**Table 2.** P-wave refraction geophysical campaign conducted at El-Sakakini palace area.

layer with an average thickness of 10 m meters and Vs velocity 400-600 m/s.

bedrock" for the local site amplification analyses.

**4.2. Refraction- microtremor (ReMi method)**

(Louie, 2001, Pullammanappallil et al. 2003).

in the following (table 2).

in all locations.

geoseismic model for profiles # P1-P5 (Figure 8). **Figure 9.** P-wave travel time distance curve and its corresponding geoseismic model for profiles # P1-P5 (Figure 8).

Figure 9: P-wave travel time distance curve and its corresponding

The conducted profiles are interpreted using time-term inversion method; an example of the conducted profiles and corresponding geoseismic model is shown in Figure 9. Table 2 summarizes the measured Vs values and the corresponding soil thicknesses. The soil stratifi‐ cation is not uniform and horizontal, as it should be expected for a filled area. However it is possible to distinguish the following three main layers: the soil layering can be summarized in the following (table 2).

**Soil A- Fill (<300 m/s):** A surface highly heterogeneous material (mainly man-made fill) with an average thickness of 10 m and an average velocity Vs lower than 300m/s. It is composed of very loose and low strength sediments such as silt, clay and limestone fragments. It is not found in all locations.

**Soil B-Clayey soil (400-600 m/s):** Below the surface layer (soil A) there is a clayey or silty clay layer with an average thickness of 10 m meters and Vs velocity 400-600 m/s.

**Soil C-Saturated Sand & Gravel (700-1300 m/s):** Below soil B there is a stiff soil layer with various thicknesses. it shows a considerable increase of Vs seismic velocity reaching sometimes values as high as 1300m/s. The soil is composed of compacted stiff saturated sand and gravel with an average Vs velocity equal or higher than 700m/s. It may be considered as the "seismic bedrock" for the local site amplification analyses.


**Table 2.** P-wave refraction geophysical campaign conducted at El-Sakakini palace area.

### **4.2. Refraction- microtremor (ReMi method)**

Figure 9: P-wave travel time distance curve and its corresponding

**Clayey Layer 300-600 m/s**

**Figure 9.** P-wave travel time distance curve and its corresponding geoseismic model for profiles # P1-P5 (Figure 8).

The conducted profiles are interpreted using time-term inversion method; an example of the conducted profiles and corresponding geoseismic model is shown in Figure 9. Table 2 summarizes the measured Vs values and the corresponding soil thicknesses. The soil stratifi‐ cation is not uniform and horizontal, as it should be expected for a filled area. However it is

**Saturated Sand & Gravel 700-1300 m/s**

P1 P2

**Formatted Table**

P3 P4

P5

geoseismic model for profiles # P1-P5 (Figure 8).

**Fill Layer 300 m/s**

14 Engineering Seismology, Geotechnical and Structural Earthquake Engineering

We have used the ReMi (refraction microtremors) method to determine the S-wave seismic velocity with depth. The method is based on two fundamental ideas. The first is that common seismic-refraction recording equipment, set out in a way almost identical to shallow P-wave refraction surveys, can effectively record surface waves at frequencies as low as 2 Hz (even lower if low frequency phones are used). The second idea is that a simple, two-dimensional slowness-frequency (P-f) transform of a microtremors record can separate Rayleigh waves from other seismic arrivals, and allow recognition of true phase velocity against apparent velocities. Two essential factors that allow exploration equipment to record surface-wave velocity dispersion, with a minimum of field effort, are the use of a single geophone sensor at each channel, rather than a geophone "group array", and the use of a linear spread of 12 or more geophone sensor channels. Single geophones are the most commonly available type, and are typically used for refraction rather than reflection surveying. There are certain advantages of ReMi method: it requires only standard refraction equipment, widely available, there is no need for a triggering source of energy and it works well in a seismically noisy urban setting. (Louie, 2001, Pullammanappallil et al. 2003).

A 12 channel ES-3000 seismograph was used to measure background 'noise' enhanced at quiet sites by inducing background noise with 14Hz geophones in a straight line spacing 5m Figure 5 shows the map were ReMi measurements were made. Almost all the sites were noisy. In particular big hammer used to break some rocks generated noisy background at El Sakakini Palace.30 files of 30sec records (unfiltered) of 'noise' were collected at each site. Five profiles were taken inside the Palace (Figure 8). Figure 10-11 shows an example of the dispersion curves and its P-F image (Remi Spectral ratio of surface waves) for refraction microtremors profile ReMi-1. The estimated average Vs for all profiles are shown in Figure 12.

Figure 12. Shear wave velocity model calculated for refraction microtremors profiles ReMi-1

Seismic Hazard Analysis for Archaeological Structures — A Case Study for EL Sakakini Palace Cairo, Egypt

http://dx.doi.org/10.5772/54395

17

**Figure 12.** Shear wave velocity model calculated for refraction microtremors profiles ReMi-1 To ReMi-5 (Figure 9).

**5-FREQUENCY CHARACTERSITICS OF THE SOIL AND THE** 

**5. Frequency charactersitics of the soil and the building using microtremrs**

Microtremors are omnipresent low amplitude oscillations (1-10 microns) that arise predomi‐ nantly from oceanic, atmospheric, and urban or anthropogenic actions and disturbances. The implicit assumption of early studies was that microtremors spectra are flat and broadband before they enter the region of interest (soil or building). When microtremors enter preferable body it changes and resonate depending on the nature of the material, shape, and any other

Microtremors are omnipresent low amplitude oscillations (1-10 microns) that arise predominantly from oceanic, atmospheric, and urban or anthropogenic actions and disturbances. The implicit assumption of early studies was that microtremors spectra are flat and broadband before they enter the region of interest (soil or building). When microtremors enter preferable body it changes and resonate depending on the nature of the material, shape,

It may be considered to compose of any of seismic wave types. We have two main types of microtremors, Local ambient noise coming from urban actions and disturbances and long period microtremors originated from distances (e.g. oceanic disturbances). There is still a debateongoing on the characteristics of the ambient noise that should be used for site characterization and ground response. While some are using only the longer period microtremors originated from farther distances (e.g. Field et al, 1990), others considered that traffic and other urban noise sources are producing equally reliable results. In general low amplitude noise measurements comparable results give with strong motion data (Raptakis et al, 2005 ., Pitilakis, 2011., Apostolidis et al., 2004., Manakou et al, 2010., Mucciarelli, 1998). Kanai 1957, first introduced the use of microtremors, or ambient seismic noise, to estimate the earthquake site response (soil amplification). After that lots of people followed this work but from the point of soil amplification of earthquake energy for different frequencies (e.g. Kanai and Tanaka 1961 and Kanai 1962, Kagami et al, 1982 and 1986; Rogers et al., 1984;

2011., Apostolidis et al., 2004., Manakou et al, 2010., Mucciarelli, 1998).

It may be considered to compose of any of seismic wave types. We have two main types of microtremors, Local ambient noise coming from urban actions and disturbances and long period microtremors originated from distances (e.g. oceanic disturbances). There is still a debateongoing on the characteristics of the ambient noise that should be used for site charac‐ terization and ground response. While some are using only the longer period microtremors originated from farther distances (e.g. Field et al, 1990), others considered that traffic and other urban noise sources are producing equally reliable results. In general low amplitude noise measurements comparable results give with strong motion data (Raptakis et al, 2005., Pitilakis,

Kanai 1957, first introduced the use of microtremors, or ambient seismic noise, to estimate the earthquake site response (soil amplification). After that lots of people followed this work but from the point of soil amplification of earthquake energy for different frequencies (e.g. Kanai and Tanaka 1961 and Kanai 1962, Kagami et al, 1982 and 1986; Rogers et al., 1984; Lermo et al.,

To ReMi-5 (Figure 9).

characteristics of this body.

**BUILDING USING MICROTREMRS** 

and any other characteristics of this body.

Lermo et al., 1988; Celebi et al. 1987).

1988; Celebi et al. 1987).

**Figure 10.** Dispersion curve showing picks and fit for Profile ReMi-1

**Figure 11.** P-F image with dispersion modeling picks for Profile ReMi-1

Seismic Hazard Analysis for Archaeological Structures — A Case Study for EL Sakakini Palace Cairo, Egypt http://dx.doi.org/10.5772/54395 17

A 12 channel ES-3000 seismograph was used to measure background 'noise' enhanced at quiet sites by inducing background noise with 14Hz geophones in a straight line spacing 5m Figure 5 shows the map were ReMi measurements were made. Almost all the sites were noisy. In particular big hammer used to break some rocks generated noisy background at El Sakakini Palace.30 files of 30sec records (unfiltered) of 'noise' were collected at each site. Five profiles were taken inside the Palace (Figure 8). Figure 10-11 shows an example of the dispersion curves and its P-F image (Remi Spectral ratio of surface waves) for refraction microtremors profile

ReMi-1. The estimated average Vs for all profiles are shown in Figure 12.

16 Engineering Seismology, Geotechnical and Structural Earthquake Engineering

**Figure 10.** Dispersion curve showing picks and fit for Profile ReMi-1

**Figure 11.** P-F image with dispersion modeling picks for Profile ReMi-1

Figure 12. Shear wave velocity model calculated for refraction microtremors profiles ReMi-1 **Figure 12.** Shear wave velocity model calculated for refraction microtremors profiles ReMi-1 To ReMi-5 (Figure 9).

To ReMi-5 (Figure 9).

#### **5-FREQUENCY CHARACTERSITICS OF THE SOIL AND THE 5. Frequency charactersitics of the soil and the building using microtremrs**

**BUILDING USING MICROTREMRS**  Microtremors are omnipresent low amplitude oscillations (1-10 microns) that arise predominantly from oceanic, atmospheric, and urban or anthropogenic actions and disturbances. The implicit assumption of early studies was that microtremors spectra are flat and broadband before they enter the region of interest (soil or building). When microtremors enter preferable body it changes and resonate depending on the nature of the material, shape, and any other characteristics of this body. Microtremors are omnipresent low amplitude oscillations (1-10 microns) that arise predomi‐ nantly from oceanic, atmospheric, and urban or anthropogenic actions and disturbances. The implicit assumption of early studies was that microtremors spectra are flat and broadband before they enter the region of interest (soil or building). When microtremors enter preferable body it changes and resonate depending on the nature of the material, shape, and any other characteristics of this body.

It may be considered to compose of any of seismic wave types. We have two main types of microtremors, Local ambient noise coming from urban actions and disturbances and long period microtremors originated from distances (e.g. oceanic disturbances). There is still a debateongoing on the characteristics of the ambient noise that should be used for site characterization and ground response. While some are using only the longer period microtremors originated from farther distances (e.g. Field et al, 1990), others considered that traffic and other urban noise sources are producing equally reliable results. In general low amplitude noise measurements comparable results give with strong motion data (Raptakis et al, 2005 ., Pitilakis, 2011., Apostolidis et al., 2004., Manakou et al, 2010., Mucciarelli, 1998). Kanai 1957, first introduced the use of microtremors, or ambient seismic noise, to estimate It may be considered to compose of any of seismic wave types. We have two main types of microtremors, Local ambient noise coming from urban actions and disturbances and long period microtremors originated from distances (e.g. oceanic disturbances). There is still a debateongoing on the characteristics of the ambient noise that should be used for site charac‐ terization and ground response. While some are using only the longer period microtremors originated from farther distances (e.g. Field et al, 1990), others considered that traffic and other urban noise sources are producing equally reliable results. In general low amplitude noise measurements comparable results give with strong motion data (Raptakis et al, 2005., Pitilakis, 2011., Apostolidis et al., 2004., Manakou et al, 2010., Mucciarelli, 1998).

the earthquake site response (soil amplification). After that lots of people followed this work but from the point of soil amplification of earthquake energy for different frequencies (e.g. Kanai and Tanaka 1961 and Kanai 1962, Kagami et al, 1982 and 1986; Rogers et al., 1984; Lermo et al., 1988; Celebi et al. 1987). Kanai 1957, first introduced the use of microtremors, or ambient seismic noise, to estimate the earthquake site response (soil amplification). After that lots of people followed this work but from the point of soil amplification of earthquake energy for different frequencies (e.g. Kanai and Tanaka 1961 and Kanai 1962, Kagami et al, 1982 and 1986; Rogers et al., 1984; Lermo et al., 1988; Celebi et al. 1987).

#### **5.1. Instrumentation and data acquisition**

A high dynamic range Seismograph (Geometrics ES-3000 see Figure 13) mobile station with triaxial force balance accelerometer (3 channels), orthogonally oriented was used. The station was used with 4Hz sensors to record the horizontal components in longitudinal and transverse directions in addition to the vertical components. For the data acquisition and processing we followed the following steps:

**•** Smoothing the final response curves by running average filter for better viewing. A complete

Seismic Hazard Analysis for Archaeological Structures — A Case Study for EL Sakakini Palace Cairo, Egypt

Figure 14 shows the locations of microtremors stations used to determine the ground response at EL Sakakini Palace area. The predominant frequency of the ground at EL Sakakini Palace is about 3 Hz (see Figure 15 & Table 1), a value almost identical to the theoretical estimation according to Kennett and Kerry (1979) (Figure 16 & Table 4). The amplification factor is about

**S2 S1**

**S4**

**Soil Response stations**

http://dx.doi.org/10.5772/54395

19

**S3**

**S5**

description of the methodology can be found in Gamal and Ghoneim, (2004).

**5.2. Ground response**

2, which is relatively low.

**Figure 14.** Ambient noise measurement locations


**Figure 13.** High dynamic range ES-3000 Geometrics mobile station and triaxial geophone used 4 Hz to drive soil re‐ sponse of El-Sakakini Palace.

Each of these series was tapered with a 3-sec hanning taper and converted to the frequency domain using a Fast Fourier transform,


**•** Smoothing the final response curves by running average filter for better viewing. A complete description of the methodology can be found in Gamal and Ghoneim, (2004).
