الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Faults represent the primary mechanical discontinuities of the elastic–
brittle Earth’s upper crust. Active faults are considered the reason for many
earthquakes and tend to occur near tectonic plate boundaries. Earthquakes are
one of the natural disasters that not only disturbed the life pattern, but also
cause massive losses of life, property and interrupted the process of
development. Therefore, earthquakes disaster prevention and reduction
strategy are a global concern today.
Seismic wave propagation in the upper layers of the earth’s crust
controls the spread of the earthquake disaster in an area (Aggarwal et al.,
2003). The aim of seismic response analysis is to determine the effect of
seismic waves on a particular site, as a seismic hazard or risk depends on the
seismic source, the function of transfer media, local geology, type of
structures and soil structure interaction (Okamoto et al. 1973).
The main objectives of the present work are the mitigation of
earthquake damages and anticipate the future healthy development of the
buildings and structures in the Suez Canal area through the following main
points:
- Analysis of digital data with modern methods to determine the source
mechanism of the moderate magnitude earthquakes that have been
recorded recently by the Egyptian National Seismological Network
(ENSN) depending on the polarity of the first motion of P-wave and
amplitude ratios during the period from 2009 to 2015.
- Estimation of fundamental frequencies and H/V amplitudes for
different sites at Suez, Ismailia, and Port Said cities in the study area.
Estimation of Shear-wave velocity profiles at shallow depths using
Multichannel Analysis of Surface Waves (MASW) method.
- Determination of shear-wave velocity structure at much deeper layers
using the array seismic technique.
- Estimation of strong ground motion parameters such as peak ground
acceleration at several sites depending on local site effect on the study
area.
The study area extends from latitudes 29˚90’N to 31˚30’N and
longitudes 32˚00’E to 33˚80’E. This thesis consists of four chapters
Chapter I presents an introduction, datasets, methodology, and the
geologic and tectonic setting of the study interest area. They are summarized
as she study area comprises three main cities: Suez, Ismail, and Port Said and
includes a variety of anthropogenic activities such as power plants, tunnels,
irrigation canal, industrial centers, agricultural lands and pipelines as well as
new urbanization.
The Suez Canal is the most commercially utilized and the longest
excavated waterway in the world. The Suez Canal provides savings on
distance, time of sailing and costs of transportation. The area around the Suez
Canal selected for the current study due to the strategic importance and the
significant investments that are carrying out at the present time and future.
The Study area is affected by small to moderate earthquake activity.
The most damaged earthquakes experienced surrounding area of Suez Canal
are:- Shadwan earthquake in 1969 with magnitude Mw=6.9 (Maamoun and
El-Khashab, 1978), Gulf of Aqaba earthquake on 22 November 1995 with
Mw= 7.3 (Marzouk, et al., 1996), the very close two events occurred on 18
and 22 of July 2014 near Suez City, with local magnitude (ML=4.0) and
(ML=4.3) (NRIAG, 2014) respectively, as well as Gulf of Aqaba earthquake
in 2015 (ML=5.2) (NRIAG, 2015), Hagul earthquake (ML=3.8) in 2007
Summary and Conclusions
136
(Abou El-enean et al., 2010), and earthquakes of Mediterranean offshore
(e.g., Alexandria earthquake in 1955, Ms=6.8 (Rothe, 1969) and Cyprus
earthquake in 1996, Mw=6.8 (Abou El-enean, 2007).
Data sets are collected by the following:
from recent moderate magnitude earthquakes that have recorded by the
Egyptian National Seismological Network (ENSN).
Single seismic station ambient noise recordings (Microtremor).
Surface wave recordings by an active source.
Ambient noise recorded by an array of sensors (passive source).
Strong ground motion data (history and recent of significant moderate
to large magnitude earthquakes that have been occurring in and
surrounding the Suez Canal area).
The methods and software’s were used in the present work are:
1. SEISAN Software is a seismic analysis system that helps to analyze
earthquakes. This software used for determining the epicenter of the
earthquakes and focal mechanism.
2. Horizontal-to-Vertical (HVSR) spectral ratio (Nakamura technique)
used for the identification of the fundamental frequency (fo) of the
soil and corresponding H/V peak amplitude (Ao) ratios.
3. MASW technique used for used to obtain the shear-wave velocity
(Vs) profile at different sites.
4. Frequency-wavenumber (F-K) method was applied successfully to
drive the dispersion curves of surface waves from ambient vibrations
derived to form Array technique.
5. SMSIM-Fortran Program used for simulation of ground motion for a
particular site.
from the geologic setting of the study area, the Suez Canal area and its
surroundings occupy a semi-flat terrain with ripple marks trending from the
north to the south. The study area includes features of sabkha deposits. It is
controlled by the content and distribution of water-soluble salts through
parent rocks (Moustafa, and Khalil, 1995). The Suez Canal area includes
three provinces as follow: -
1) The southern province includes the Suez City and Bitter Lakes area
which represents a part of the transitional zone between the Gulf of Suez rift
and the unstable shelf of the northern part of Egypt (Omaran, 1989 and
Geriesh, 1989). This province covered by sedimentary rocks belonging from
the Cretaceous to Pleistocene-Holocene ages, (Figure 1.2). The Late and
Early Cretaceous and The Middle Eocene sediments have exposed at Gebel
Shabraweet.
2) The central province includes Ismailia City and El-Temsah Lake
along the coast of the Canal; it is located approximately half-way between
Port Said and Suez. It consists of five towns; Ismailia, Fayed, Al-Tal Al-
Kabeer, Qantara west and east. El-Temsah Lake formed in a depression
situated in a fault trough (Holmes, 1965 and El Shazley et al., 1974).
3) The Northern Province extended from Qantara, El-Cap, The El-
Tina Plain, Ras El-Ish and ended by Port Said city. It is located on the
Mediterranean Sea coast to the north. The western boundary encompasses a
portion of the eastern shore of the Manzala Lake to a point roughly 5 Km
south of El-Cap and runs east of the Suez Canal and 8 km into Sinai.
from tectonic setting, the Suez Canal area lies to the northwest of the
still active Gulf of Suez Rift system. It represents a part of the transitional
zone between the Gulf of Suez taphro-geosyncline and the unstable shelf of
the northern part of Egypt (Said, 1962 and Smith, 1984). The Bitter Lakes is
situated in a fault trough; this fault extends for more than 150 km in Sinai and
trends NNW-SSE across the Suez Canal according to (El-Shazly et al., 1975).
Some E-W oriented normal faults that divided the Suez Canal from
south to north into the Bitter Lakes graben and Ismailia horst. Like the E-W
oriented faults affecting Cairo-Suez zone, they were mostly originally formed
in Late Triassic-Early Jurassic during the rifting of the African-Arabian plate
away from the Eurasian plate.
The subsurface geological and geophysical studies show that the soils
in the southern province of the studied area are composed of Miocene sandy
marl overlies limestone. The thickness of soft sediments reached to 15 m
depth. While in the central part, the subsurface soils composed of Quaternary
alluvial of two distinct sedimentary units of clay and sand that overlie
Miocene sandy marl. So, the thickness of soft sediments increased and up to
30 m depth (Mohamed and Hamdy, 2012).
Chapter II demonstrates the seismicity of the study area during the
period from 2009 to 2014 These data are recorded by the National Seismic
Network (ENSN). The earthquakes are distributed along specific seismic
zones as the aims of the present chapter are:
The determination of source mechanism of moderate size earthquakes
using polarities of the first motion of P-waves and amplitude ratios of P, SH,
and SV-waves. The Suez Canal area is characterized by small seismic
activity. However, the surrounding areas have moderate seismic activity due
to the interactions between African, Arabian, and Eurasian plates and the
Sinai subplate. The data used in this study are selected from well-recorded
events (ML ≥ 3) in and around the Suez Canal during the period from 2009 to
2014.
The focal mechanism solutions in the study area and its surrounding
zones demonstrate mainly a normal faulting, pure extensional, with strike-slip
components, some focal mechanisms reflect strike-slip faults and few reflect
reverse faults. Our results indicate that Suez Canal and its surrounding areas
are dominated by three groups of neotectonic regimes. These are extensional
tectonic regime, normal to strike-slip regime, strike-slip tectonic regime, and
reverse tectonic regime.
The focal mechanisms are coinciding with the major tectonic trends
along the northern Red Sea, the Suez rift, Aqaba rift with their connection
with the great rift system of the Red Sea and Cairo-Suez shear zone. As well
as, Nile Delta Cone that is located on the passive continental margin is
characterized by a compressional stress. Therefore, the focal mechanism is
this area demonstrated reverse faulting mechanism. Moreover, it is
compatible with the fault plane solutions of most of the past earthquakes that
shown in (Figure 2.11) (Korrat et al., 2005).
Chapter III presents local site effect around the Suez Canal; the Site
effects play a significant role in characterizing ground motions because they
may amplify ground motion within the uppermost layer of the ground (Abd
El-Aal, 2010 due to the impedance contrast between sediments and the
underlying bedrocks. The identification of the fundamental frequency of soil
deposits is gaining increasing importance for seismic site effect assessment
because it carries implicit information about the bedrock depth and shear
wave velocity of the soils, which is related to soil shear stiffness. In the
present study, different methods were applied: The H/V method (Nakamura
technique), Multichannel analysis of surface waves (MASW technique) and
Array technique.
Summary and Conclusions
140
HVSR technique, known as Nakamura’s technique (Nakamura, 1989)
used for determining HVSR peak frequencies and HVSR peak amplitude
values based on a recording of the ambient noise by using the GEOPSY
software. Multichannel Analysis of Surface Waves (MASW) method is a
seismic exploration method used to estimate the shear wave velocity profile
of near-surface materials. Recordings of noise array processed using the F-K
method (Lacoss et al. 1969) on vertical components only. (F-K) method was
applied successfully to drive the dispersion curves of surface waves from
ambient vibrations.
The ambient noise measurements were carried out at 61 sites along
Suez Canal area in three cities: Suez, Ismailia, and Port-Said using a single
station consists of high sensitivity seismometer (Trillium 120 compact). The
measurements of surface waves (Rayleigh waves) carried out at seven sites in
the Suez Canal area. Also, seven arrays implemented in the study area.
The shear wave velocity increasing to the south along the Suez Canal
due to cementation, and overburden pressure, while it is decreasing to the
north due to soft sediments of Sabkha deposits and soft soil on shallow
bedrocks that occupied in this area. The results obtained from array technique
demonstrate that the shear wave velocity (Vs) decreases to the north along
the Suez Canal. These results are compatible with H/V values.
The main objectives of Chapter III are;
- The estimation of the effect of local geology on the seismic motion
in terms of fundamental resonance frequency (fo) and its associated
H/V amplitude (Ao) for determining the seismic hazard to a given
site.
- Investigate the shear wave velocity and site classification by
applying the MASW technique at different locations in the study
area.
- For the derivation of the S-wave velocities as they need for the
assessment of local site effects in seismic hazard studies, depending
on ambient vibration array measurements by the frequencywavenumber
(F-K) method
The results of this study indicated that the southern part of the area has
low values of the H/V amplitudes and high values of P- and S-wave
velocities, Vp= 2000 m/s and Vs=547.7 m/s. On the other hand, the northern
part of the study area is characterized by high values of the H/V amplitude
and low values of P and S-waves, Vp= 1435 m/s and Vs= 109.8 (that is due to
thick sediments which are friable and loose), which leads to the high
impedance contrast between the uppermost surface soil and the underlying
bedrocks.
Chapter IV demonstrates the simulation of ground motion; strong
ground motions induced by earthquakes have variable amplitudes, durations
and frequency contents. Design and evaluation of structures and
infrastructures under seismic hazard require the knowledge of ground motion
records if time history analysis is considered. However, the available
historical records are limited and may not match the desired and identified
scenario events; so, synthetic records may be considered.
A ground motion prediction equation (GMPE) is a generic term for an
equation providing a statistical estimate of the expected ground motion and
its standard deviation due to a given earthquake scenario. The measure of
ground-motion provided by a GMPE is typically 5% damped relative pseudospectral
acceleration (PSA). The ground motion amplification and high level
of damages over soft soil and unconsolidated deposits have been shown to be
responsible for increasing seismic intensity over than the consolidated and
hard sediments.
The simulation of the ground motion at a certain site requires detection
of seismic sources of hazardous effects, a controlling earthquake, the
attenuation model, and the site amplification effect. The simulations will
apply to the random horizontal component of the shear wave of ground
motion. The stochastic point-source method is used with the specification of
the Fourier amplitude spectrum of ground acceleration as a function of
seismic moment and distance.
In this study, the digital data include historical analysis and recent
records of moderate and large earthquakes that recorded in and around the
Suez Canal during the period from 1997 to 2015 and microtremor
measurements were used for the simulation of ground motion in the study
area.
The PGA is estimated for Abu-Hammad earthquake, Ismailia
earthquake, Suez earthquakes, Gulf of Aqaba, Dahshur, and Nile Delta Cone
seismic sources and are listed in Table (4.1). The peak ground acceleration
was calculated for different sites at Suez, Ismailia, and Port Said cities by
using the stochastic simulation method on seismic sources that are listed in
Table (4.1). The highest value was found to be 285 gals at Ismailia city with
amplification factor 4. While the lowest value was found to be 0.1 gal at Port
said from seismic source 9 (Gulf of Aqaba) due to the distance up to 350 km.
The response spectrum (0.5%, 1%, 5%, 10% and 20% damped pseudoacceleration)
for frequencies of 0.5 to 1.08 Hz was simulated for nine
earthquakes and are listed in Table (4.1) for the 19 sites (low and high
amplification sites) at Suez, Ismailia, and Port Said cities (Figures. 4.5, 4.6,
4.7, 4.8, 4.9, 4.10, 4.11, and 4.12). The peak ground acceleration at the
studied areas indicates that Ismailia earthquake occurred on 02/01/1987
affected the investigated sites than the other earthquakes.
In general, the peak ground acceleration values are depending on
amplification factors, distance from the source to the site, and magnitude
size. Therefore, the high acceleration values are characterized by strong
ground motion amplification factors as illustrated in Figure (4.12).
The resulting suite of GMPE can be estimated by using all possible
equivalent rupture distances represents the probability distribution of groundmotion
estimates for the given scenario. The response spectrum, which
reflects the characteristics of the earthquake and the nature of the recording
site, was calculated at different locations and various damping values.
Finally, the hazard reduction from earthquake disasters becomes a primary
concern in Egypt, which is moving rapidly towards huge investments in the
field of development, especially the Suez Canal area. This present work
presents valuable results, which are useful for civil engineers to develop
building code for the western side of the Suez Canal area