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Papers by Mostafa Toni

Areal-Source and Fault-Source Based Probabilistic Seismic Hazard Analysis Using Characteristic Earthquake Model and Monte-Carlo Approach: An Example of the Gulf of Aqaba Region

Seismicity and Seismotectonic of North Africa: An Updated Review

Regional geology reviews, 2024

Journal of Applied Geophysics (Cairo)

The Egyptian government is active in multiple areas designated for industry and urban development... more The Egyptian government is active in multiple areas designated for industry and urban development on the outskirts of both the capital and various governorates within newly established cities. The proposed site for the creation of the industrial zone of New-Cairo City is regarded one of Egypt's most promising commercial and combined services zones. The study's primary goal is to map the region's subsurface geological conditions and interpret the findings for geotechnical qualities of the underlying materials. The study aims to evaluate the properties of the subsurface layers to determine their suitability for construction and engineering purposes. The study is a case study that focuses specifically on the combined services area of Madinaty, to assess the suitability of the subsurface layers for geotechnical engineering purposes. To gather data about the subsurface layers, the investigation employed two geophysical techniques: Electrical Resistivity Tomography (ERT) and Shallow Seismic Refraction (SSR). SSR is used in the study area to identify dynamic geotechnical characteristics of the base layers using the P-wave and S-wave velocities. Two sub-surface layers are identified based on the velocity values of the Geo-seismic layers. The first layer is composed of mixed soil of sand, clay, and gravel, where the second layer composes of hard Limestone. According to all the criteria, regarding engineering aims, the area is divided into high, moderate, and low competent-material zones with varying degrees of fittingness. The current study suggested sorting the fundamental subsurface materials in the high and moderate zone for engineering purposes.

Indian Geotechnical Journal, 2017

A moderate earthquake (Ms = 5.8) was occurred on October 12, 1992 at about 25 km south west of Ca... more A moderate earthquake (Ms = 5.8) was occurred on October 12, 1992 at about 25 km south west of Cairo city-Egypt. It caused large damage to numerous poorly constructed buildings. One of the important seismological phenomenon happened during the earthquake is the soil liquefaction which was associated usually with the occurrence of big sand-boils near the epicenter of the earthquake. Recently different methods are used to reevaluate the liquefaction potentiality, in this study five different sites that showed high liquefaction potentiality during Cairo earthquake, have been selected to be studied to for re-evaluate liquefaction potentiality in Egypt. Shear wave velocity determination provides a promising tool to calculate the factor of safety (FS) against liquefaction, and resistance evaluation of sandy soils against this phenomenon. Multi-channel analysis of surface wave method as an efficient tool and is here used to infer the velocity profile at the considered sites to be used as input for the calculation of FS as an indication for liquefaction potentiality. The aim of this study is to determine the potentiality of liquefaction phenomenon in the selected sites to be one of soil characteristics input for any further hazard study. The selected five sites are named: Aquaz, Atf, Bedsa, El-Gammal, Zaweit Dahshour showed a liquefaction liquation during the 1992 Cairo earthquake which forced us to reevaluate and update our knowledge through the recent technique about the liquefaction potentiality at these sites. The FS obtained by using shear wave was compared with the values obtained from SPT from previous studies.

Determination of shallow site dynamic characteristics using seismic techniques in Suez city, Egypt

EGU General Assembly Conference Abstracts, Apr 1, 2019

NRIAG Journal of Astronomy and Geophysics, 2013

The shallow seismic refraction profiling was carried out at 18 sites in Tal El-Amarna, which is a... more The shallow seismic refraction profiling was carried out at 18 sites in Tal El-Amarna, which is a flat area on the eastern bank of the Nile River, 50 km south of El Minia Governorate, middle Egypt. The collected data are used to estimate the P-wave velocity and to delineate the nearsurface ground model beneath the study area. This study is supported by the National Research Institute of Astronomy and Geophysics due to the historical interest of the Tal El-Amarna area as a famous tourist place where there exist many Pharaoh temples and tombs. This area is low seismically active, but it is probably of high vulnerability due to the influence of the local geological conditions on earthquake ground motion, as well as the presence of poor constructions in the absence of various issues such as building designs, quality of building materials, etc. Another dataset at the study area is obtained by multi-channel passive source (microtremor) measurements, which have been recorded at four arrays. The frequency-wavenumber (f-k) method was used to derive the dispersion curves from the raw signals at each array. The resulted dispersion curves were inverted using the neighborhood algorithm to obtain the shear and P-wave velocity models. The concluded Vs and Vp values provide a preliminary estimation of the geotechnical parameters and site classification for the shallow soil as they are of great interest in civil engineering applications.

Acta Geophysica

The Sinai Peninsula is a subplate located between the African and Arabian plates. It is an import... more The Sinai Peninsula is a subplate located between the African and Arabian plates. It is an important subplate in the world; however, this region is poorly understood because of the shortage of geophysical data. Thus, this study focuses on built a three-dimensional (3D) high-resolution forward model of the crustal thickness with a new tectonic model and structural evaluation of the Sinai Peninsula to understand this area tectonically and determine its lithospheric and crustal thicknesses. Qualitative and quantitative interpretations of Bouguer gravity, reduced-to-the-pole (RTP) aeromagnetic, and earthquake data are explained to achieve the goals of this study. Two-dimensional (2D) interactive sequential modeling of gravity data is performed along with some well-selected profiles with existing crustal layer depth points from previous works in the studied region. Seventeen 2D models are constructed and used to determine the basement, Conrad (lower crust boundary), and Moho (upper mantl...

Soil susceptibility and opportunity to liquefaction phenomena during earthquakes

Depicting the main structural affected trends by operating aeromagnetic survey in the western part of Koraimat-Alzafarana road and surround area, Eastern Desert, Egypt

Modeling Earth Systems and Environment, 2021

Aeromagnetic data of the western part of Koraimat-Alzafarana road, Eastern Desert, Egypt is inter... more Aeromagnetic data of the western part of Koraimat-Alzafarana road, Eastern Desert, Egypt is interpreted to detect the subsurface structures that may resulted in presence of subsurface aquifer. To reach to the main target of this study, many procedures are done using some magnetic analysis techniques (e.g., technique of reduction to the magnetic pole, separation technique of regional-residual anomalies and edge detection methods). The results have been encouraging to merit further estimation of the magnetic depth and analyzing the trends of the study area. To increase the credibility, the depth is revised by the P-depth technique. The shallow and deep magnetic components are calculated to be 2046 and 5680 m. To ease the detection of the structure that encasing the study area and lack the rigorous analysis, reduced the magnetic pole map, residual map and 3D Euler deconvolution are integrated to depict the combined lineament map that prevailing tectonic pattern of the study area. Event...

Magnitude of completeness for the Northern stations of the Egyptian National Seismological Network

Arabian Journal of Geosciences

After the occurrence of an earthquake near Cairo on October 1992 (Mw 5.8), the Egyptian authoriti... more After the occurrence of an earthquake near Cairo on October 1992 (Mw 5.8), the Egyptian authorities established the Egyptian National Seismological Network (ENSN), which was targeted to monitor the seismic activity in and around Egypt. The ENSN started operation in 1997 with 66 stations installed by the National Research Institute of Astronomy and Geophysics (NRIAG). Almost 55,000 events were recorded up until 2018 since the time of ENSN’s operation. After more than 20 years of establishing ENSN, a scientific project was funded to review the detectability of the stations by different methods; so, the goal of this research is to evaluate the magnitude of completeness (Mc) which represents an important parameter for instrumental catalog studies using different catalog-based methods. The Mc is calculated based on deflection from the linear relation of frequency-magnitude of the recorded events in ENSN’s catalog. Calculation of Mc is indispensable for knowing and clarifying the seismicity parameters such as the b value in the Gutenberg-Richter equation. Three different methods were used, i.e., maximum curvature method (MAXC), b value stability approach (MBS), and entire magnitude range method (EMR). The results determine the variations among different methods, up to 0.5 magnitudes unit is observed. The importance of this study comes from its concentrate on the detectability of ENSN’s stations to show their efficiency for recording seismic events with high accuracy and for contributing in evaluation of seismic hazard in Egypt, in seismic engineering applications to mitigate earthquake risk, and in changing the position of bad recording stations to a quieter place with minimum noise level.

Active tectonic structures in northeastern Egypt: a geospatial analysis using structural, remote sensing, and seismic data

Arabian Journal of Geosciences

The seismotectonic activity in Northeastern Egypt is intimately related to the active tectonic st... more The seismotectonic activity in Northeastern Egypt is intimately related to the active tectonic structures (mainly faults) which deform the region and induce intraplate seismicity. The present contribution is a new attempt to integrate structural, remote sensing, and seismic data, and implement a reliable geospatial analysis to investigate and assess the nature of the relation between tectonic structures and seismotectonic activity in the Cairo–Suez district which is an active seismic source zone in Northeastern Egypt. The achieved remote sensing and GIS-based geospatial analysis introduces valuable information on the frequency, orientation, and density of investigated tectonic fault trends. The spatial distribution of earthquakes epicenters which recorded during the period (1997–2016) with magnitude (ML ≥ 3.0) is evidently interrelated with the detected tectonic trends, and normal faulting with subordinate shear component is the most focal mechanisms indicated from the analyzed seismic events. The depth analysis of the studied earthquakes suggests a “hard linkage” between the major rift-boundary faults in the northern Gulf of Suez rift and the tectonic trends in the southern domain of the Cairo–Suez district, and thus indicates seismic activity on relatively deeper crustal levels. Most of the studied earthquakes have occurred on the WNW–ESE to NW–SE oriented faults in predominantly extensional to transtensional stress regime, which indicating the WNW to NW tectonic trend as an active fault trend. The intraplate seismotectonic activity in Northeastern Egypt is highly controlled by two active tectonic boundaries, the Red Sea–Gulf of Suez rift and Aqaba–Dead Sea transform (to the east) and the Pelusium Shear System (PSS, to the west). Any reliable hypothetical model explaining the seismotectonic setting in such region would consider the Cairo–Suez district as a large transfer zone transmitting the “far-field” stresses northwestward to the PSS with an effective mechanism keeping the within-plate WNW–ESE, NW–SE, and E–W tectonic trends highly prone to rejuvenation and seismic rupture.

Site characterization using passive seismic techniques: A case of Suez city, Egypt

Journal of African Earth Sciences

Abstract This article introduces a site investigation study using quick and low-cost passive seis... more Abstract This article introduces a site investigation study using quick and low-cost passive seismic techniques at Suez city which located in the northeastern part of Egypt. The Spatial Auto Correlation (SPAC) method is applied, as well as the newly developed Centerless Circular Array (CCA) method for estimating the shear wave velocity (Vs) structures of the subsurface layers using microtremor array data. The Horizontal/Vertical Spectral Ratio (HVSR) approach is employed in determination of predominant frequency (f0) of a site and its equivalent peak amplitude of ground motion (A0) using a single station microtremor measurements. In this study, microtremor array measurements have been carried out at five sites distributed in Suez city. In order to cover a wide frequency band, different array sizes are carried out at each observation site. Measurements are made using high performance accelerometers with a sampling rate 100 sample per second. In both SPAC and CCA methods, only the vertical component of microtremor data is considered in the analysis. The analysis includes two main stages, i.e., calculation of surface wave dispersion curves and inversion process to infer the Vs structure of the ground. The obtained dispersion curves cover frequency band (2.0–21.0 Hz) and show a good fitting between the observed and the calculated ones at all measured sites, proving the reliability of the inversion process performed in this work. In HVSR analysis, the E-W, N-S, and vertical components of microtremors are considered, and the ratio between the horizontal and the vertical components spectra is calculated, then the spectral ratio curves are produced. The predominant frequency (f0) and the peak amplitude (A0) of HVSR curve are reported for each site of observation. The inferred Vs profiles are used for calculating the average velocity value of shear wave up to 30 m depth (AVS30) which in turn employed in site classification at the investigated area. The results demonstrate that the parameter AVS30 varies between 248 m/s and 310 m/s in Suez city. The created site classification incorporates only one class (Class D), appearing no significant variation in the characteristics of the superficial and shallow soils in Suez city. The site predominant frequency (f0) ranges between 0.35 Hz and 5.0 Hz with relevant amplification (A0) between 1.6 and 4.2. These outputs represent a crucial site response model for future seismic hazard assessment and risk decrease studies in Suez area which is currently witnesses large investments and rapid land use planning.

Moment tensor inversion of small-to-moderate size local earthquakes in Egypt

Journal of African Earth Sciences

Abstract Well resolved moment tensor solutions reveal information about the sources of seismic wa... more Abstract Well resolved moment tensor solutions reveal information about the sources of seismic waves. In this article, a waveform inversion technique, which uses waveform data from near-source seismic stations that belong to the Egyptian National Seismological Network (ENSN) is applied in order to estimate both focal mechanism and moment magnitude of small and moderate local earthquakes that occurred after 2010 till 2014 in and around Egypt. Fifty nine earthquakes with local magnitude (ML) ranging between 3.5 and 5.5 are analyzed. The earthquake focal mechanism obtained by waveform inversion was fundamentally validated by means of the basic technique of first onset polarities. Based on the obtained results, we identified several seismic sources in and around Egypt (i.e. Gulf of Aqaba, northern Gulf of Suez, southern Gulf of Suez-northern Red Sea, Aswan zone, Dahshour zone, and the passive continental margin). A combination of the newly estimated focal mechanisms and the previously published ones of earthquakes occurred before 2010 are used in determination of stress field for each relevant seismic source. A new scaling relationship between local magnitude (ML) and the estimated moment magnitude (Mw) has been developed using a linear regression. The results of this study may be used to improve the ENSN's stations configuration and the efficiency to record teleseismic and regional events.

Analysis of the similar epicenter earthquakes on 22 January 2013 and 01 June 2013, Central Gulf of Suez, Egypt

Journal of African Earth Sciences, 2016

Abstract On 22 January 2013 an earthquake with local magnitude ML 4.1 occurred in the central par... more Abstract On 22 January 2013 an earthquake with local magnitude ML 4.1 occurred in the central part of the Gulf of Suez. Six months later on 1 June 2013 another earthquake with local magnitude ML 5.1 took place at the same epicenter and different depths. These two perceptible events were recorded and localized by the Egyptian National Seismological Network (ENSN) and additional networks in the region. The purpose of this study is to determine focal mechanisms and source parameters of both earthquakes to analyze their tectonic relation. We determine the focal mechanisms by applying moment tensor inversion and first motion analysis of P- and S-waves. Both sources reveal oblique focal mechanisms with normal faulting and strike-slip components on differently oriented faults. The source mechanism of the larger event on 1 June in combination with the location of aftershock sequence indicates a left-lateral slip on N-S striking fault structure in 21 km depth that is in conformity with the NE-SW extensional Shmin (orientation of minimum horizontal compressional stress) and the local fault pattern. On the other hand, the smaller earthquake on 22 January with a shallower hypocenter in 16 km depth seems to have happened on a NE-SW striking fault plane sub-parallel to Shmin. Thus, here an energy release on a transfer fault connecting dominant rift-parallel structures might have resulted in a stress transfer, triggering the later ML 5.1 earthquake. Following Brune’s model and using displacement spectra, we calculate the dynamic source parameters for the two events. The estimated source parameters for the 22 January 2013 and 1 June 2013 earthquakes are fault length (470 and 830 m), stress drop (1.40 and 2.13 MPa), and seismic moment (5.47E+21 and 6.30E+22 dyn cm) corresponding to moment magnitudes of MW 3.8 and 4.6, respectively.

Source mechanism and parameters of the 19 October 2012 earthquake, northern Egyptian continental margin

Arabian Journal of Geosciences, 2016

The 19 October 2012 earthquake (ML = 5.1) occurred in the northern continental margin of Egypt wi... more The 19 October 2012 earthquake (ML = 5.1) occurred in the northern continental margin of Egypt within the Nile Cone at latitude 32.35° N and longitude 31.27° E. The quake was felt over a wide area in north Egypt and East Mediterranean countries, but no casualties have been reported. This area had experienced the large earthquake (Ms = 6.7) of 12 September 1955. The fault plane solution of the 19 October 2012 earthquake is here presented based on the digital seismograms recorded by the Egyptian National Seismological Network (ENSN) and other regional seismic stations. The analysis is carried out using the well-known techniques of first motion polarities of P-wave and the amplitude ratios of P-, SH-, and SV-waves with lower hemisphere projection. The fault plane solution based on the first P-wave onset demonstrates a left lateral strike-slip faulting mechanism, while the solution based on both P-wave polarities and amplitude ratios of P-, SH-, and SV-waves reveals a reverse fault with strike-slip component trending NW–SE to NE–SW, in conformity with the N–S compression along the Hellenic Arc convergence zone. Following the Brune’s model, the source dynamic parameters for the 19 October 2012 earthquake are estimated as corner frequency = 1.47 Hz, fault radius = 0.7 km, stress drop = 22.1 MPa, seismic moment = 2.80E + 16 Nm, and moment magnitude Mw = 4.9. These parameters may provide important quantitative information for the seismic hazard assessment studies.

Abu-Dabbab area is located in the western Red Sea coast at the Eastern Desert of Egypt. This area... more Abu-Dabbab area is located in the western Red Sea coast at the Eastern Desert of Egypt. This area is characterized by the presence of different geological units and high seismic activity. It is one of the seismic source zones in Egypt. The purpose of this research is the detection of the structural setting and rock units by using the Helicopter Electromagnetic (HEM) technique and its relation to the seismic activity at Abu-Dabbab area. The spatial distribution of earthquakes recorded by the Egyptian National Seismic Network (ENSN) was used to study the seismic activity along the detected structures at the study area. The results of this work show that there is a resistivity variation over the study area. This variation may be due to the difference in the rock composition and its conductivities. In addition, the places of high resistivity values clearly show sites of faults. The sites of approximated values confirm the presence and expansion of the different rock units which are mixe...

Earth Sciences Research Journal, 2014

An aeromagnetic reconnaissance study is presented to delineate the subsurface structure and tecto... more An aeromagnetic reconnaissance study is presented to delineate the subsurface structure and tectonic setting at the Fayoum-Cairo district, which experienced a damaging earthquake on October 12, 1992 of magnitude (M = 5.7). Analysis of aeromagnetic and seismicity data demonstrate three significant tectonic faults with trending to the NE-SW, NW-SE and E-W. The basement is uplifted in the northern and central parts with a depth of 1.3 km, and deepening in the southern part with a depth of 2.5 km. This is a seismically active zone and historically has experienced damaging earthquakes. In 1847, a damaging earthquake with maximum epicentral intensity (Modified Mercalli Intensity (MMI) = VII) was located there. On the eastern side, earthquake sources are well recognized at different locations. These sources created events of moderate size magnitude M < 5. The focal mechanisms of the major events from these sources are generally strike-slip with normal component. The focal mechanism of t...

NRIAG Journal of Astronomy and Geophysics, 2012

The aim of this paper is to study the ground vibrations using Nakamura technique to evaluate the ... more The aim of this paper is to study the ground vibrations using Nakamura technique to evaluate the relation between the ground conditions and the earthquake characteristics. Microtremor measurements were carried out at 55 sites in and around Zagazig city. The signals were processed using horizontal to vertical spectral ratio (HVSR) technique to estimate the fundamental frequencies of the soil deposits and its corresponding H/V amplitude. Seismic measurements were acquired at nine sites for recording the surface waves. The recorded waveforms were processed using the multi-channel analysis of surface waves (MASW) method to infer the shear wave velocity profile. The obtained fundamental frequencies were found to be ranging from 0.7 to 1.7 Hz and the maximum H/V amplitude reached 6.4. These results together with the average shear wave velocity in the surface layers were used for the estimation of the thickness of the upper most soft cover layers (depth to bedrock). The sediment thickness generally increases at the northeastern and southwestern parts of the area which is in good agreement with the local geological structure. The results of this work showed the zones of higher potential damage in the event of an earthquake in the study area.

NRIAG Journal of Astronomy and Geophysics

This article aims to simulate the ground motion parameters of the moderate magnitude (M L 5.1) Ju... more This article aims to simulate the ground motion parameters of the moderate magnitude (M L 5.1) June 1, 2013 Gulf of Suez earthquake, which represents the largest instrumental earthquake to be recorded in the middle part of the Gulf of Suez up to now. This event was felt in all cities located on both sides of the Gulf of Suez, with minor damage to property near the epicenter; however, no casualties were observed. The stochastic technique with the site-dependent spectral model is used to simulate the strong ground motion parameters of this earthquake in the cities located at the western side of the Gulf of Suez and north Red Sea namely: Suez, Ain Sokhna, Zafarana, Ras Gharib, and Hurghada. The presence of many tourist resorts and the increase in land use planning in the considered cities represent the motivation of the current study. The simulated parameters comprise the Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), and Peak Ground Displacement (PGD), in addition to Pseudo Spectral Acceleration (PSA). The model developed for ground motion simulation is validated by using the recordings of three accelerographs installed around the epicenter of the investigated earthquake. Depending on the site effect that has been determined in the investigated areas by using geotechnical data (e.g., shear wave velocities and microtremor recordings), the investigated areas are classified into two zones (A and B). Zone A is characterized by higher site amplification than Zone B. The ground motion parameters are simulated at each zone in the considered areas. The results reveal that the highest values of PGA, PGV, and PGD are observed at Ras Gharib city (epicentral distance $ 11 km) as 67 cm/s 2 , 2.53 cm/s, and 0.45 cm respectively for Zone A, and as 26.5 cm/s 2 , 1.0 cm/s, and 0.2 cm respectively for Zone B, while the lowest values of PGA, PGV, and PGD are observed at Suez city (epicentral distance $ 190 km) as 3.0 cm/s 2 , 0.2 cm/s, and 0.05 cm/s respectively for Zone A, and as 1.3 cm/s 2 , 0.1 cm/s, and 0.024 cm respectively for Zone B. Also the highest PSA values are observed in Ras Gharib city as 200 cm/s 2 and 78 cm/s 2 for Zone A and Zone B respectively, while the lowest PSA values are observed in Suez city as 7 cm/s 2 and

An aeromagnetic reconnaissance study is presented to delineate the subsurface structure and tecto... more An aeromagnetic reconnaissance study is presented to delineate the subsurface structure and tectonic setting at the Fayoum-Cairo district, which experienced a damaging earthquake on October 12, 1992 of magnitude (M = 5.7). Analysis of aeromagnetic and seismicity data demonstrate three significant tectonic faults with trending to the NE-SW, NW-SE and E-W. The basement is uplifted in the northern and central parts with a depth of 1.3 km, and deepening in the southern part with a depth of 2.5 km. This is a seismically active zone and historically has experienced damaging earthquakes. In 1847, a damaging earthquake with maximum epicentral intensity (Modified Mercalli Intensity (MMI) = VII) was located there. On the eastern side, earthquake sources are well recognized at different locations. These sources created events of moderate size magnitude M < 5. The focal mechanisms of the major events from these sources are generally strike-slip with normal component. The focal mechanism of t...

Areal-Source and Fault-Source Based Probabilistic Seismic Hazard Analysis Using Characteristic Earthquake Model and Monte-Carlo Approach: An Example of the Gulf of Aqaba Region

Seismicity and Seismotectonic of North Africa: An Updated Review

Regional geology reviews, 2024

Journal of Applied Geophysics (Cairo)

The Egyptian government is active in multiple areas designated for industry and urban development... more The Egyptian government is active in multiple areas designated for industry and urban development on the outskirts of both the capital and various governorates within newly established cities. The proposed site for the creation of the industrial zone of New-Cairo City is regarded one of Egypt's most promising commercial and combined services zones. The study's primary goal is to map the region's subsurface geological conditions and interpret the findings for geotechnical qualities of the underlying materials. The study aims to evaluate the properties of the subsurface layers to determine their suitability for construction and engineering purposes. The study is a case study that focuses specifically on the combined services area of Madinaty, to assess the suitability of the subsurface layers for geotechnical engineering purposes. To gather data about the subsurface layers, the investigation employed two geophysical techniques: Electrical Resistivity Tomography (ERT) and Shallow Seismic Refraction (SSR). SSR is used in the study area to identify dynamic geotechnical characteristics of the base layers using the P-wave and S-wave velocities. Two sub-surface layers are identified based on the velocity values of the Geo-seismic layers. The first layer is composed of mixed soil of sand, clay, and gravel, where the second layer composes of hard Limestone. According to all the criteria, regarding engineering aims, the area is divided into high, moderate, and low competent-material zones with varying degrees of fittingness. The current study suggested sorting the fundamental subsurface materials in the high and moderate zone for engineering purposes.

Indian Geotechnical Journal, 2017

A moderate earthquake (Ms = 5.8) was occurred on October 12, 1992 at about 25 km south west of Ca... more A moderate earthquake (Ms = 5.8) was occurred on October 12, 1992 at about 25 km south west of Cairo city-Egypt. It caused large damage to numerous poorly constructed buildings. One of the important seismological phenomenon happened during the earthquake is the soil liquefaction which was associated usually with the occurrence of big sand-boils near the epicenter of the earthquake. Recently different methods are used to reevaluate the liquefaction potentiality, in this study five different sites that showed high liquefaction potentiality during Cairo earthquake, have been selected to be studied to for re-evaluate liquefaction potentiality in Egypt. Shear wave velocity determination provides a promising tool to calculate the factor of safety (FS) against liquefaction, and resistance evaluation of sandy soils against this phenomenon. Multi-channel analysis of surface wave method as an efficient tool and is here used to infer the velocity profile at the considered sites to be used as input for the calculation of FS as an indication for liquefaction potentiality. The aim of this study is to determine the potentiality of liquefaction phenomenon in the selected sites to be one of soil characteristics input for any further hazard study. The selected five sites are named: Aquaz, Atf, Bedsa, El-Gammal, Zaweit Dahshour showed a liquefaction liquation during the 1992 Cairo earthquake which forced us to reevaluate and update our knowledge through the recent technique about the liquefaction potentiality at these sites. The FS obtained by using shear wave was compared with the values obtained from SPT from previous studies.

Determination of shallow site dynamic characteristics using seismic techniques in Suez city, Egypt

EGU General Assembly Conference Abstracts, Apr 1, 2019

NRIAG Journal of Astronomy and Geophysics, 2013

The shallow seismic refraction profiling was carried out at 18 sites in Tal El-Amarna, which is a... more The shallow seismic refraction profiling was carried out at 18 sites in Tal El-Amarna, which is a flat area on the eastern bank of the Nile River, 50 km south of El Minia Governorate, middle Egypt. The collected data are used to estimate the P-wave velocity and to delineate the nearsurface ground model beneath the study area. This study is supported by the National Research Institute of Astronomy and Geophysics due to the historical interest of the Tal El-Amarna area as a famous tourist place where there exist many Pharaoh temples and tombs. This area is low seismically active, but it is probably of high vulnerability due to the influence of the local geological conditions on earthquake ground motion, as well as the presence of poor constructions in the absence of various issues such as building designs, quality of building materials, etc. Another dataset at the study area is obtained by multi-channel passive source (microtremor) measurements, which have been recorded at four arrays. The frequency-wavenumber (f-k) method was used to derive the dispersion curves from the raw signals at each array. The resulted dispersion curves were inverted using the neighborhood algorithm to obtain the shear and P-wave velocity models. The concluded Vs and Vp values provide a preliminary estimation of the geotechnical parameters and site classification for the shallow soil as they are of great interest in civil engineering applications.

Acta Geophysica

The Sinai Peninsula is a subplate located between the African and Arabian plates. It is an import... more The Sinai Peninsula is a subplate located between the African and Arabian plates. It is an important subplate in the world; however, this region is poorly understood because of the shortage of geophysical data. Thus, this study focuses on built a three-dimensional (3D) high-resolution forward model of the crustal thickness with a new tectonic model and structural evaluation of the Sinai Peninsula to understand this area tectonically and determine its lithospheric and crustal thicknesses. Qualitative and quantitative interpretations of Bouguer gravity, reduced-to-the-pole (RTP) aeromagnetic, and earthquake data are explained to achieve the goals of this study. Two-dimensional (2D) interactive sequential modeling of gravity data is performed along with some well-selected profiles with existing crustal layer depth points from previous works in the studied region. Seventeen 2D models are constructed and used to determine the basement, Conrad (lower crust boundary), and Moho (upper mantl...

Soil susceptibility and opportunity to liquefaction phenomena during earthquakes

Depicting the main structural affected trends by operating aeromagnetic survey in the western part of Koraimat-Alzafarana road and surround area, Eastern Desert, Egypt

Modeling Earth Systems and Environment, 2021

Aeromagnetic data of the western part of Koraimat-Alzafarana road, Eastern Desert, Egypt is inter... more Aeromagnetic data of the western part of Koraimat-Alzafarana road, Eastern Desert, Egypt is interpreted to detect the subsurface structures that may resulted in presence of subsurface aquifer. To reach to the main target of this study, many procedures are done using some magnetic analysis techniques (e.g., technique of reduction to the magnetic pole, separation technique of regional-residual anomalies and edge detection methods). The results have been encouraging to merit further estimation of the magnetic depth and analyzing the trends of the study area. To increase the credibility, the depth is revised by the P-depth technique. The shallow and deep magnetic components are calculated to be 2046 and 5680 m. To ease the detection of the structure that encasing the study area and lack the rigorous analysis, reduced the magnetic pole map, residual map and 3D Euler deconvolution are integrated to depict the combined lineament map that prevailing tectonic pattern of the study area. Event...

Magnitude of completeness for the Northern stations of the Egyptian National Seismological Network

Arabian Journal of Geosciences

After the occurrence of an earthquake near Cairo on October 1992 (Mw 5.8), the Egyptian authoriti... more After the occurrence of an earthquake near Cairo on October 1992 (Mw 5.8), the Egyptian authorities established the Egyptian National Seismological Network (ENSN), which was targeted to monitor the seismic activity in and around Egypt. The ENSN started operation in 1997 with 66 stations installed by the National Research Institute of Astronomy and Geophysics (NRIAG). Almost 55,000 events were recorded up until 2018 since the time of ENSN’s operation. After more than 20 years of establishing ENSN, a scientific project was funded to review the detectability of the stations by different methods; so, the goal of this research is to evaluate the magnitude of completeness (Mc) which represents an important parameter for instrumental catalog studies using different catalog-based methods. The Mc is calculated based on deflection from the linear relation of frequency-magnitude of the recorded events in ENSN’s catalog. Calculation of Mc is indispensable for knowing and clarifying the seismicity parameters such as the b value in the Gutenberg-Richter equation. Three different methods were used, i.e., maximum curvature method (MAXC), b value stability approach (MBS), and entire magnitude range method (EMR). The results determine the variations among different methods, up to 0.5 magnitudes unit is observed. The importance of this study comes from its concentrate on the detectability of ENSN’s stations to show their efficiency for recording seismic events with high accuracy and for contributing in evaluation of seismic hazard in Egypt, in seismic engineering applications to mitigate earthquake risk, and in changing the position of bad recording stations to a quieter place with minimum noise level.

Active tectonic structures in northeastern Egypt: a geospatial analysis using structural, remote sensing, and seismic data

Arabian Journal of Geosciences

The seismotectonic activity in Northeastern Egypt is intimately related to the active tectonic st... more The seismotectonic activity in Northeastern Egypt is intimately related to the active tectonic structures (mainly faults) which deform the region and induce intraplate seismicity. The present contribution is a new attempt to integrate structural, remote sensing, and seismic data, and implement a reliable geospatial analysis to investigate and assess the nature of the relation between tectonic structures and seismotectonic activity in the Cairo–Suez district which is an active seismic source zone in Northeastern Egypt. The achieved remote sensing and GIS-based geospatial analysis introduces valuable information on the frequency, orientation, and density of investigated tectonic fault trends. The spatial distribution of earthquakes epicenters which recorded during the period (1997–2016) with magnitude (ML ≥ 3.0) is evidently interrelated with the detected tectonic trends, and normal faulting with subordinate shear component is the most focal mechanisms indicated from the analyzed seismic events. The depth analysis of the studied earthquakes suggests a “hard linkage” between the major rift-boundary faults in the northern Gulf of Suez rift and the tectonic trends in the southern domain of the Cairo–Suez district, and thus indicates seismic activity on relatively deeper crustal levels. Most of the studied earthquakes have occurred on the WNW–ESE to NW–SE oriented faults in predominantly extensional to transtensional stress regime, which indicating the WNW to NW tectonic trend as an active fault trend. The intraplate seismotectonic activity in Northeastern Egypt is highly controlled by two active tectonic boundaries, the Red Sea–Gulf of Suez rift and Aqaba–Dead Sea transform (to the east) and the Pelusium Shear System (PSS, to the west). Any reliable hypothetical model explaining the seismotectonic setting in such region would consider the Cairo–Suez district as a large transfer zone transmitting the “far-field” stresses northwestward to the PSS with an effective mechanism keeping the within-plate WNW–ESE, NW–SE, and E–W tectonic trends highly prone to rejuvenation and seismic rupture.

Site characterization using passive seismic techniques: A case of Suez city, Egypt

Journal of African Earth Sciences

Abstract This article introduces a site investigation study using quick and low-cost passive seis... more Abstract This article introduces a site investigation study using quick and low-cost passive seismic techniques at Suez city which located in the northeastern part of Egypt. The Spatial Auto Correlation (SPAC) method is applied, as well as the newly developed Centerless Circular Array (CCA) method for estimating the shear wave velocity (Vs) structures of the subsurface layers using microtremor array data. The Horizontal/Vertical Spectral Ratio (HVSR) approach is employed in determination of predominant frequency (f0) of a site and its equivalent peak amplitude of ground motion (A0) using a single station microtremor measurements. In this study, microtremor array measurements have been carried out at five sites distributed in Suez city. In order to cover a wide frequency band, different array sizes are carried out at each observation site. Measurements are made using high performance accelerometers with a sampling rate 100 sample per second. In both SPAC and CCA methods, only the vertical component of microtremor data is considered in the analysis. The analysis includes two main stages, i.e., calculation of surface wave dispersion curves and inversion process to infer the Vs structure of the ground. The obtained dispersion curves cover frequency band (2.0–21.0 Hz) and show a good fitting between the observed and the calculated ones at all measured sites, proving the reliability of the inversion process performed in this work. In HVSR analysis, the E-W, N-S, and vertical components of microtremors are considered, and the ratio between the horizontal and the vertical components spectra is calculated, then the spectral ratio curves are produced. The predominant frequency (f0) and the peak amplitude (A0) of HVSR curve are reported for each site of observation. The inferred Vs profiles are used for calculating the average velocity value of shear wave up to 30 m depth (AVS30) which in turn employed in site classification at the investigated area. The results demonstrate that the parameter AVS30 varies between 248 m/s and 310 m/s in Suez city. The created site classification incorporates only one class (Class D), appearing no significant variation in the characteristics of the superficial and shallow soils in Suez city. The site predominant frequency (f0) ranges between 0.35 Hz and 5.0 Hz with relevant amplification (A0) between 1.6 and 4.2. These outputs represent a crucial site response model for future seismic hazard assessment and risk decrease studies in Suez area which is currently witnesses large investments and rapid land use planning.

Moment tensor inversion of small-to-moderate size local earthquakes in Egypt

Journal of African Earth Sciences

Abstract Well resolved moment tensor solutions reveal information about the sources of seismic wa... more Abstract Well resolved moment tensor solutions reveal information about the sources of seismic waves. In this article, a waveform inversion technique, which uses waveform data from near-source seismic stations that belong to the Egyptian National Seismological Network (ENSN) is applied in order to estimate both focal mechanism and moment magnitude of small and moderate local earthquakes that occurred after 2010 till 2014 in and around Egypt. Fifty nine earthquakes with local magnitude (ML) ranging between 3.5 and 5.5 are analyzed. The earthquake focal mechanism obtained by waveform inversion was fundamentally validated by means of the basic technique of first onset polarities. Based on the obtained results, we identified several seismic sources in and around Egypt (i.e. Gulf of Aqaba, northern Gulf of Suez, southern Gulf of Suez-northern Red Sea, Aswan zone, Dahshour zone, and the passive continental margin). A combination of the newly estimated focal mechanisms and the previously published ones of earthquakes occurred before 2010 are used in determination of stress field for each relevant seismic source. A new scaling relationship between local magnitude (ML) and the estimated moment magnitude (Mw) has been developed using a linear regression. The results of this study may be used to improve the ENSN's stations configuration and the efficiency to record teleseismic and regional events.

Analysis of the similar epicenter earthquakes on 22 January 2013 and 01 June 2013, Central Gulf of Suez, Egypt

Journal of African Earth Sciences, 2016

Abstract On 22 January 2013 an earthquake with local magnitude ML 4.1 occurred in the central par... more Abstract On 22 January 2013 an earthquake with local magnitude ML 4.1 occurred in the central part of the Gulf of Suez. Six months later on 1 June 2013 another earthquake with local magnitude ML 5.1 took place at the same epicenter and different depths. These two perceptible events were recorded and localized by the Egyptian National Seismological Network (ENSN) and additional networks in the region. The purpose of this study is to determine focal mechanisms and source parameters of both earthquakes to analyze their tectonic relation. We determine the focal mechanisms by applying moment tensor inversion and first motion analysis of P- and S-waves. Both sources reveal oblique focal mechanisms with normal faulting and strike-slip components on differently oriented faults. The source mechanism of the larger event on 1 June in combination with the location of aftershock sequence indicates a left-lateral slip on N-S striking fault structure in 21 km depth that is in conformity with the NE-SW extensional Shmin (orientation of minimum horizontal compressional stress) and the local fault pattern. On the other hand, the smaller earthquake on 22 January with a shallower hypocenter in 16 km depth seems to have happened on a NE-SW striking fault plane sub-parallel to Shmin. Thus, here an energy release on a transfer fault connecting dominant rift-parallel structures might have resulted in a stress transfer, triggering the later ML 5.1 earthquake. Following Brune’s model and using displacement spectra, we calculate the dynamic source parameters for the two events. The estimated source parameters for the 22 January 2013 and 1 June 2013 earthquakes are fault length (470 and 830 m), stress drop (1.40 and 2.13 MPa), and seismic moment (5.47E+21 and 6.30E+22 dyn cm) corresponding to moment magnitudes of MW 3.8 and 4.6, respectively.

Source mechanism and parameters of the 19 October 2012 earthquake, northern Egyptian continental margin

Arabian Journal of Geosciences, 2016

The 19 October 2012 earthquake (ML = 5.1) occurred in the northern continental margin of Egypt wi... more The 19 October 2012 earthquake (ML = 5.1) occurred in the northern continental margin of Egypt within the Nile Cone at latitude 32.35° N and longitude 31.27° E. The quake was felt over a wide area in north Egypt and East Mediterranean countries, but no casualties have been reported. This area had experienced the large earthquake (Ms = 6.7) of 12 September 1955. The fault plane solution of the 19 October 2012 earthquake is here presented based on the digital seismograms recorded by the Egyptian National Seismological Network (ENSN) and other regional seismic stations. The analysis is carried out using the well-known techniques of first motion polarities of P-wave and the amplitude ratios of P-, SH-, and SV-waves with lower hemisphere projection. The fault plane solution based on the first P-wave onset demonstrates a left lateral strike-slip faulting mechanism, while the solution based on both P-wave polarities and amplitude ratios of P-, SH-, and SV-waves reveals a reverse fault with strike-slip component trending NW–SE to NE–SW, in conformity with the N–S compression along the Hellenic Arc convergence zone. Following the Brune’s model, the source dynamic parameters for the 19 October 2012 earthquake are estimated as corner frequency = 1.47 Hz, fault radius = 0.7 km, stress drop = 22.1 MPa, seismic moment = 2.80E + 16 Nm, and moment magnitude Mw = 4.9. These parameters may provide important quantitative information for the seismic hazard assessment studies.

Abu-Dabbab area is located in the western Red Sea coast at the Eastern Desert of Egypt. This area... more Abu-Dabbab area is located in the western Red Sea coast at the Eastern Desert of Egypt. This area is characterized by the presence of different geological units and high seismic activity. It is one of the seismic source zones in Egypt. The purpose of this research is the detection of the structural setting and rock units by using the Helicopter Electromagnetic (HEM) technique and its relation to the seismic activity at Abu-Dabbab area. The spatial distribution of earthquakes recorded by the Egyptian National Seismic Network (ENSN) was used to study the seismic activity along the detected structures at the study area. The results of this work show that there is a resistivity variation over the study area. This variation may be due to the difference in the rock composition and its conductivities. In addition, the places of high resistivity values clearly show sites of faults. The sites of approximated values confirm the presence and expansion of the different rock units which are mixe...

Earth Sciences Research Journal, 2014

An aeromagnetic reconnaissance study is presented to delineate the subsurface structure and tecto... more An aeromagnetic reconnaissance study is presented to delineate the subsurface structure and tectonic setting at the Fayoum-Cairo district, which experienced a damaging earthquake on October 12, 1992 of magnitude (M = 5.7). Analysis of aeromagnetic and seismicity data demonstrate three significant tectonic faults with trending to the NE-SW, NW-SE and E-W. The basement is uplifted in the northern and central parts with a depth of 1.3 km, and deepening in the southern part with a depth of 2.5 km. This is a seismically active zone and historically has experienced damaging earthquakes. In 1847, a damaging earthquake with maximum epicentral intensity (Modified Mercalli Intensity (MMI) = VII) was located there. On the eastern side, earthquake sources are well recognized at different locations. These sources created events of moderate size magnitude M < 5. The focal mechanisms of the major events from these sources are generally strike-slip with normal component. The focal mechanism of t...

NRIAG Journal of Astronomy and Geophysics, 2012

The aim of this paper is to study the ground vibrations using Nakamura technique to evaluate the ... more The aim of this paper is to study the ground vibrations using Nakamura technique to evaluate the relation between the ground conditions and the earthquake characteristics. Microtremor measurements were carried out at 55 sites in and around Zagazig city. The signals were processed using horizontal to vertical spectral ratio (HVSR) technique to estimate the fundamental frequencies of the soil deposits and its corresponding H/V amplitude. Seismic measurements were acquired at nine sites for recording the surface waves. The recorded waveforms were processed using the multi-channel analysis of surface waves (MASW) method to infer the shear wave velocity profile. The obtained fundamental frequencies were found to be ranging from 0.7 to 1.7 Hz and the maximum H/V amplitude reached 6.4. These results together with the average shear wave velocity in the surface layers were used for the estimation of the thickness of the upper most soft cover layers (depth to bedrock). The sediment thickness generally increases at the northeastern and southwestern parts of the area which is in good agreement with the local geological structure. The results of this work showed the zones of higher potential damage in the event of an earthquake in the study area.

NRIAG Journal of Astronomy and Geophysics

This article aims to simulate the ground motion parameters of the moderate magnitude (M L 5.1) Ju... more This article aims to simulate the ground motion parameters of the moderate magnitude (M L 5.1) June 1, 2013 Gulf of Suez earthquake, which represents the largest instrumental earthquake to be recorded in the middle part of the Gulf of Suez up to now. This event was felt in all cities located on both sides of the Gulf of Suez, with minor damage to property near the epicenter; however, no casualties were observed. The stochastic technique with the site-dependent spectral model is used to simulate the strong ground motion parameters of this earthquake in the cities located at the western side of the Gulf of Suez and north Red Sea namely: Suez, Ain Sokhna, Zafarana, Ras Gharib, and Hurghada. The presence of many tourist resorts and the increase in land use planning in the considered cities represent the motivation of the current study. The simulated parameters comprise the Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), and Peak Ground Displacement (PGD), in addition to Pseudo Spectral Acceleration (PSA). The model developed for ground motion simulation is validated by using the recordings of three accelerographs installed around the epicenter of the investigated earthquake. Depending on the site effect that has been determined in the investigated areas by using geotechnical data (e.g., shear wave velocities and microtremor recordings), the investigated areas are classified into two zones (A and B). Zone A is characterized by higher site amplification than Zone B. The ground motion parameters are simulated at each zone in the considered areas. The results reveal that the highest values of PGA, PGV, and PGD are observed at Ras Gharib city (epicentral distance $ 11 km) as 67 cm/s 2 , 2.53 cm/s, and 0.45 cm respectively for Zone A, and as 26.5 cm/s 2 , 1.0 cm/s, and 0.2 cm respectively for Zone B, while the lowest values of PGA, PGV, and PGD are observed at Suez city (epicentral distance $ 190 km) as 3.0 cm/s 2 , 0.2 cm/s, and 0.05 cm/s respectively for Zone A, and as 1.3 cm/s 2 , 0.1 cm/s, and 0.024 cm respectively for Zone B. Also the highest PSA values are observed in Ras Gharib city as 200 cm/s 2 and 78 cm/s 2 for Zone A and Zone B respectively, while the lowest PSA values are observed in Suez city as 7 cm/s 2 and

An aeromagnetic reconnaissance study is presented to delineate the subsurface structure and tecto... more An aeromagnetic reconnaissance study is presented to delineate the subsurface structure and tectonic setting at the Fayoum-Cairo district, which experienced a damaging earthquake on October 12, 1992 of magnitude (M = 5.7). Analysis of aeromagnetic and seismicity data demonstrate three significant tectonic faults with trending to the NE-SW, NW-SE and E-W. The basement is uplifted in the northern and central parts with a depth of 1.3 km, and deepening in the southern part with a depth of 2.5 km. This is a seismically active zone and historically has experienced damaging earthquakes. In 1847, a damaging earthquake with maximum epicentral intensity (Modified Mercalli Intensity (MMI) = VII) was located there. On the eastern side, earthquake sources are well recognized at different locations. These sources created events of moderate size magnitude M < 5. The focal mechanisms of the major events from these sources are generally strike-slip with normal component. The focal mechanism of t...