Abstract The Arabian Plate is surrounded by regions of relatively high seismicity. Accounting for... more Abstract The Arabian Plate is surrounded by regions of relatively high seismicity. Accounting for this seismicity is of great importance for seismic hazard and risk assessments, seismic zoning, and land use. In this study, a homogenous earthquake catalogue of moment-magnitude (Mw) for the Arabian Plate is provided. The comprehensive and homogenous earthquake catalogue provided in the current study spatially involves the entire Arabian Peninsula and neighboring areas, covering all earthquake sources that can generate substantial hazard for the Arabian Plate mainland. The catalogue extends in time from 19 to 2015 with a total number of 13,156 events, of which 497 are historical events. Four polygons covering the entire Arabian Plate were delineated and different data sources including special studies, local, regional and international catalogues were used to prepare the earthquake catalogue. Moment magnitudes (Mw) that provided by original sources were given the highest magnitude type priority and introduced to the catalogues with their references. Earthquakes with magnitude differ from Mw were converted into this scale applying empirical relationships derived in the current or in previous studies. The four polygons catalogues were included in two comprehensive earthquake catalogues constituting the historical and instrumental periods. Duplicate events were identified and discarded from the current catalogue. The present earthquake catalogue was declustered in order to contain only independent events and investigated for the completeness with time of different magnitude spans.
Abstract The objective of this study is to evaluate the seismic hazard at the northwestern Egypt ... more Abstract The objective of this study is to evaluate the seismic hazard at the northwestern Egypt using the probabilistic seismic hazard assessment approach. The Probabilistic approach was carried out based on a recent data set to take into account the historic seismicity and updated instrumental seismicity. A homogenous earthquake catalogue was compiled and a proposed seismic sources model was presented. The doubly-truncated exponential model was adopted for calculations of the recurrence parameters. Ground-motion prediction equations that recently recommended by experts and developed based upon earthquake data obtained from tectonic environments similar to those in and around the studied area were weighted and used for assessment of seismic hazard in the frame of logic tree approach. Considering a grid of 0.2° × 0.2° covering the study area, seismic hazard curves for every node were calculated. Hazard maps at bedrock conditions were produced for peak ground acceleration, in addition to six spectral periods (0.1, 0.2, 0.3, 1.0, 2.0 and 3.0 s) for return periods of 72, 475 and 2475 years. The unified hazard spectra of two selected rock sites at Alexandria and Mersa Matruh Cities were provided. Finally, the hazard curves were de-aggregated to determine the sources that contribute most of hazard level of 10% probability of exceedance in 50 years for the mentioned selected sites.
The earthquakes epicenters and the mechanism for recent earthquakes around the Nile Valley in Egy... more The earthquakes epicenters and the mechanism for recent earthquakes around the Nile Valley in Egypt were utilized to evaluate the stress regime around the Egyptian Nile Valley. Five seismic zones around the Nile valley are constructed. These zones are: the N-E Cairo, S-W Cairo, Beni Swief, S-E Assuit and Aswan area. In the frame of Tensor program the improved Right Dihedron Method by Delvaux and Sperner (2003) was applied to evaluate the orientation of the principle stress axes and the shape of the stress tensor for the proposed seismic zones. It showed the heterogeneous stress regime around the Nile valley. In the N-E Cairo seismic zone the stress regime is extensional, but in the S-W Cairo seismic source, the stress regime is different, where the strike slip component is present. Beni Swief Seismic zone, in the North Eastern part, was characterized by extensional stress regime. Around the Nile Valley, In the Middle Egypt, the stress regime is pure strike slip, while in the Aswan a...
ABSTRACT The large tsunamigenic earthquake that shook the eastern Mediterranean in the second hal... more ABSTRACT The large tsunamigenic earthquake that shook the eastern Mediterranean in the second half of the 4th century AD with a magnitude which is only roughly estimated as being of at least 8 has been considered as one of the largest earthquakes ever reported in the Mediterranean Sea. A general consensus exists that it occurred on 21 July 365 in the western Hellenic Arc causing a co-seismic uplift in western Crete up to c. 9 m. However, the rupture zone is not well constrained so far. From historical and geological documentation it has been supported that the tsunami inundated not only in near-field but also in remote coastal sites in the entire basin of the Mediterranean. We reexamine critically the available documentary sources and geological information, create an inventory of the most credible coastal sites to have inundated and conclude that the tsunami propagation zone very likely was less than what was considered so far. From dislocation modeling scenarios we reproduce several candidate seismic sources and simulate numerically the resulting tsunami. Then, calculated tsunami wave heights and runups are compared with the observed ones in credible coastal sites to determine the most candidate rupture zone of the earthquake. Implications of such a determination for the tsunami hazard assessment particularly for the West Hellenic Arc as well as for Alexandria is of great interest since there is the most reliable description of tsunami impact. Finally, by extending probabilistic hazard assessment from earthquakes to tsunamis we perform tsunami hazard assessment for Alexandria for a future 365-type tsunami by employing a combination of probability evaluation of earthquakes in the tectonic segment that generated the 365 event and of the tsunami numerical simulation.
The objective of this study is to evaluate the seismic hazard at the northwestern Egypt using the... more The objective of this study is to evaluate the seismic hazard at the northwestern Egypt using the probabilistic seismic hazard assessment approach. The Probabilistic approach was carried out based on a recent data set to take into account the historic seismicity and updated instrumental seismicity. A homogenous earthquake catalogue was compiled and a proposed seismic sources model was presented. The doubly-truncated exponential model was adopted for calculations of the recurrence parameters. Ground-motion prediction equations that recently recommended by experts and developed based upon earthquake data obtained from tectonic environments similar to those in and around the studied area were weighted and used for assessment of seismic hazard in the frame of logic tree approach. Considering a grid of 0.2 Â 0.2 covering the study area, seismic hazard curves for every node were calculated. Hazard maps at bedrock conditions were produced for peak ground acceleration, in addition to six spectral periods (0.1, 0.2, 0.3, 1.0, 2.0 and 3.0 s) for return periods of 72, 475 and 2475 years. The unified hazard spectra of two selected rock sites at Alexandria and Mersa Matruh Cities were provided. Finally, the hazard curves were de-aggregated to determine the sources that contribute most of hazard level of 10% probability of exceedance in 50 years for the mentioned selected sites.
Abstract The Arabian Plate is surrounded by regions of relatively high seismicity. Accounting for... more Abstract The Arabian Plate is surrounded by regions of relatively high seismicity. Accounting for this seismicity is of great importance for seismic hazard and risk assessments, seismic zoning, and land use. In this study, a homogenous earthquake catalogue of moment-magnitude (Mw) for the Arabian Plate is provided. The comprehensive and homogenous earthquake catalogue provided in the current study spatially involves the entire Arabian Peninsula and neighboring areas, covering all earthquake sources that can generate substantial hazard for the Arabian Plate mainland. The catalogue extends in time from 19 to 2015 with a total number of 13,156 events, of which 497 are historical events. Four polygons covering the entire Arabian Plate were delineated and different data sources including special studies, local, regional and international catalogues were used to prepare the earthquake catalogue. Moment magnitudes (Mw) that provided by original sources were given the highest magnitude type priority and introduced to the catalogues with their references. Earthquakes with magnitude differ from Mw were converted into this scale applying empirical relationships derived in the current or in previous studies. The four polygons catalogues were included in two comprehensive earthquake catalogues constituting the historical and instrumental periods. Duplicate events were identified and discarded from the current catalogue. The present earthquake catalogue was declustered in order to contain only independent events and investigated for the completeness with time of different magnitude spans.
Abstract The objective of this study is to evaluate the seismic hazard at the northwestern Egypt ... more Abstract The objective of this study is to evaluate the seismic hazard at the northwestern Egypt using the probabilistic seismic hazard assessment approach. The Probabilistic approach was carried out based on a recent data set to take into account the historic seismicity and updated instrumental seismicity. A homogenous earthquake catalogue was compiled and a proposed seismic sources model was presented. The doubly-truncated exponential model was adopted for calculations of the recurrence parameters. Ground-motion prediction equations that recently recommended by experts and developed based upon earthquake data obtained from tectonic environments similar to those in and around the studied area were weighted and used for assessment of seismic hazard in the frame of logic tree approach. Considering a grid of 0.2° × 0.2° covering the study area, seismic hazard curves for every node were calculated. Hazard maps at bedrock conditions were produced for peak ground acceleration, in addition to six spectral periods (0.1, 0.2, 0.3, 1.0, 2.0 and 3.0 s) for return periods of 72, 475 and 2475 years. The unified hazard spectra of two selected rock sites at Alexandria and Mersa Matruh Cities were provided. Finally, the hazard curves were de-aggregated to determine the sources that contribute most of hazard level of 10% probability of exceedance in 50 years for the mentioned selected sites.
The earthquakes epicenters and the mechanism for recent earthquakes around the Nile Valley in Egy... more The earthquakes epicenters and the mechanism for recent earthquakes around the Nile Valley in Egypt were utilized to evaluate the stress regime around the Egyptian Nile Valley. Five seismic zones around the Nile valley are constructed. These zones are: the N-E Cairo, S-W Cairo, Beni Swief, S-E Assuit and Aswan area. In the frame of Tensor program the improved Right Dihedron Method by Delvaux and Sperner (2003) was applied to evaluate the orientation of the principle stress axes and the shape of the stress tensor for the proposed seismic zones. It showed the heterogeneous stress regime around the Nile valley. In the N-E Cairo seismic zone the stress regime is extensional, but in the S-W Cairo seismic source, the stress regime is different, where the strike slip component is present. Beni Swief Seismic zone, in the North Eastern part, was characterized by extensional stress regime. Around the Nile Valley, In the Middle Egypt, the stress regime is pure strike slip, while in the Aswan a...
ABSTRACT The large tsunamigenic earthquake that shook the eastern Mediterranean in the second hal... more ABSTRACT The large tsunamigenic earthquake that shook the eastern Mediterranean in the second half of the 4th century AD with a magnitude which is only roughly estimated as being of at least 8 has been considered as one of the largest earthquakes ever reported in the Mediterranean Sea. A general consensus exists that it occurred on 21 July 365 in the western Hellenic Arc causing a co-seismic uplift in western Crete up to c. 9 m. However, the rupture zone is not well constrained so far. From historical and geological documentation it has been supported that the tsunami inundated not only in near-field but also in remote coastal sites in the entire basin of the Mediterranean. We reexamine critically the available documentary sources and geological information, create an inventory of the most credible coastal sites to have inundated and conclude that the tsunami propagation zone very likely was less than what was considered so far. From dislocation modeling scenarios we reproduce several candidate seismic sources and simulate numerically the resulting tsunami. Then, calculated tsunami wave heights and runups are compared with the observed ones in credible coastal sites to determine the most candidate rupture zone of the earthquake. Implications of such a determination for the tsunami hazard assessment particularly for the West Hellenic Arc as well as for Alexandria is of great interest since there is the most reliable description of tsunami impact. Finally, by extending probabilistic hazard assessment from earthquakes to tsunamis we perform tsunami hazard assessment for Alexandria for a future 365-type tsunami by employing a combination of probability evaluation of earthquakes in the tectonic segment that generated the 365 event and of the tsunami numerical simulation.
The objective of this study is to evaluate the seismic hazard at the northwestern Egypt using the... more The objective of this study is to evaluate the seismic hazard at the northwestern Egypt using the probabilistic seismic hazard assessment approach. The Probabilistic approach was carried out based on a recent data set to take into account the historic seismicity and updated instrumental seismicity. A homogenous earthquake catalogue was compiled and a proposed seismic sources model was presented. The doubly-truncated exponential model was adopted for calculations of the recurrence parameters. Ground-motion prediction equations that recently recommended by experts and developed based upon earthquake data obtained from tectonic environments similar to those in and around the studied area were weighted and used for assessment of seismic hazard in the frame of logic tree approach. Considering a grid of 0.2 Â 0.2 covering the study area, seismic hazard curves for every node were calculated. Hazard maps at bedrock conditions were produced for peak ground acceleration, in addition to six spectral periods (0.1, 0.2, 0.3, 1.0, 2.0 and 3.0 s) for return periods of 72, 475 and 2475 years. The unified hazard spectra of two selected rock sites at Alexandria and Mersa Matruh Cities were provided. Finally, the hazard curves were de-aggregated to determine the sources that contribute most of hazard level of 10% probability of exceedance in 50 years for the mentioned selected sites.
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Papers by Mohamed Ezzelarab