Sayed A. Dahy

National Research Institute of Astronomy and Geophysics

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Gaber H. Hassib

National Research Institute of Astronomy and Geophysics

E. M. El-Amin

National Research Institute of Astronomy and Geophysics

Mohamed Ebraheem

New Valley University

Khaled Omar

National Research Institute of Astronomy and Geophysics

Mohammed A. Mohammed

Bridge University

Awad Hassoup

National Research Institute of Astronomy and Geophysics

Anwar H. Radwan

National Research Institute of Astronomy and Geophysics

Haggag H. Mohamed

National Research Institute of Astronomy and Geophysics

Haggag Hamed

National Research Institute of Astronomy and Geophysics

Ali Rayan

National Research Institute of Astronomy and Geophysics

Cooperative Institutions

National Research Institute of Astronomy and Geophysics

Bridge University

Aswan University

King Saud University

Sohag University

Al-Nisour University College

University of Baghdad

Mustansiriyah University

Nahrain University

University of Mosul

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Seismic Activity and Energy Release of Earthquakes along the Gulf of Aqaba, Egypt

Geotectonics (2019)

Khaled Omar E. M. El-Amin Sayed A. Dahy Mohamed Ebraheem

Seismic energy

10.1134/s0016852119060116

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Citations (1)

Study of the Relationship between Recently Induced Earthquakes and Water Level at the Northwestern Side of Lake Nasser in Aswan Region, Egypt

Geotectonics (2019)

Khaled Omar E. M. El-Amin Sayed A. Dahy Mohamed Ebraheem

10.1134/s0016852119020067

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Citations (3)

Discrimination between natural earthquakes and nuclear explosions using the Aswan Seismic Network

Annals of Geophysics (1998)

R.M. Kebeasy Aziza I. Hussein Sayed A. Dahy

There are many seismological differences between earthquake and nuclear explosions, but not all of them are observable at large distances or are applicable to every earthquake and explosion. Several discriminations have been checked using the Aswan Seismic Network (ASN) data. Data of 66 earthquakes and 42 presumed underground explosions which occurred in different regions of China, the U.S.S.R., India, Iran, Turkey and recorded at ASN were collected. All data were selected from the NEIC catalogue and EDR reports. It was found that mb: Msas well as mb(1 Hz): mb (2 Hz) work well for events with mb larger than 4.0 from data observed at ASN and obtained from the NEIC catalogue.

10.4401/ag-4324

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Citations (10)

Detecting and Identifying Seismic Events Using the Egyptian National Seismic Network

Sayed A. Dahy Gaber H. Hassib

The detection and monitoring of underground nuclear explosions has been discussed for over 40 years in connection with verification of the comprehensive test ban treaties and identifying of seismic events is also one of the basic ways to learn about nuclear weapons development in different countries. Nuclear explosions have a number of differences from other events that lead to differences in their seismic signatures. The present study described the different kinds of seismic sources and the basis for solving the identification problem. Large natural or artificial events, with magnitudes greater than 4.8 are detected by Egyptian National Seismic Network (ENSN) and the detection capability of teleseismic events for distance range between 25° to 35° is clearly low at body wave magnitude less than 5.0. A number of identification methods have evolved. These can be identified by well-established discrimination techniques such spectral analysis of body waves and also from magnitude residuals versus body wave magnitude plots. From this study, we concluded that, explosions are characterized by more high-frequency energy than earthquakes and discrimination between teleseismic earthquakes and nuclear explosions could be achieved at high magnitude range, but for smaller events, it can be very difficult to detect and to discriminate between them. Also, separation between natural earthquakes and nuclear explosions is observed clearly using the relation between magnitude residuals with body wave magnitudes.

Nuclear explosion

Nuclear test

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Seismic Active Zones and Mechanism of Earthquakes in Northern Egypt

World Academy of Science, Engineering and Technology, International Journal of Civil and Environmental Engineering (2012)

Sayed A. Dahy

Northern Egypt is known to be seismically active from the past several thousand years, based on the historical records and documents of eyewitnesses on one- hand and instrumental records on the other hand. Instrumental, historical and pre- historical seismicity data indicated that large destructive earthquakes have occurred quite frequently in the investigated area. The interaction of the African, Arabian, Eurasian plates and Sinai sub-plate is the main factor behind the seismicity of northern part of Egypt. All earthquakes occur at shallow depth and are concentrated at four seismic zones, these zones including the Gulfs of Suez and Aqaba, around the entrance of the Gulf of Suez and the fourth one is located at the south- west of great Cairo (Dahshour area). The seismicity map of the previous zones shows that the activity is coincide with the major tectonic trends of the Suez rift, Aqaba rift with their connection with the great rift system of the Red Sea and Gulf of Suez- Cairo- Alexandria trend. On the other hand, the focal mechanisms of some earthquakes occurred inside the studied area and having small to moderate size show a variety of patterns. The most predominant type is normal faulting.

Focal mechanism

Rift valley

East African Rift

Rift zone

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Citations (8)

Spectral Discrimination Between Quarry Blasts and Microearthquakes in Southern Egypt

Sayed A. Dahy Gaber H. Hassib

Several discrimination methods are examined for identifying earthquakes as events distinct from possible underground explosions. In the present work , the most promising short- period discriminants, spectral analysis and logarithmic values of P- wave to S- wave phase- amplitude ratios, for a data set from southern Egypt was evaluated. Data consist of 17 quarry blasts and 22 earthquakes, ranging from magnitude 1.9 to 3.7, recorded at three seismic stations operated by Aswan Earthquake Research Center. In contrast with much previous discrimination work in different regions, the common stations and paths for all the events in this study allow the discriminants to be evaluated without applying propagation corrections and differences between events can be ascribed to very near source effects. The source effects was found to have the most influence on the discriminants in this study the source properties of quarry blasts; the daynamic characteristics of their waves, amplitudes, periods and waveform in comparison with the same microearthquakes characteristics have been studied. In conclusion, comparison between two seismic sources suggests that the discrimination between natural earthquakes and quarry blasts at regional distance may be possible and the differences between them turned out most clearly from their spectra.

Spectral Analysis

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Citations (15)

Erratum to: Seismotectonic Setting of the Egyptian Western Desert

Geotectonics (2023)

Khaled Omar Sayed A. Dahy Mohammed A. Mohammed E. M. El-Amin Mohamed Ebraheem

An Erratum to this paper has been published: https://doi.org/10.1134/S0016852123100011

Desert (philosophy)

10.1134/s0016852123100011

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Seismotectonic Setting of the Egyptian Western Desert

Geotectonics (2023)

Khaled Omar Sayed A. Dahy Mohammed A. Mohammed E. M. El-Amin Mohamed Ebraheem

Microearthquake

Desert (philosophy)

Seismometer

Seismotectonics

Moment magnitude scale

10.1134/s0016852123040106

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Monitoring of recent crustal movements around Cairo by repeated gravity and geodetic observations

DOAJ (DOAJ: Directory of Open Access Journals) (2010)

E. Issawy Anwar H. Radwan Sayed A. Dahy Ali Rayan

The mass distribution and density inhomogeneities are one of the main factorsaffecting Earth’s dynamics. The temporal gravity variations were used to understand thesurface tectonics and geodynamic modeling after the occurrence of an earthquake of 1992.The gravity field changes have been used for monitoring recent crustal movements in thearea around Cairo and Southern part of Delta, Egypt. More than five successive gravitymeasurement campaigns were performed in parallel with the geodetic technique (GPS).The gravity changes were determined and correlated with seismic activity for all periodsof observations. It was found that there is a certain relation shown by increasing ofgravity values before the main seismic activity. As an example, a relatively considerableincrease of gravity values was noticed for the network between the epochs of 2000 and2004. Otherwise, the temporal gravity variations exhibited a considerable decrease ingravity values between the two campaigns of 2004 and 2007 for the same stations. Thisbehavior could be explained by compressive deformation and strain buildup stage beforethe Southwestern Cairo earthquake (July 31, 2005 with magnitude of 4.3) and the stressrelease stage occurred after the main-shock. In addition, the results of geodetic measurementsof the network around Cairo after five campaigns showed that the estimatedhorizontal velocities for almost of points are 5.5 mm/year in approximately NW direction.

Gravimeter

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Identification of local seismicity observed south of Aswan City — Egypt

Acta Geodaetica et Geophysica Hungarica (2008)

Sayed A. Dahy Gaber H. Hassib Abdel-Monem Mohamed Awad Hassoup

Suddenly, Aswan Seismic Network detected and observed a number of events beside Aswan city. The magnitude of these events ranged from 0.9 to 2.6. These events were considered very important events because they were located not far from the Aswan High Dam. The main purpose of this work is to investigate and identification of these events using different seismic methods. Small earthquakes and explosions have the same flat and displacement spectrum for short-period P waves and discrimination of small events rests on detection and location. The final result appears that the source of these events is not an artificial type.

Identification

Microseism

10.1556/ageod.43.2008.1.7

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