khaled omar

Abstract Seismo-magnetic investigation can play an important role in the investigation of various phenomena connected with earthquakes. The main target of this study is to investigate the magnetic variations associated with the swarm seismic activity along the fault structures in Gulf of Aqaba. Instrumental seismicity of Aqaba Gulf and magnetic observations were collected and analyzed during the period of 1982–2009. Seismo-magnetic effects were investigated through comparisons of magnetic and earthquake activity for long term and diurnal variations during the observed period. The distribution of these changes exhibited a distinguishing pattern, which could be related to the seismicity in certain periods of high swarm seismic activity and/or strong earthquakes. The seismo-magnetic effects were increased slowly and gradually with swarms but they were increased abruptly with strong earthquakes. Physically, this difference in Sq manners between swarm and strong earthquakes could be interpreted in view of stress force due to earthquakes and gaps along the segments fault of Aqaba Gulf which controlled the rocks containing highly magnetic constituents. The authors concluded that the seismo-magnetic effects were appreciated as a dependent element on the seismic swarm and large earthquake variables. Each of swarm and strong earthquakes has a specific manner of seismo-magnetic effect. This can be used as a powerful tool as a short-term prediction for anticipating strong earthquakes along the segmented fault of Aqaba Gulf.

The monitoring of network measures, such as degree centrality, betweenness centrality, and clustering coefficient is performed, aiming to identify the periods that the earthquake network has distinct evolution before the main shock on June 24, 2015 in the area of Egypt. As nodes the 42 square cells that constitute a normal lattice imbricate on the investigation region are considered and the connections are drawn whenever earthquake succession is predestined between the node areas of seismic activity of the corresponding nodes. The data are possessed from a seismic catalog including crustal earthquakes (focal depth less than 50 km) of magnitude that occurred in the area of Egypt during the period of 1998-2015. The earthquake network is created on sliding windows of 90 days and then the values of 9 network measures on each sliding window are computed before the main shock on June 24, 2015. The investigation of network measures revealed that more of the network measures values exhibit an abrupt jump just before the main shock occurrence.

The Gulf of Aqaba is situated along the southern part of the Dead Sea Rift Area transform (DST), 1000 km (620 miles), the boundary between the African plate and the Arabian plate. It is situated toward the east of the Sinai landmass and west of Saudi Arabia. It is one of the joints interfacing the Asian and African landmasses. The Gulf expands 180 km from Eilat and Aqaba and joins the Red Sea in the Strait of Tiran, with the most extensive purpose of 28 km. On November 22, 1995, the biggest seismic tremor estimating 7.0 degrees happened along parts of the dead left line in the Gulf of Aqaba close to the port of Nuweiba in Egypt. This tremor made extraordinary harm Egypt and neighboring nations. Consequently, a few point by point investigations of seismology and geophysics have been led in the Gulf of Aqaba. In the territory researched, the vast majority of the ongoing seismic action revolved around the Gulf of Aqaba is portrayed by the contribution of moderate central quakes, an immediate aftereffect of the relative development between the plates of Africa, Sinai and the Arabian Peninsula. Seismic Energy along the Gulf of Aqaba locale is assessed utilizing a brief period (50 tests for every second) executed by the Egyptian National Seismic Network amid the period 1998‒2017. The connection between the dispatch and greatness of quakes in the Gulf of Aqaba demonstrated that the vast majority of the seismic Energy discharge originates from the biggest occasions and is packed in the inside, while it is moderately low in the southern and northern parts of the Gulf.

ABSTRACT 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 mixed in their electrical properties. The sites of the detected faults are identifying with the seismic activity of the area.

ABSTRACT Greater Cairo and the Nile Delta are considered very important, high-density population areas. The subject of the research work is dealing with recent crustal movements and its relation to seismicity and tectonics setting. A Global Positioning System (GPS) network consisting of 11 benchmarks covering Greater Cairo and the southern part of the Nile Delta was established in 1996. Different campaigns surveyed the network. In this study, we used ten measurements collected during the period from 2004 to 2010. The data were processed using Bernese 5.0 software to derive velocity vectors and principal components of crustal strains. The horizontal velocity varies in average between 3 and 6 mm per year across the network. Rate of the accumulated strains in the southern part of Greater Cairo varies from low to moderate. The low strain rates and low level of earthquakes occurrence in the present interval in the Nile Delta area indicated that the rate of the deformation in this area is small. The result from coupling GPS and seismic data indicates that the southern part of the area is seismo-active area when compared with the other parts in the network areas. The paper gives information about the present state of the recent crustal movements within Greater Cairo area to understand the geodynamics of that area. This study is an attempt to build a basis for further development of seismic catastrophic risk management models to reduce a risk of large catastrophic losses within the important area.

On the 16th June, 2020, a moderate earthquake (Mw = 5.2) hit the Northern Red Sea region, Egypt, that was felt throughout the Hurghada and Sharm El-Sheikh cities and the surrounding areas without any damages. The thermal anomaly before the earthquakes was widely studied with satellite data, such as NOAA/AVHRR and MODIS. The case study aims to monitor and demonstrate the possibility of any variation of the thermal anomaly of sea surface temperature (SST) before and after the 16th June 2020 earthquake and to correlate the results with the previous heat flow study (deep thermal action). The Daytime/Nighttime (SST) data are retrieved from the OBPG serves as a Distributed Active Archive Center (OB. DAAC). The outputs indicated a thermal anomaly on the June 12th, 2020 a few days before the earthquake, covered a large area around the epicenter 60 km impact area, and reached a high value on the 15th June 2020, one day before the earthquake. For the deep thermal action of the entire crust, t...

ABSTRACT Africa displays a variety of continental margin structures, tectonics and sedimentary records. The northern Egyptian continental margin represents the NE portion of the North African passive continental margin. Economically, this region is of great importance as a very rich and productive hydrocarbon zone in Egypt. Moreover, it is characterized by remarkable tectonic setting accompanied by active tectonic processes from the old Tethys to recent Mediterranean. In this article, seismicity of the northern Egyptian continental margin has been re-evaluated for more than 100-years and the source parameters of three recent earthquakes (October 2012, January 2013 and July 2013) have been estimated. Moment tensor inversions of 19th October 2012 and 17th January 2013 earthquakes reveal normal faulting mechanism with strike–slip component having seismic moment of 3.5E16 N m and 4.3E15 N m respectively. The operation of the Egyptian National Seismic Network (ENSN) since the end of 1997 has significantly enhanced the old picture of earthquake activity across northern Egyptian continental margin whereas; the record-ability (annual rate) has changed from 2-events/year to 54-event/year before and after ENSN respectively. The spatial distribution of earthquakes foci indicated that the activity tends to cluster at three zones: Mediterranean Ridge (MR), Nile Cone (NC) and Eratosthenes Seamount (ERS). However, two seismic gaps are reported along Levant Basin (LEV) and Herodotus Basin (HER).

ABSTRACT The present day tectonic deformation within Egypt is related to the regional tectonic forces of the surrounding plate boundaries including the African–Eurasian plate margin, the Red Sea plate margin and the Levant transform fault in addition to the local tectonics of Egypt. Based on the spatial distribution of earthquake epicenters in Egypt, the most seismically active areas are located in the Northern Red Sea, Gulf of Suez, Gulf of Aqaba and Mediterranean coastal zone. On 30 January 2012, a moderate earthquake of local magnitude ML 4.6 struck the northeast part of Egypt, at the entrance of Gulf of Suez. This event was felt in many areas surrounding the epicenter with low damage recorded. To understand the mechanism and the reflected irregularity of the evolved stress field concerning the Gulf of Suez area, calculation of source parameters and source mechanisms of this event are necessary. Moment tensor inversion is used to retrieve the fault plain solutions and the seismic moment by using waveforms recorded by the Egyptian National Seismic Network. The fit between observed and synthetic seismograms was computed for an elastic layered media and minimized using a least squares algorithm. The derived source mechanism indicates normal faulting along NNW–SSE trending faults, in agreement with the rifting of the northern Red Sea in its northern branches (Gulf of Suez and Gulf of Aqaba). The source parameters are estimated and the derived corner frequency f o for the P-wave spectra shows a value of 3.00 Hz. The seismic moment M o is 1.278 × 1023 Nm, the fault length r is 0.8 km, the average displacement D 0 is 0.023 m, and the value of the stress drop Δσ is 1.10 MPa. The source mechanism and source parameters imply the continuous activity of the Red Sea rift system at the Gulf of Suez opening.