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Journal of Seismology - By utilizing teleseismic data, the P-wave receiver functions (RFs) have been computed for 20 broadband seismic station deployed in Harrat Khaybar and Ithnayn, in the Arabian... 相似文献
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The source process and parameters for a moderate earthquake of magnitude Ml 4.1 that occurred on the Kalabsha fault at the Aswan area are analyzed. The derived focal mechanisms of this event and other two aftershocks using polarities of P, SV, and SH waves show strike-slip fault with minor vertical movement of normal type. The solutions give two nodal planes trending ENE–WSW and NNW–SSE in close agreement with the surface traces of the faults crossing the area. The movement is right lateral along the first plane while left lateral along the second one. The rupture process characterization of this event has been investigated by using the empirical Green’s function deconvolution method. By inversion only for the P wave part of the records of these three events (main and other two aftershocks), the source time function for the master events and the azimuthally variations in the (RSTF) pulse amplitude are retrieved for estimating the rupture directivities. The estimated rupture direction is combined with the P-wave focal mechanisms for the three events to identify the fault plane solution for these earthquakes. Based on the width, amplitudes, and numbers of the isolated source time functions, a complex bi-lateral rupture of the studied earthquake is delineated. The source parameters of the master event is calculated and the derived corner frequencies f o for P-wave spectra show a value of 6.6 Hz; the seismic moment (M o ) is 4.2?×?1022 Nm; the average displacement (U) is 0.5 m; fault radius (r) 40 m; the average value of the stress drops (Δσ) is 0.6 Mpa, and the moment magnitude (M w ) is 4.4. 相似文献
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The Global Positioning System (GPS) is considered as one of the most powerful tools that are used in geodetic works. It is increasingly considered as an alternative tool for conventional surveying techniques. The goal of this research paper is to produce a methodology for generating topographic contour maps using the post-processed kinematic differential GPS technique (PPK-GPS). The performance of this technique is assessed by comparing it with the traditional spirit-leveling technique taking into consideration the accuracy, time, and cost. The study area is located along the Mediterranean coast in the Rosetta area of the middle Delta in Egypt with a total area of about 39 km2. The field work includes 14 control points and about 50,000 PPK observations. In addition, 20 check cross sections that extend along the coastal line from Rosetta to El Burullus cities were observed using both spirit-leveling and GPS-PPK techniques. The results of the comparison indicate that the PPK-GPS technique can be used instead of spirit leveling in producing a topographic contour map with an accuracy of about 20 cm in orthometric height. We find that the PPK-GPS technique reduces the estimated time of leveling works in our study area by about 70%. 相似文献
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Hosny M. Ezz El Deen Ahmed N. El Sayed Mostafa S. M. Barseem 《Arabian Journal of Geosciences》2014,7(6):2151-2163
The present study aims to explain some hydrogeological problems that are related to geological setting in two wadis: El Kallabiyyah and As Sabil East Esna. For this purpose, land magnetic, vertical electrical soundings, and two-dimensional electrical resistivity imaging profiles were measured. The lithological succession comprises Upper Cretaceous to Quaternary deposits that rest on a Precambrian basement rock. The results of the interpretation of the land magnetic measurements in wadi El Kallabiyyah represent the depth to the basement rock which ranges from 260 to 660 m and increases towards the northeast trend, but in wadi As Sabil, there is a large basin at the center of the wadi with the recorded depth to the basement reaching 1,300 m due to the effect of two normal faults (F1 and F2). The results of the interpretation of the vertical electrical sounding and two-dimensional imaging confirmed the presence of these faults in wadi As Sabil. The results of the geoelectrical measurements in wadi El Kallabiyyah represented the water-bearing layer at the third unit that consists of sands, gravels, boulders, and clays. The presence of clay will affect the potentiality of a drilled well. For wadi As Sabil, the results of geoelectrical measurements led to the lower part of the second unit which acts as a water-bearing layer that consists of sands, boulders, gravels, and clays. It can be concluded that the best site for drilling wells in wadi El Kallabiyyah is at vertical electrical sounding no.5 with a total depth of not less than 230 m. In wadi As Sabil, the drilled wells must be concentrated at the center and the downstream. 相似文献
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