Magnetic and Geo-electrical Geophysical Techniques for Subsurface Delineation and Groundwater Assessment in Ras Matarma, Sinai

Groundwater constitutes the main source of the freshwater in Ras-Matarma, Sinai, which necessitates optimized management of it. In this context, geophysical ground magnetic, Schlumberger resistivity inversion, remote sensing (RS), geographic information system (GIS), and pumping tests were conducted. The magnetic survey comprised 56 profiles, whereas, Schlumberger resistivity survey were 27 VES. GIS and RS were implemented for watershed analyses in the area. Interpretation of the magnetic data separated significantly the shallow and deep structures with depths ranged from 300 to 1400 m. Qualitative and quantitative modelling of the inverted resistivity data demarcated effectively the fresh aquifer with true resistivity and thickness ranged from 22 to 210 ohm.m and 2 to 80 m, respectively. GIS aggregated all the aforementioned results along with electric and hydraulic parameters of the fresh aquifer.

Tectonic Environments of Strong Earthquakes in the North China Region

The North China Seismic Region is not a typical intraplate seismic region. Not only does it show a pervasive neotectonic influence of global plate geodynamics, but it also displays an atypical seismic activity rate, especially for strong earthquakes, for a region far from plate boundaries. It is obvious that the seismicity is related to the active seismotectonics and geodynamics of the deforming interior of a continental plate. The features of the seismotectonic zones and the tectonic setting of magnitude 6.0 or greater earthquakes in the region are discussed here. We conclude that strong earthquakes occur mainly in places where NE-trending main and NW-trending auxiliary tectonic zones intersect. Three types of mechanisms are suggested which differ according to the characteristics of different seismotectonic zones and which relate to different shallow and deep structures. These observed types of strong earthquakes in North China may represent the main categories of continental intraplate seismicity.