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The geothermal resources of Saudi Arabia are mainly located in the southwestern parts associated with a series of volcanic rocks and ridges. Jizan area is considered as one of the most promising geothermal targets which are characterized by the presence of a number of structural related hot springs with a surface temperature range of 46 to 79°C at the surface. This work mainly aims to throw light on the possible potentiality of these resources at Jizan area, through analyzing the available satellite images and interpreting the geothermometer data. A number of Landsat and Spot satellite images, which cover the study area, are analyzed. The drainage pattern, digital elevation model and the prevailing structural elements are all interpreted. Three main thermal anomalies are recognized (Al Ardah, Al Khouba and Bani Malik), and more closely located to the east, away from the coastal plain in areas of high and complicated topographic nature, and originating from hard crystalline rocks. The general slope decreases notably westward from 45° in the high hill areas to 1° near the sea coast. The prevailing drainage patterns are mainly denderitic, running seaward and associated with up to four seaward-oriented coastal basins. A geo-thermometer based study (Silica, Na, K and Mg) was performed by analyzing the different water samples collected from the different studied hot springs and adjacent water wells to determine the subsurface formation temperature, heat flow and water type. Much higher thermal regimes are recognized in the localities occupied by the hot springs as compared with other surrounding areas. Maximum values up to 152°C and 210 mW/M 2 are recorded for the subsurface temperature and heat flow respectively. The studied hot springs are promised and needs to be further investigated and accessed by additional geophysical methodologies.

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The Pamir and Hindu Kush are examples of a puzzling collision system where a complex junction of colliding lithospheric plates coexists with intermediate depth seismicity at 300 km. In this study, we constructed a new tomography model using travel time data from local events recorded by the TIPAGE (Tien Shan – Pamir Geodynamic program) network. In addition to the P- and S-wave velocities down to 200 km, we derived the azimuthal anisotropy. The velocity anomalies were consistent with the results of previous studies. In the crust, the velocity structure and anisotropy directions were mainly oriented along major suture zones. At depths of 80–120 km, a narrow low-velocity anomaly coinciding with the distribution of deep seismicity was interpreted as a trace of entrained crustal material by the dipping lithosphere. The anisotropy directions at these depths were mainly oriented northwest–southeast and were interpreted as indicating the direction of the motion of colliding plates. The difference in the magnitude of anisotropy south and north of the Pamir seismic zone suggests that the lithosphere coming from the south possesses less anisotropy than that of the Asian plate. The local tomography model was supplemented by previously computed regional tomography that expanded the area both laterally and axially. Beneath the Pamir, both continental plates coming from the north and south form a drop-shaped anomaly that will possibly delaminate in time. Beneath the Hindu Kush, we could clearly trace a continuous almost vertical subduction of the Katawaz block from the south. Thus, the continental collision beneath the Pamir and subduction beneath the Hindu Kush are separate processes with different rates and directions of plate movement.

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