Detecting and mapping recent faults with a ground penetrating radar in the alluvial fans of the Arava valley, Israel

Ground Penetrating Radar (GPR) field experiments were conducted to detect recent faults that may be connected to the Dead-Sea Rift, on several all uvial fans in the southern Arava Valley, Israel. The existence of fault-scarps and lineaments interpreted as surficial faults there, indicated the Late Pleistocene and Holocene seismic activity of the rift. High resolution GPR profiles were carried out to map the shallow stratigraphy of the alluvial deposits and to detect subsurface recent faults. The GPR experiments were a part of integrated neotectonic research, which combines geophysical and geomorphological complementary methodsto investigate recent faulting events. During the study we used GPR and trench excavations to detect and study faults which rapture the surface, and faults with no visible surficial expression. The profiles that were conducted to cross the faults perpendicularly have produced reflections that were not sufficiently different from reflections of stratigraphic discontinuities that are common in the alluvial fans. On the other hand, a dramatic indication interpreted as a fault has been obtained in the profiles that were conducted along a wide faulted zone discontinuity, and along a strike-line of a fault, which is significantly wider then other lateral discontinuities. Consequent to locating a suspected faulted zone, high-resolution GPRmapping of its typical stratigraphy can be made. In spite of the complex stratigraphy of the alluvial fans, which produces abundance of pitfall reflection anomalies, we introduce a powerful way to identify the faults with GPR. The results of the GPRmapping can help focusing the trench excavations that are essential for understanding the details ofthe paleo seismic faulting events. Prospecting offaulted zones with GPR can reduce the excavation activities to a minimum, save time, effort and damage to the landscape.