Seismic studies of the Arava Fault, Dead Sea Rift Transform, Jordan

With a length of more than 1100 km the Dead Sea Rift Transform (DST) comprises one of the largest transform systems on Earth. During the last 18 Ma it experienced a left-lateral motion of about 100 km, and todays activity is indicated by recent seismicity. As part of the project DESERT 2000 we conducted an active seismic experiment in and around one of the major faults of the DST, the Arava Fault, complementing data from wide-angle refraction, near-vertical reflection, and passive seismological experiments. Main goal of this experiment is the investigation of properties and 3-D geometry of the fault by the observation of fault reflections, converted waves, and fault zone guided waves. We deployed 270 geophone channels on three 10 km lines crossing the Arava Fault roughly W-E and 9 mini arrays of 10 stations equipped with three-component seismometers. 53 chemical explosions within shot clusters around the study area were used as seismic sources. We see clear secondary arrivals which can be interpreted as reflections of the steeply dipping Arava Fault, and the seismic data reveal a rather complex velocity structure west and east of the fault. The mini arrays running continuously for a period of 7 days recorded various regional and teleseismic events and two small-magnitude local earthquakes in the direct vicinity of the fault. We present preliminary results of our studies.