Open AccessCrustal shear velocity structure across the Dead Sea Transform from two‐dimensional modelling of DESERT project explosion seismic data
Author(s) -
Mechie J.,
AbuAyyash K.,
BenAvraham Z.,
ElKelani R.,
Mohsen A.,
Rümpker G.,
Saul J.,
Weber M.
Publication year - 2005
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2005.02526.x
Subject(s) - geology , seismology , crust , mantle (geology) , seismic refraction , shear velocity , geophysics , meteorology , physics , turbulence
SUMMARY An analysis of the shear ( S ) waves recorded during the wide‐angle reflection/refraction (WRR) experiment as part of the DESERT project crossing the Dead Sea Transform (DST) reveals average crustal S ‐wave velocities of 3.3–3.5 km s −1 beneath the WRR profile. Together with average crustal P ‐wave velocities of 5.8–6.1 km s −1 from an already published study this provides average crustal Poisson's ratios of 0.26–0.27 ( V p / V s = 1.76–1.78) below the profile. The top two layers consisting predominantly of sedimentary rocks have S ‐wave velocities of 1.8–2.7 km s −1 and Poisson's ratios of 0.25–0.31 ( V p / V s = 1.73–1.91) . Beneath these two layers the seismic basement has average S ‐wave velocities of around 3.6 km s −1 east of the DST and about 3.7 km s −1 west of the DST and Poisson's ratios of 0.24–0.25 ( V p / V s = 1.71–1.73) . The lower crust has an average S ‐wave velocity of about 3.75 km s −1 and an average Poisson's ratio of around 0.27 ( V p / V s = 1.78) . No Sn phase refracted through the uppermost mantle was observed. The results provide for the first time information from controlled source data on the crustal S ‐wave velocity structure for the region west of the DST in Israel and Palestine and agree with earlier results for the region east of the DST in the Jordanian highlands. A shear wave splitting study using SKS waves has found evidence for crustal anisotropy beneath the WRR profile while a receiver function study has found evidence for a lower crustal, high S ‐wave velocity layer east of the DST below the profile. Although no evidence was found in the S ‐wave data for either feature, the S ‐wave data are not incompatible with crustal anisotropy being present as the WRR profile only lies 30° off the proposed symmetry axis of the anisotropy where the difference in the two S ‐wave velocities is still very small. In the case of the lower crustal, high S ‐wave velocity layer, if the velocity change at the top of this layer comprises a small first‐order discontinuity underlain by a 2 km thick transition zone, instead of just a large first‐order discontinuity, then both the receiver function data and the WRR data presented here can be satisfied. Finally, the S ‐wave velocities and Poisson's ratios which have been derived in this study are typical of continental crust and do not require extensional processes to explain them.