دخول أعضاء

04/04/2020


جامعة النجاح الوطنية
منسق المشروع

www.najah.edu

 الصفحة الرئيسية >

Data Resources Category
Data Resources Category Scientific Paper
Research Title Crustal shear velocity structure across the Dead Sea Transform from two-dimensional modelling of DESERT project explosion seismic data

Published by (sources)

Geophysical Journal International, 160, 3, 910-924

Carried out by (authors)

Ayman Mohsen
Issue Year 2005
Abstract 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 (Vp/Vs= 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 (Vp/Vs= 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 (Vp/Vs= 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 (Vp/Vs= 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.
 

جميع الحقوق محفوظة لمشروع ساسبارم 2013
مركز التخطيط الحضري والحد من مخاطر الكوارث