Publication Date:
2020-02-12
Description:
During the INDEPTH IV controlled-source experiment in June 2007, Sg arrivals were well recorded by the 20 broadband and 29 short-period three-component seismographs, from GIPP, Germany and SEIS-UK, deployed at 5-6 km station spacing along the 270 km long profile across the Kunlun mountains in NE Tibet. Based on these arrivals, Sg arrivals could also be safely identified on the vertical-component geophones attached to the 949 IRIS-PASSCAL Texans, spaced at 100-600 m along the profile. A tomographic inversion of the Sg arrivals recorded by these 998 instruments from 5 large shots (1000-2000 kg) and 100 small shots (80 kg) reveals the S-velocity structure of the upper crust down to about 10 km depth beneath the profile. The major lateral variation in upper crustal S-velocities along the profile is from lower velocities beneath the Qaidam basin in the north to higher velocities beneath NE Tibet in the south. Beneath NE Tibet, there are also lateral variations with lower S-velocities beneath the valleys (basins) along which the North Kunlun and South Kunlun Faults run and higher velocities in the mountainous regions between and to the north and south, where older rocks are generally exposed at the surface. From the S-velocity model, there is no evidence within the upper crust for major overthrusting of NE Tibet over the Qaidam basin.
Keywords:
550 - Earth sciences
Type:
info:eu-repo/semantics/conferenceObject
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