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Geometry of the Main Himalayan Thrust and Moho beneath Satluj valley, northwest Himalaya: Constraints from receiver function analysis
Author(s) -
Hazarika Devajit,
Wadhawan Monika,
Paul Arpita,
Kumar Naresh,
Borah Kajaljyoti
Publication year - 2017
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2016jb013783
Subject(s) - geology , foreland basin , receiver function , seismology , crust , main central thrust , structural basin , ridge , thrust , lithosphere , geomorphology , tectonics , paleontology , physics , thermodynamics
Crustal configuration beneath the Satluj valley region of the northwest Himalaya has been studied with the help of receiver function analysis of teleseismic earthquakes recorded by 18 broadband seismological stations. These stations were located on diverse geotectonic units from the Himalayan foreland basin in the south to the Tethyan Himalaya (TH) in the north. A gentle north dipping structure of the Main Himalayan Thrust (MHT) is imaged between the Sub and Higher Himalaya in contrast to the reported ramp structure of the MHT beneath the Garhwal and Nepal Himalaya. The ramp structure is, however, identified further north, beyond the South Tibetan Detachment in Satluj valley. The depth of the MHT varies from ~16 to 27 km across the Sub, Lesser, and Higher Himalaya, and it increases to ~38 km beneath the TH forming a ramp. This is significantly a different structure of the MHT beneath the Satluj valley, which is attributed to the effect of underthrusting Delhi‐Hardwar Ridge, a transverse structure to the Himalayan arc. Conspicuously, no strong or large earthquake is observed during 1964–2015 in this segment of the Himalayan Seismic Belt. The RF modeling, on the other hand, shows ~44 km crustal thickness beneath the Himalayan Frontal Thrust (HFT), and it gradually increases to ~62 km beneath the TH. Low shear wave velocity (~0.8–1.8 km s −1 ) is observed in the uppermost 3–4 km of the crust beneath the stations near the HFT, which may be the effect of the sedimentary column of the Indo‐Gangetic Plain.