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Intermediate depth earthquakes beneath the India‐Tibet Collision Zone
Author(s) -
Zhu Lupei,
Helmberger Donald V.
Publication year - 1996
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/96gl00385
Subject(s) - geology , seismology , crust , collision zone , lithosphere , fault plane , thrust fault , mantle (geology) , fibrous joint , collision , stress field , main central thrust , slip (aerodynamics) , focal mechanism , induced seismicity , fault (geology) , tectonics , geophysics , computer science , medicine , physics , computer security , anatomy , finite element method , thermodynamics
We report on three intermediate depth earthquakes in the India‐Tibet collision zone, two under the Himalayan Thrust Belt (HTB) and one beneath the Indus Zangbo suture. The m b magnitudes of these three events are from 4.3 to 4.9, and are too small to be well located by conventional means. However, from modeling their broadband waveforms recorded at near‐regional distances on a temporary PASSCAL array, we can confidently confine the sources to be below the crust, between 70 and 80 km deep. The existence of these intermediate depth earthquakes in this area suggests relatively low temperatures in the mantle lithosphere. The two events under the HTB display strike‐slip mechanisms with some normal faulting component; this is quite different from the shallow thrust events typical of the same area. The principal P and T axes of all 3 fault plane solutions show roughly NS compression and EW extension, consistent with a regional stress field produced by the indenting of the India continent.