On the paleoseismic evidence of the 1803 earthquake rupture (or lack of it) along the frontal thrust of the Kumaun Himalaya

Rajendran, C P and John, Biju and Anandasabari, K and Sanwal, Jaishri and Rajendran, Kusala and Kumar, Pankaj and Chopra, Sundeep (2018) On the paleoseismic evidence of the 1803 earthquake rupture (or lack of it) along the frontal thrust of the Kumaun Himalaya. In: TECTONOPHYSICS, 722 . pp. 227-234.

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Abstract

The foothills of the Himalaya bordered by the Main Frontal Thrust (MFT) continue to be a locus of paleo-seismological studies. One of such recent studies of trench stratigraphy near the central (Indian) Himalayan foothills (Malik et al., (2016) has reported multiple ruptures dated at 467-570, 1294-1587 and 1750-1932 CE. The last offset has been attributed to the Uttarkashi earthquake of 1803 and the penultimate faulting, with lesser confidence to an earthquake in 1505 CE. We tested these claims by logging an adjacent section on a shared scarp, and the new trench site, however, revealed a stratigraphic configuration partially in variance with from what has been reported in the earlier study. Our findings do not support the previous interpretation of the trench stratigraphy that suggested multiple displacements cutting across a varied set of deformed stratigraphic units leading up to the 1803 rupture. The current interpretation posits a single episode of a low-angle displacement at this site occurred between 1266 CE and 1636. Our results suggest a single medieval earthquake, conforming to what was reported from the previously studied neighboring sites to the east and west. The present study while reiterating a great medieval earthquake questions the assumption that the 1803 earthquake ruptured the MFT. Although a decollement earthquake, the 1803 rupture may have been arrested midway on the basal flat, and fell short of reaching the MFT, somewhat comparable to a suite of blind thrust earthquakes like the 1905 Kangra and the 1833 Nepal earthquakes.

Item Type:	Journal Article
Publication:	TECTONOPHYSICS
Publisher:	ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Additional Information:	Copy right for the article belong to ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Department/Centre:	Division of Electrical Sciences > Electrical Engineering
Date Deposited:	22 Mar 2018 13:57
Last Modified:	25 Oct 2018 08:44
URI:	http://eprints.iisc.ac.in/id/eprint/59256

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