Medieval pulse of great earthquakes in the central Himalaya: Viewing past activities on the frontal thrust

Rajendran, CP and John, Biju and Rajendran, Kusala (2015) Medieval pulse of great earthquakes in the central Himalaya: Viewing past activities on the frontal thrust. In: JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 120 (3). pp. 1623-1641.

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Abstract

The Himalaya has experienced three great earthquakes during the last century1934 Nepal-Bihar, 1950 Upper Assam, and arguably the 1905 Kangra. Focus here is on the central Himalayan segment between the 1905 and the 1934 ruptures, where previous studies have identified a great earthquake between thirteenth and sixteenth centuries. Historical data suggest damaging earthquakes in A.D. 1255, 1344, 1505, 1803, and 1833, although their sources and magnitudes remain debated. We present new evidence for a great earthquake from a trench across the base of a 13m high scarp near Ramnagar at the Himalayan Frontal Thrust. The section exposed four south verging fault strands and a backthrust offsetting a broad spectrum of lithounits, including colluvial deposits. Age data suggest that the last great earthquake in the central Himalaya most likely occurred between A.D. 1259 and 1433. While evidence for this rupture is unmistakable, the stratigraphic clues imply an earlier event, which can most tentatively be placed between A.D. 1050 and 1250. The postulated existence of this earlier event, however, requires further validation. If the two-earthquake scenario is realistic, then the successive ruptures may have occurred in close intervals and were sourced on adjacent segments that overlapped at the trench site. Rupture(s) identified in the trench closely correlate with two damaging earthquakes of 1255 and 1344 reported from Nepal. The present study suggests that the frontal thrust in central Himalaya may have remained seismically inactive during the last similar to 700years. Considering this long elapsed time, a great earthquake may be due in the region.

Item Type:	Journal Article
Publication:	JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
Publisher:	AMER GEOPHYSICAL UNION
Additional Information:	Copy right for this article belongs to the AMER GEOPHYSICAL UNION, 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA
Keywords:	paleoseismology; seismic gap; great earthquakes; central Himalaya; earthquake recurrence
Department/Centre:	Division of Mechanical Sciences > Centre for Earth Sciences
Date Deposited:	22 May 2015 07:47
Last Modified:	22 May 2015 07:47
URI:	http://eprints.iisc.ac.in/id/eprint/51575

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