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First paleoseismic evidence for great surface‐rupturing earthquakes in the Bhutan Himalayas
Author(s) -
Le RouxMallouf Romain,
Ferry Matthieu,
Ritz JeanFrançois,
Berthet Théo,
Cattin Rodolphe,
Drukpa Dowchu
Publication year - 2016
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 - 10.1002/2015jb012733
Subject(s) - seismology , geology , excavation , magnitude (astronomy) , geography , archaeology , paleontology , physics , astronomy
The seismic behavior of the Himalayan arc between central Nepal and Arunachal Pradesh remains poorly understood due to the lack of observations concerning the timing and size of past major and great earthquakes in Bhutan. We present here the first paleoseismic study along the Himalayan topographic front conducted at two sites in southern central Bhutan. Paleoseismological excavations and related OxCal modeling reveal that Bhutan experienced at least two great earthquakes in the last millennium: one between the seventeenth and eighteenth century and one during medieval times, producing a total cumulative vertical offset greater than 10 m. Along with previous studies that reported similar medieval events in Central Nepal, Sikkim, and Assam, our investigations support the occurrence of either (i) a series of great earthquakes between A.D. 1025 and A.D. 1520 or (ii) a single giant earthquake between A.D. 1090 and A.D. 1145. In the latter case, the surface rupture may have reached a total length of ~800 km and could be associated with an earthquake of magnitude M w = 8.7–9.1.