Paleoseismological Findings at a New Trench Indicate the 1714 M8.1 Earthquake Ruptured the Main Frontal Thrust Over all the Bhutan Himalaya

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License: CC BY 4.0
Serval ID
serval:BIB_6C9020376771
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Paleoseismological Findings at a New Trench Indicate the 1714 M8.1 Earthquake Ruptured the Main Frontal Thrust Over all the Bhutan Himalaya
Journal
Frontiers in Earth Science
Author(s)
Zhao Yuqiu, Grujic Djordje, Baruah Santanu, Drukpa Dawchu, Elkadi Joanne, Hetényi György, King Georgina E., Mildon Zoë K., Nepal Nityam, Welte Caroline
ISSN
2296-6463
Publication state
Published
Issued date
05/08/2021
Peer-reviewed
Oui
Volume
9
Language
english
Abstract
The 1714 Bhutan earthquake was one of the largest in the Himalaya in the last millennium. We show that the surface rupture caused by this earthquake extended further to the east than previously known, it was at least 175 km long, with slip exceeding 11 m at our study site. The age of the surface rupture was constrained by a combination of radiocarbon and traditional optically stimulated luminescence dating of affected river sediments. Computations using empirical scaling relationships, fitting historical observations and paleoseismic data, yielded a plausible magnitude of Mw 8.1 ± 0.4 and placed the hypocentre of the 1714 Bhutan earthquake on the flat segment of the Main Himalayan Thrust (MHT), the basal décollement of the Himalayan orogen. Calculations of Coulomb stress transfer indicate that great earthquakes along the leading part of the MHT would cause surface rupture. In contrast, distal earthquakes may not immediately trigger surface rupture, although they would increase the stresses in the leading part of the MHT, facilitating future surface-rupturing earthquakes. Frontal earthquakes would also transfer stress into the modern foreland basin facilitating southward propagation of the MHT as a blind basal décollement. In conclusion, studies of surface-rupturing events alone likely underestimate the seismic slip along the Himalayan megathrust.
Keywords
surface rupture, stress transfer, Himalaya, optically stimulated luminescence dating, radiocarbon dating
Web of science
Open Access
Yes
Create date
06/09/2021 8:40
Last modification date
24/12/2022 6:44
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