New Constraints on the Mechanism and Rupture Area for the 1905 Mw 7.8 Kangra Earthquake, Northwest Himalaya

Document Type

Article

Department or Administrative Unit

Geological Sciences

Publication Date

9-25-2017

Abstract

Previous interpretations of the 4 April 1905 Mw 7.8±0.2 Kangra earthquake assumed pure thrust slip on a gently dipping plane with dimensions on the order of 55 km down‐dip and 100–150 km along strike. However, the identification of recent surface slip on a 60‐km‐long strike‐slip fault, the Kangra Valley fault (KVF), above the northwestern corner of the inferred thrust, raises the intriguing possibility that moment release in 1905 may have been partly, or wholly attributable to dextral slip. We use geodetic strain data to constrain maximum dextral slip on the mapped fault trace of the KVF to less than 0.6 m, equivalent to an Mw≤6.8 earthquake, but find that 1.1±0.25  m of subsurface reverse slip occurred along ≈190  km of the mapped Jawalmukhi thrust fault. Reevaluated macroseismic data for the 1905 earthquake and insights from the distribution of felt intensities above the 2015 Gorkha earthquake, however, suggest that the Kangra coseismic rupture extended only ≈100  km along strike. In the time period following the 1905 earthquake, afterslip to the southeast of the mainshock either preceded or accompanied a large aftershock sequence (⁠6.4w<6.8⁠) located near the down‐dip end of this extended slip zone.

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This article was originally published in Bulletin of the Seismological Society of America. The full-text article from the publisher can be found here.

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Journal

Bulletin of the Seismological Society of America

Rights

Copyright © 2017 Seismological Society of America

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