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The 2 March 2016 Wharton Basin M w 7.8 earthquake: High stress drop north‐south strike‐slip rupture in the diffuse oceanic deformation zone between the Indian and Australian Plates
Author(s) -
Lay Thorne,
Ye Lingling,
Ammon Charles J.,
Dunham Audrey,
Koper Keith D.
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl069931
Subject(s) - intraplate earthquake , seismology , geology , aftershock , slip (aerodynamics) , fault (geology) , structural basin , geomorphology , tectonics , physics , thermodynamics
The diffuse deformation zone between the Indian and Australian plates has hosted numerous major and great earthquakes during the seismological record, including the 11 April 2012 M w 8.6 event, the largest recorded intraplate earthquake. On 2 March 2016, an M w 7.8 strike‐slip faulting earthquake occurred in the northwestern Wharton Basin, in a region bracketed by north‐south trending fracture zones with no previously recorded large event nearby. Despite the large magnitude, only minor source finiteness is evident in aftershock locations or resolvable from seismic wave processing including high‐frequency P wave backprojections and Love wave directivity analysis. Our analyses indicate that the event ruptured bilaterally on a north‐south trending fault over a length of up to 70 km, with rupture speed of ≤ 2 km/s, and a total duration of ~35 s. The estimated stress drop, ~20 MPa, is high, comparable to estimates for other large events in this broad intraplate oceanic deformation zone.