Simultaneous Rupture Along Two Conjugate Planes of the Wharton Basin Earthquake
D. P. Robinson,
C. Henry,
S. Das,*
J. H. Woodhouse
Analysis of broadband teleseismic data shows that the 18 June 2000 Wharton Basin earthquake, a moment magnitude 7.8 intraplate event in the region of diffuse deformation separating the Indian and
Australian plates, consisted of two subevents that simultaneously ruptured two near-conjugate planes. This mode of rupture accommodates shortening by a mechanism different from that previously
known elsewhere in the region. The larger subevent occurred on a fossil fracture zone, with a relatively high stress drop of about 20 megapascals, showing that large stresses can accumulate in regions of distributed deformation.
Department of Earth Sciences, University of Oxford, Parks Road,
Oxford OX1 3PR, UK.
*
To whom correspondence should be addressed. E-mail:
das{at}earth.ox.ac.uk