Reconciling Short-period and Broadband Source Models of the Mw 8.7 Indian Ocean Earthquake of 11 April 2012

The Mw 8.7 Indian Ocean earthquake of April 11, 2012 occurred in a remote region of the world, limiting the geophysical and geological methods available to study its rupture properties. Lacking near-source networks of seismic and geodetic instruments, teleseismic observations of the earthquake have provided the most important constraints on the space-time history of the rupture. Perhaps because of the non-uniqueness inherent in using teleseismic data to infer earthquake rupture properties, several distinct source models have been proposed, all involving multiple fault planes. Here we evaluate four finite-fault slip models recently developed from a combination of broadband teleseismic waveforms and regional distance, high-rate GPS data for consistency with constraints from back-projection of high-passed teleseismic data. Although the back-projections are sensitive primarily to variations in slip-rate, some level of consistency with the slip models is expected. The four slip models have nearly equivalent fits to the broadband seismic and geodetic data, but were constructed with different assumptions about fault orientation, number of faults, and rupture velocity, including one model that prescribes a supershear rupture velocity, as has been proposed by some authors. Synthetic waveforms from the slip models are computed for the same sets of seismometers in Europe and Japan that were used to back-project the original data, and the synthetic back-projections are compared to the data back-projections in order to discriminate among the various assumptions used to construct the finite-fault slip models.