We used GSN broadband waveforms downloaded from the NEIC waveform server. We analyzed 36 teleseismic broadband P waveforms, 30 broadband SH waveforms, and 68 long period surface waves selected based on data quality and azimuthal distribution. Waveforms are first converted to displacement by removing the instrument response and are then used to constrain the slip history using a finite fault inverse algorithm (Ji et al., 2002). We begin modeling using a hypocenter matching or adjusted slightly from the initial NEIC solution (Lon. = 73.629 deg.; Lat. = 34.493 deg., Dep. = 11.0 km), and a fault plane defined using either the rapid W-Phase moment tensor (for near-real time solutions), or the gCMT moment tensor (for historic solutions).
After comparing waveform fits based on the two planes of the input moment tensor, we find that the nodal plane (strike= 320.0 deg., dip= 29.0 deg.) fits the data better. The seismic moment release based upon this plane is 3.0e+27 dyne.cm (Mw = 7.6) using a 1D crustal model interpolated from CRUST2.0 (Bassin et al., 2000).
Surface projection of the slip distribution superimposed on GEBCO bathymetry. Red lines indicate major plate boundaries [Bird, 2003]. Gray circles, if present, are aftershock locations (up to 7 days), sized by magnitude.
Cross-section of slip distribution. The strike direction is indicated above each fault plane and the hypocenter location is denoted by a star. Slip amplitude is shown in color and the motion direction of the hanging wall relative to the footwall (rake angle) is indicated with arrows. Contours show the rupture initiation time in seconds.
Source time function, describing the rate of moment release with time after earthquake origin, relative to the peak moment rate (listed in the top right corner of the plot).
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This work is supported by the National Earthquake Information Center (NEIC) of United States Geological Survey. This web page is built and maintained by Dr. G. Hayes at the NEIC.