Historic Earthquakes: Finite Fault Model

Magnitude 7.3 PAPUA, INDONESIA
2004 February 07 02:42:35 UTC

Preliminary Rupture Model
Contributed by Chen Ji, Caltech

Nineteen broadband seismograms were selected from a realtime dataset provided by NEIC data center to study this earthquake. The Green's functions were generated by using a crust model interpolated from crust2.0 model [Laske et al., 2001] at the PDE hypocenter location. A simulated annealing finite inversion procedure using wavelet transform [Ji et al., 2002] was applied to investigate the spatial-temporal rupture history of this earthquake. Two fault planes were first built by using the moment tensor solution of Caltech [Polet, 2004]. Finite fault inversions were then preformed simultaneously to find the plane that fits the data better.Both of them explain the data well but the fault plane (strike= 355, dip=80) is better.

The inverse result explains data well (Figure 1.). The seismic moment of this earthquake is 9.8x10^26 dyne.cm, or a moment magnitude of 7.25.

Earthquake Location
Figure 1: Earthquake Location

Comparison of teleseismic body waves (black) and
synthetic seismograms (red)
Comparison of teleseismic body waves (black) and synthetic seismograms (red). The epicenter distance and azimuth of each station are indicated at the beginning portion of records with the azimuth above. The peak amplitude of each record is showed above end of each trace in micrometer and used to normalize both data and synthetic seismogram.

Finite fault slip distribution.
Finite fault slip distribution. The color shows the slip amplitude and contour in 5 sec interval shows the rupture front.

Slip Distribution Data