Preliminary Results of Rupture Process for the March 28, 2005 NORTHERN
SUMATRA, INDONESIA Earthquake
Inversion was made using teleseismic data (provided by IRIS-DMC)
On March 28, 2005, great thrust-faulting earthquake (M = 8.7) occurred
in Sumatra, Indonesia. This earthquake located on the interface between
the India and Burma plates where India plate is subducting beneath the
overriding Burma plate at a rate of about 4-6 cm/year. I retrieved teleseismic
body waves (P-waves) data recorded at IRIS-dmc stations via Internet. 19
stations were selected from the viewpoint of good coverage, and used in
the waveform inversion with ABIC (Fukahata et al., 2003, 2004; Yagi et
The seismic moment Mo = 1.6 x 10**22 Nm (Mw 8.7);
The source duration T = 150 s;
(strike, dip, rake) = (329, 14, 115)
Hypocenter: (Lat. = 2.065N, Lon. = 97.010E, depth= 28 km).
[The epicenter of the main-shock was determined by USGS]
The rupture nucleated on south side of 2004 Sumatra Great Earthquake, and
propagated 300 km to the southeast. The rupture propagated mainly along
trench axis.The maximum dislocation is about 10 m.
Since I used the teleseismic body wave, the resolution of space is not so good. The maximum dislocation and fault area will be revised using the near-field data.
Distribution of fault-slip
Figure : (upper left) Focal mechanism; (upper right) Total moment-rate
function; (lower) Distribution of coseismic slip. Star indicates the location
of the initial break.
Figure: Hypocenter of the main-shock determined by USGS.
Figure : Comparison of the observed waveform (Black) with the calculated waveform (Red).
The numbers below the station code indicate maximum amplitude in microns.
The start time of the traces is lined-up at 10 (s) before the P-wave arrival.
Figure : Teleseismic stations used in inversion. The star represents the
epicenter of the main-shock.
Fukahata, Y., Y. Yagi, and M. Matsu'ura,
Waveform inversion for seismic source processes using
ABIC with two sorts of prior constraints: Comparison
between proper and improper formulations, GRL 30, 10.1029/2002GL016293, 2003.
Fukahata, Y.; A. Nishitani; M. Matsu'ura, Geodetic data inversion using ABIC to
estimate slip history during one earthquake cycle with viscoelastic
slip-response functions, Geophys. J. Int., 156, 140-153, 2004.
Yagi, Yagi ; T. Mikumo; J. Pacheco, Source
rupture process of the Tecoman, Colima, Mexico earthquake of January 22, 2003,
determined by joint inversion of teleseismic body wave and near-field data
(PDF), submited to Bull. Seism. Soc. Am., 2003.
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Last Updated: March 29, 2005