Preliminary Results of Rupture Process for
The 2002 NORTHERN SUMATRA, INDONESIA EARTHQUAKE
Inversion was made using teleseismic data (provided by IRIS-DMC)
I retrieved teleseismic body waves (P-waves) data recorded at
IRIS-dmc stations via Internet. 19 stations were used in the
We assumed a reference fault model :(strike, dip, rake) = (298, 8, 72)
which is inferred from the Harvard CMT solution.
This focal mechanism is consistent with release of stress buildup
on the inter-plate boundary in Subdction zone.
The seismic moment Mo = 1.1e20 Nm (Mw 7.3);
The source duration T = 30 s;
Fault mechanism: (Strike, Dip, Slip)=(298, 8, 75) ;
Hypocenter: (lat.= 3.02N, lon.= 96.18E, depth= 16 km).
Rupture propagated upward and unilateral.
Two asperities (large slip areas) are identified.
The maximum dislocation is about 1.6 m.
Distribution of fault-slip
Fig. 1 : (upper left) Focal mechanism; (upper middle) Total moment-rate function; (lower) Distribution of coseismic slip. Star indicates the location of the initial break.
Snapshot of fault-slip
Fig. 2 : Snapshots of the interval dislocation.
Fig. 3: Hypocenter of the main-shock determined by USGS.
Blue lines represent the extent of the fault plane used in our inversion.
Fig. 4 : 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- or S-wave arrival.
Fig. 5 : Telesesimic stations used in our inversion (Azimuthal Equidistant Projection).
The star represents the epicenter of the main-shock.
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Last Updated: 21 Nov. 2002