P.N.G Earthquake

Preliminary Results of Rupture Process for November 16, 2000 New Ireland Region, Papua New Guinea Earthquake

Inversion was made using teleseismic data (provided by IRIS-DMC)

We retrieved teleseismic body waves (P-waves and S-wave) data recorded at IRIS-dmc stations via Internet. 14 stations were used in the waveform inversion. We assumed a reference fault model :(strike, dip, rake) = (143, 83, 2) which is inferred from Teleseismic body wave analysis (EIC Seismological Note)

Result

The seismic moment Mo = 1.6 x 10**21 Nm (Mw 8.1);
The source duration T = 70 s;
Fault mechanism: (Strike, Dip, Slip)=(145, 84, -5) ;
Hypocenter: (lat.= 3.97S, lon.= 152.32E, depth= 35 km) [Fix].

The source process is characterized by a unilateral rupture propagation. The maximum slip amounts to 10 m at about 130 km Southeast from the hypocenter.

(Yagi and Kikuchi, 2000)

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.

Map View

Fig. 3: Hypocenter of the main-shock determined by USGS. Blue lines represent the extent of the fault plane used in our inversion.

Waveform comparison

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.

Fig. 6 : Slip distribution of the second large aftershock (2000/11/17).

If you have questions, please send to yuji@eri.u-tokyo.ac.jp or kikuchi@eri.u-tokyo.ac.jp.