Rupture history of the 2010 Ms 7.1 Yushu earthquake by joint inversion of teleseismic data and InSAR measurements
Résumé
We applied a joint inversion of teleseismic data and InSAR measurements, aiming at obtaining a robust rupture process and slip distribution of the 2010 Yushu earthquake, through reducing the trade-off between slip timing and location. With the condition of the final static deformation of InSAR measurements, the rupture history can be achieved with more confidence. Surface offset constraint is also applied to our inversion. Through synthetic data inversion we find that InSAR data can resolve better fault slip at near surface depth range of 0-15 km than teleseismic data; yet it has much poorer resolution at near hypocenter area, where teleseismic data has a relatively better resolution. Our final joint inversion results show that the 2010 Yushu earthquake has an essential rupture time around 20 s, during which 90% of the seismic moment has been released. Two peak energy releasing moments occur at 8 and 12 s after the earthquake initiation, respectively. The fault slip breaks the surface at most segments of the total 76 km fault model and the maximum slip reaches 2.2 m. We also find two peak-slip asperities, one at near hypocentral area, mainly distributed at depth around 10-15 km; the other distributed in a large area at the eastern segments at near surface. Our most robust estimation of the seismic moment reaches 2.30 × 1019 N.m, equivalent to a moment magnitude of Mw 6.9.