????GPS??InSAR??????Mw7.9???????????

??????8.0????????????????????????????????????λ??????????????η????????ν??????????????????8.0??????GPS??InSAR????α??????????????????????????????????????????1?????????????????GPS??InSAR??????????α????????????97.27%;2??????????????????????????????????????0??20 km??????????????λ???????????????????????????????????????????0??20 km???????????????????10 m????????10??15 km?????????????6.5 m??3??????????????????????????????????????????????????????????103??????????????????????121????????????????????138??????????????????????????105??4?????????????????8.7??10 ²⁰ Nm???????Mw7.9??

INVERSION OF SLIP DISTRIBUTION OF 2008 WENCHUAN Mw7.9 EARTHQUAKE CONSTRAINED JOINTLY BY InSAR AND GPS MEASUREMENTS

A two-segment fault model for the May 12,2008 Wenchuan Ms8.0 earthquake based on field investigations and precisely relocated aftershocks had established. The model is consistent with the surface rupture traces seen in the field at most sites along the fault. It contains two fractures with linearly varied dips from 70° to 33° and from 60° to 20°, respectively and they converge into one shear belt at the depth of 28 km. Then use this fault model as the constraint to invert the coseismic slip distribution using GPS data as well as InSAR measurements solo or jointly. The results show a robust slip distribution can be obtained by jointly using GPS and InSAR data. The deformation by forward modeling matches well the GPS data and InSAR deformation, with a relatively small total RMS of 9-11 cm. The inverted slip distribution is confined to a depth range 0-20 km and the maximum slip is 10 m. Among the largest slip areas, the Beichuan area has relatively concentrated slip and shallower depth（0-10 km）than other areas. This may be the reason that the Beichuan area was most severely destroyed by the earthquake. The inverted rake distribution shows that there is a transform of fault slide along the direction of SW NE. It is primarily thrusting with some right lateral component from nearby the epicenter to Beichuan, and changes into dominantly right-lateral slip with little thrusting or even pure right lateral slip at the Qingchuan area in northeast. The mean rakes range from 103°to 121°and 138°. The inverted seismic moment tensor M0 is 8.7×10 ²⁰ Nm, and the inverted moment magnitude scale Mw is 7.9.