Abstract: The rupture process of the 2008 Wenchuan M_S8.0 earthquake is derived by joint inversion using near-field 1-Hz GPS, strong motion waveforms and the P-phase seismograms recorded by the Global Seismographic Network stations, considering the constrained conditions of spatial-temporal slip, ABIC criterion and a priori constraints on the rupture slip directions. A unified source model is obtained, which reflects multiple aspects of the rupture process of the Wenchuan earthquake. The inversion results show that there are 4 dominant rupture zones. The first one is 40~120 km northeastward away from the focus with maximum slip value at ~10 m, and major slips are in the depth of 2~20 km, with rupture reaching to the surface. The second primary slip zone is also located at southern segment of the Longmenshan fault, with maximum slip value at ~6 m. The other two primary slip zones are at the northern segment of the Longmenshan fault, with smaller maximum slip values at 4 m. The length of the rupture zones of slip values more than 1 m is larger than 70 km in the strike direction. The estimated seismic moment is 9.5×10²¹ Nm, with a moment magnitude equivalent to M_W7.95. Snapshots of the rupture process demonstrate that the Wenchuan earthquake ruptured unilaterally, initiated at the depth of 16 km beneath Wenchuan zone, and propagated consistently northeastward, with an entire rupture duration of ~120 seconds. During the 0~10 seconds after the initiation, the slip is dominant around the earthquake focus, with slip values around ~1.0 m, and then the rupture continued to propagate northeastward. The duration of 20~40 seconds is a primary temporal period of rupture. In the period of 40~60 seconds, the rupture propagated to the intersection of the southern and northern segments of the Longmenshan fault. During the 80~90 seconds, the maximum slip values began to decrease. During the 100~110 seconds, slip decreased to ~0.5 m. During the 110~120 seconds, slip decreased to ~0.1 m. The addition of near-field 1-Hz GPS waveforms to the inversion of strong motion and teleseismic P-phase seismograms can increase the resolution of rupture slip models, especially for the shallow zones, with a slightly larger maximum slip values than the inversion result without 1-Hz GPS waveforms involved.

Key words: The 2008 Wenchuan M_S8.0 earthquake, High-rate GPS, Rupture model of earthquake source, Coseismic deformation