Investigation on the rupture behavior of the 2001 Kunlun and 1997 Manyi, China, earthquakes

We examine the rupture processes of the 14 November, 2001(09:26:10 GMT) Kunlun earthquake (Ms=8.1), and 8 November 1997 (Mw=7.6) Manyi earthquake to investigate the temporal and spatial slip distribution along the ruptured faults. The 2001 Kunlun earthquake struck the northern Tibetan plateau, China, near the Kusai Hu segment of the Kunlun Fault. Field investigation shows this earthquake produced a surface ruptured of about 400 km long and a maximum strike-slip motion of 16.3 m. The 1997 Manyi earthquake occurred at a Quaternary fault to the west of the 2001 Kunlun rupture zone. The Manyi earthquake produced a 170-km-long surface rupture zone with a maximum left-lateral strike-slip of 7 m. These large rupture lengths and strike-slip movements, including 1937 M7.5 Tuosho lake earthquake prior 1997 event, show the possible partitions of the Kunlun fault deformation into eastward extrusion of Tibet. To understand the ruptured behavior of the 1997 Manyi and 2001 Kunlun earthquakes, we investigated the teleseismic waveforms accommodated with field observations to obtain the temporal/spatial slip distribution of the ruptured faults. Two components of slip, strike-slip and dip-slip, were inverted, allowing the change of rake angle through rupture. A multiple-time window was introduced to make the source duration close to reality. For the 2001 Kunlun earthquake, we revealed a fault geometry with strike of N100E, and the dip of 82° . The rupture velocity was 3 km/s with source duration of 33 s. The optimum results show that the strike-slip motions took place in the most portion of the fault with a maximum displacement of 7 m at about 240 km east from the epicenter. Three distinct asperities were found with total seismic moment of 8.69e+20Nm (Mw=7.9). The study on the 1997 Manyi earthquake is undergoing. The rupture behavior of these two earthquakes will provide important information not only their possible implication on tectonic involvement of Kunlun fault to eastward extrusion of Tibet, but also the earthquake rupture physics toward possible stress triggering along a fault system.