2006年12月26日台湾南部滨海Ms7.2级地震破裂过程研究

2006年12月26日12点26分27秒(GMT)台湾南部滨海发生M_s7.2(Harvard CMT)级地震.震中位于台湾南部滨海之南海次板块与菲律宾海板块碰撞引发造山作用生成的海洋增生楔内， 这次地震是该区域百年来震级最大的地震.我们利用中国数字地震台网(CSDN)和美国地震学联合研究所(IRIS) 提供的上地幔及远场范围宽频带P波垂向记录资料，基于点源和有限断层模型进行波形拟合反演，获得这次地震的震源机制解并给出了震源破裂过程.反演结果表明，本次地震为东倾正断层兼小幅度走滑破裂事件， 断层面走向为341.5°，倾角为77.9°，震源深度6 km.所得正断层震源机制解表明，地震可能与板块的拆离（break-off）作用引发的在台湾造山带局部存在伸张作用力有关.

Rupture process of southern Taiwan offshore Ms7.2 earthquake of Dec. 12, 2006

The rupture process of the Dec. 12, 2006(12h 26m 27sec) Taiwan earthquake (M_s7.2 Harvard CMT) is investigated by the point source and finite fault model using upper mantle and far field broadband P wave records retrieved from IRIS and China Digital Seismic Network. The earthquake was the largest to have struck the southern Taiwan offshore in the recent century, the epicenter was situated in the collision boundary of Eurasia plate and Philippine Sea plate. The results indicate that the earthquake occurred on an east-dipping normal fault with a small amount of strike slip. The fault plane has a strike of 341.5°, a dip of 77.9° and the focal depth is 6 km. We proposed that this earthquake was triggered by extensional stress induced by the break off of Eurasia plate that subducted under Philippine Sea plate.