论文部分内容阅读
海地的Enriquillo-Plantain Garden断裂带被认为是主要板块边界断层系之一。走滑性质的Enriquillo-Plantain Garden断层带紧邻太子港市而过,起初被认为是2010年1月12日M_w7.0级地震的发震断层。海地经历了1751年和1770年的大地震,但人们对Enriquillo-Plantain Garden断层带在这些地震中起的作用知之甚少。我们利用卫星影像、航空照片、激光雷达和野外调查这些方式证实了Enriquillo-Plantain Garden断层的第四纪活动性。我们指出断层晚第四纪左旋位移量达160m,并发现了一组可能与18世纪的一次地震有关的小位移,其位移量从1.3m到3.3m不等。小位移的幅度显示18世纪的那次历史地震大于M_w7.0,但是很可能小于M_w7.6。我们没有发现与2010年大地震有关的明显的地表破裂。没有地表破裂,加上其他的地震学、地质学、大地测量学方面的观察结果,表明2010年大地震时Enriquillo-Plantain Garden断层即使有,也只是很少的累积应变得到释放。这些结论证实,Enriquillo-Plantain Garden断层仍然具有很高的地震危险性。
The Enriquillo-Plantain Garden fault zone in Haiti is considered as one of the major plate boundary faults. The strike-slip Enriquillo-Plantain Garden fault zone, immediately after Port-au-Prince, was originally thought of as a seismogenic fault on the M_w7.0 earthquake on January 12, 2010. Haiti experienced large earthquakes in 1751 and 1770, but little is known about the role of the Enriquillo-Plantain Garden fault zone in these earthquakes. We demonstrate the Quaternary activity of the Enriquillo-Plantain Garden fault using satellite imagery, aerial photography, lidar, and field surveys. We point out that the Late Quaternary left-hand displacement of the fault reached 160m and a set of small displacements that may be related to an 18th-century earthquake were found with displacements ranging from 1.3m to 3.3m. The magnitude of small displacements shows that the 18th century historical earthquake was larger than M_w7.0, but probably less than M_w7.6. We did not find any apparent surface ruptures associated with the 2010 earthquake. The absence of surface ruptures, combined with other seismological, geologic and geodesy observations, indicates that, if any, the Enriquillo-Plantain Garden fault was released during the 2010 earthquake, only a small cumulative strain was released. These conclusions confirm that the Enriquillo-Plantain Garden fault still poses a high seismic risk.