北印度洋苏门答腊和莫克兰俯冲带地震海啸综述

Review of tsunami caused by large earthquakes along the Sumatra and Makran subduction zones in the North Indian Ocean

印度洋海啸发生的频率远低于太平洋,但2000年以来全球因地震引发的10个重大海啸有3个发生在印度洋区域。苏门答腊和莫克兰俯冲带是北印度洋中地震海啸活动较活跃的两个区域。在苏门答腊俯冲带北端,2004年12月26日和2005年3月28日分别发生了里氏9.0级和8.6级大地震,是1961年以来的第2及第4强震。前者引发了最大爬高50.9m的海啸,造成了历史上最大的海啸灾难;后者却只引发了最大4m的爬高。位置相近、震源机制相似的两次地震引发的海啸灾害完全不同的原因非常值得研究。近期研究表明莫克兰俯冲带的地震活动分为东西两段,东段的地震活动明显多于西段。东段于1945年发生过大海啸,莫克兰西段或是全段俯冲带未来是否会发生大地震与海啸值得深入探讨研究。

The frequency of tsunamis occurred in the Indian Ocean is much lower than that of the Pacific Ocean;in the past fifteen years,however,three out of ten major tsunamis triggered by the earthquake occurred in the Indian Ocean region.The Makran and the Sumatra subduction zones are the two active regions in the North Indian Ocean for tsunamigenic earthquakes.In the northern Sumatra subduction zone,two earthquakes with Mw9.0and8.6occurred on December26,2004and March28,2005,respectively,and they were ranked as the second and fourth largest earthquakes in the past half century.The2004event generated a tsunami disaster with the largest wave runup of50.9m,and resulted in the most devastating historical disaster,while the2005event only generated a maximum wave runup of4m.What caused the completely different tsunami scenarios by the two earthquakes with similar location and focal mechanism is worthy of study.Recent studies showed that the seismic activities along the Makran subduction zone were divided into two neighboring sections:the seismic activity of the eastern section is significantly stronger than the western section,and the1945tsunami was located in this section.Whether the western section,or the whole Makran subduction zone has the potential to rupture together and thus generate major tsunamis requires further investigations.