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2004年12月26日的苏门答腊—安达曼地震是自现代空间大地测量和宽频带地震学出现以来发生的第一个巨大地震(矩震级Mw>9·0)。它为研究这种巨大且罕见的事件的特性提供了前所未有的机会。我们根据在苏门答腊西北部的近场全球定位系统(GPS)的探测结果并结合原地和远处的珊瑚礁垂直运动的观测,对这次事件造成的地表位移进行了估计。结果表明,该地震是由范围长>1500km、宽<150km范围内的巽他俯冲巨型逆断层破裂造成的。巨型逆断层在苏门答腊北部的近海滑动超过了20m,大部分的滑动深度不超过30km。对比大地测量学和地震学推断的滑动分布,发现在500秒长破裂发生之后的1·5个月内,断层滑动增加了~30%。在我们再次布设GPS测点之前,有震的和无震的滑动都出现在了巨型逆断层的浅部,那里是亚齐大海啸的源头。滑动在断层东南缘的锡默卢岛之下沿走向突然尖灭,在该处地震成核,并且2002年的晚期在此曾发生过一次Mw=7·2级地震。此外,该边缘也与2005年3月28日Mw=8·7的尼亚斯—锡默卢地震破裂的最北端相邻接。
The Sumatra-Andaman earthquake on December 26, 2004 was the first major earthquake (moment magnitude Mw> 9.0) that occurred since the advent of geodesy and broadband seismology in modern times. It offers an unprecedented opportunity to study the characteristics of such a huge and rare event. Based on the results of near-field global positioning system (GPS) surveys in northwestern Sumatra, combined with observations of the vertical movement of coral reefs, both in situ and in remote locations, we estimated the surface displacements caused by this incident. The results show that the earthquake is caused by the giant thrust fault of 巽 He subduction in the range of> 1500 km and width <150 km. The giant thrust fault slipped over 20m off the coast of northern Sumatra, most of the depth of which did not exceed 30km. In contrast to the inferred geostatistics of geodesy and slippage, it was found that fault slip increased by ~ 30% within 1.5 months after a 500 second rupture. Before we lay out the GPS measurements again, both the quake-prone and the slippage-free slides appeared in the shallow depths of the giant reverse faults, the source of the tsunami of Aceh. The slip slipped along the Semeru Island on the southeastern margin of the fault along a sudden pinch-out where the earthquake was nucleated and in the late 2002 there was a Mw = 7.2 earthquake here. In addition, the margin is also adjacent to the northernmost tip of the Nias-Semeru earthquake ruptured on Mw 28 of March 28, 2005.