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2004年12月26日在印度洋发生的苏门答腊—安达曼特大地震其强烈的震动和随之而来的海啸导致了大规模的破坏和大量人员伤亡。针对这一地震的一些研究提出不同的断层部分其破裂速度也不尽相同,沿1200km长的破裂长度观测到了快慢两种破裂速度。地震期间破裂速度的变化可能说明巨型冲断层摩擦条件沿走向的变化可能会影响到这个消减带上的其他地震。先前对全球消减带系所做的研究表明随深度而变的摩擦条件产生于沿断层带的不均匀介质条件。在环太平洋消减带的很多地区,沿着巨型消减冲断层的浅源地震较深源地震具有更长尺度的震源持续时间,可能是由于摩擦条件随深度变化所致。本文重点探讨苏门答腊—安达曼巨型冲断层上逆冲性质的地震,调查2004年Mw>6.0级地震的余震以及在1992～2004年间该地区发生的地震。确定了这组地震的震源持续时间、深度和滑动分布以探索震源参数和摩擦条件沿走向和随深度而变化的可能性。这些地震的震源参数有随深度而变的迹象,较浅的地震持续时间更长,这与先前在全球范围的研究一致。由于先前大地震的震源参数与震后的相似,所以这种关系没有明显的时间变化。沿走向的模式显示出破裂带南部几个地震有持续时间长的特征,但是没有破裂带北部缓慢破裂的强有力证据。断层带特征的任何长期变化不大可能影响2004年地震可能的缓慢破裂过程。
The massive earthquake and subsequent tsunami that took place in the Indian Ocean on December 26, 2004, in the Sumatra-Andaman Earthquake resulted in massive destruction and heavy casualties. Some researches on this earthquake suggest that the different fault sections have different rupture rates, and the rupture velocities are observed along the rupture length of 1200 km. The variation of the rupture velocity during the earthquake may indicate that the variation along the strike of the giant thrust fault may affect other earthquakes on this abatement zone. Previous studies of global abatement bands have shown that depth-dependent frictional conditions result from inhomogeneous media conditions along the fault zone. In many areas of the Pacific Rim depletion zone, the source duration of the deeper-scale earthquakes along the meso-depleted thrusts may be due to the varying depth of the frictional conditions. This paper focuses on the thrust-type earthquakes on the Sumatra-Andaman megather thrust fault. The aftershocks of Mw> 6.0 earthquake in 2004 and the earthquakes in the area from 1992 to 2004 were investigated. The duration, depth and slip distribution of the sources of this group of earthquakes are determined to explore the potential of source parameters and friction conditions along the strike and depth. The source parameters of these earthquakes have a sign of depth change, and the shallower earthquakes last longer, consistent with previous studies worldwide. Since the source parameters of the previous major earthquakes are similar to those after the earthquake, there is no significant temporal change in this relationship. The strike pattern shows that several earthquakes south of the rupture zone have the characteristics of long duration, but there is no strong evidence of slow rupture in the northern rupture zone. Any long-term changes in the characteristics of the fault zone are unlikely to affect the possible slow-break process of the 2004 earthquake.