Aftershock distribution of the 26 December 2004 Sumatra-Andaman earthquake from ocean bottom seismographic observation
Aftershock distribution of the 26 December 2004 Sumatra-Andaman earthquake from ocean bottom seismographic observation
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DOI：
10.1186/bf03353367
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发表时间：
2006-01-01
影响因子：
3
通讯作者：
Suyehiro, K
中科院分区：
文献类型：
--
作者：
Araki, E;Shinohara, M;Suyehiro, K
2005年2月至3月，我们在2004年12月26日苏门答腊安达曼地震的破裂区部署了OBS网络。我们放置了17个短期OBBS和2个长期OBBS，并在观察19-22天后恢复OBBS。由17个OBS的10天资料得到的震源分布揭示了苏门答腊岛近海余震地震活动的详细结构。余震地震活动与俯冲板开始40公里内从巽他海沟轴，它停止在亚齐盆地下50公里的深度，约240公里内从海沟轴。距海沟轴120-170公里范围内的余震由一个倾角为10-12度的面组成，以倾张型机制为主。在亚齐盆地西南边缘以外，余震活动性增强，以倾滑型地震为主，倾角略有增大，为15-20度。在苏门答腊海沟向内70公里处、海沟向内110公里处和亚齐盆地南部确定了三个沿弧浅层地震活动带。这些位置对应于增生棱镜中陡峭的地形斜坡，表明苏门答腊岛近海增生棱镜目前的演化活动。
We deployed an OBS network in February-March 2005 in the rupture area of the Sumatra Andaman earthquake on 26 December 2004. We placed 17 short-term OBSs and two long-term OBSs, and recovered OBSs after observation for 19-22 days. The hypocenter distribution from 10-day data of 17 OBS revealed the detailed structure of aftershock seismicity offshore of Sumatra Island. Aftershock seismicity associated with the subducting slab starts 40 km inward from the Sunda trench axis; it ceases at 50 km depth beneath the Aceh Basin, approximately 240 km inward from the trench axis. Aftershocks in 120-170 km from the trench axis consist of a surface with a dip of 10-12 degrees dominated by a dip-extension type mechanism. Beyond the southwestern edge of the Aceh Basin, the aftershock activity becomes higher, and dominated by dip-slip type earthquakes, with a slightly increased dipping angle of 15-20 degrees. Three along-arc bands of shallow seismicity were identified at 70 km inward from the Sumatra trench, 110 km inward from the trench, and in the south of the Aceh Basin. These locations correspond to steep topographic slopes in the accretionary prism, suggesting the present evolutional activity of the accretionary prism offshore Sumatra Island.