Aftershock seismicity of the 27 February 2010 Mw 8.8 Maule earthquake rupture zone
Aftershock seismicity of the 27 February 2010 Mw 8.8 Maule earthquake rupture zone
复制标题
DOI：
10.1016/j.epsl.2011.11.034
复制
发表时间：
2012-02-01
影响因子：
5.3
通讯作者：
Beck, Susan
中科院分区：
文献类型：
--
作者：
Lange, Dietrich;Tilmann, Frederik;Beck, Susan
2010 年 2 月 27 日，智利中部发生的 8.8 级马乌莱地震使一个地震间隙破裂，该间隙自 1835 年以来积累了巨大的应变。主震发生后不久，沿着整个破裂带安装了密集的临时地震台网，以捕获余震活动。在这里，我们提出了基于自动检测算法和拾取引擎的余震分布和第一运动极性震源机制。通过处理 2010 年 3 月 15 日至 9 月 30 日期间来自 IRIS、IPGP、GFZ 和利物浦大学台站的地震数据，我们确定了 20,205 个震级 M-w 在 1 至 5.5 之间的震源。地震活动分为六组： 1.) 正常断层外隆事件 2.) 一组浅层板块界面地震活动，在 25-35 公里深度和距离海沟 50-120 公里处明显，剖面之间存在一些变化。沿着走向，余震主要发生在同震滑移带内，但向北延伸约 50 公里，且主要具有浅倾逆冲机制。沿着倾角，事件要么在同震滑移区域内，要么从同震滑移区域向下倾，具体取决于所使用的同震滑移模型。 3.) 在 40-50 公里深度处观察到第三个地震活动带，在 150-160 公里海沟垂直距离处进一步下倾，并在 150-160 公里海沟垂直距离处进一步内陆，主要是浅倾角（类似于 28 度）推力震源机制，表明板块界面的破裂显着下倾同震破裂，并且可能在大陆莫霍面与板块界面的交点之上。 4.) 南纬 36 度以北存在一组深度介于 80 至 120 公里之间的深层中深度事件。在马乌莱段内，地震间期的大部分事件都源自该深度范围。 5.) 岩浆弧表现出少量的地壳地震活动，但在 2010 年 M-w 8.8 Maule 地震后似乎并未表现出明显增强的活动。 6.) 在 Pichilemu 地区（类似于南纬 34.5 度）发现了明显的地壳余震活动，主要是正常的断层机制。这些地壳事件发生在大约 30 公里宽的区域，其边界急剧倾斜，且方向与海沟倾斜。最佳位置事件描述了一架飞机向西南倾斜，与 2010 年 3 月 11 日发生的大型正断层余震 (M-w = 6.9) 的焦平面之一一致。(C) 2011 Elsevier B.V. 保留所有权利。
On 27 February 2010 the M-w 8.8 Maule earthquake in Central Chile ruptured a seismic gap where significant strain had accumulated since 1835. Shortly after the mainshock a dense network of temporary seismic stations was installed along the whole rupture zone in order to capture the aftershock activity. Here, we present the aftershock distribution and first motion polarity focal mechanisms based on automatic detection algorithms and picking engines. By processing the seismic data between 15 March and 30 September 2010 from stations from IRIS, IPGP, GFZ and University of Liverpool we determined 20,205 hypocentres with magnitudes M-w between 1 and 5.5. Seismic activity occurs in six groups: 1.) Normal faulting outer rise events 2.) A shallow group of plate interface seismicity apparent at 25-35 km depth and 50-120 km distance to the trench with some variations between profiles. Along strike, the aftershocks occur largely within the zone of coseismic slip but extend similar to 50 km further north, and with predominantly shallowly dipping thrust mechanisms. Along dip, the events are either within the zone of coseismic slip, or downdip from it, depending on the coseismic slip model used. 3.) A third band of seismicity is observed further downdip at 40-50 km depth and further inland at 150-160 km trench perpendicular distance, with mostly shallow dipping (similar to 28 degrees) thrust focal mechanisms indicating rupture of the plate interface significantly downdip of the coseismic rupture, and presumably above the intersection of the continental Moho with the plate interface. 4.) A deep group of intermediate depth events between 80 and 120 km depth is present north of 36 degrees S. Within the Maule segment, a large portion of events during the inter-seismic phase originated from this depth range. 5.) The magmatic arc exhibits a small amount of crustal seismicity but does not appear to show significantly enhanced activity after the M-w 8.8 Maule 2010 earthquake. 6.) Pronounced crustal aftershock activity with mainly normal faulting mechanisms is found in the region of Pichilemu (similar to 34.5 degrees S). These crustal events occur in a similar to 30 km wide region with sharp inclined boundaries and oriented oblique to the trench. The best-located events describe a plane dipping to the southwest, consistent with one of the focal planes of the large normal-faulting aftershock (M-w = 6.9) on 11 March 2010. (C) 2011 Elsevier B.V. All rights reserved.