Coseismic and postseismic slip associated with the 2010 Maule Earthquake, Chile: Characterizing the Arauco Peninsula barrier effect
Coseismic and postseismic slip associated with the 2010 Maule Earthquake, Chile: Characterizing the Arauco Peninsula barrier effect
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DOI：
10.1002/jgrb.50207
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发表时间：
2013-06-01
影响因子：
3.9
通讯作者：
Socquet, Anne
中科院分区：
文献类型：
--
作者：
Lin, Yu-nung Nina;Sladen, Anthony;Socquet, Anne
对2010年智利中南部发生的8.8级毛勒地震的同震和震后形变的观测，限制了一个主要俯冲巨型逆冲的摩擦性质的空间异质性，以及它们如何影响地震破裂和震后效应。我们发现，大部分同震滑动发生在一个长约460公里、宽约100公里、深度在15至40公里之间的细长斑块内。我们推断了三个主要的余滑斑块：一个沿着主同震斑块的走向和下倾向北延伸，深度在40-60公里之间；另外两个位于同震斑块的南北两端。阿劳科半岛近海的南部补丁是唯一显示出深度小于20公里的可解决后滑浅层的地方。据估计，在震后1.3年内，与震后滑动有关的滑动潜力相当于同震产生的滑动潜力的20%-30%。我们对巨型逆冲摩擦性质的估计表明，阿劳科半岛地区具有正的但相对较低的(a-b)sigma(N)值(0.01，类似于0.22 Mpa)，这将允许动态破裂扩展到该速率强化区和余滑。考虑到该地区仅有的适度的速率强化巨型金锈摩擦，屏障效应可能归因于其相对较大的速率强化斑块。自1835年最后一次大地震以来，阿劳科半岛的同震和震后隆起超过了震间沉降，这表明同震和震后变形在弧前造成了一些永久性应变。
Observations of coseismic and postseismic deformation associated with the 2010 Mw=8.8 Maule earthquake in south-central Chile provide constraints on the spatial heterogeneities of frictional properties on a major subduction megathrust and how they have influenced the seismic rupture and postseismic effects. We find that the bulk of coseismic slip occurs within a single elongated patch approximately 460 km long and 100 km wide between the depths of 15 and 40km. We infer three major patches of afterslip: one extends northward along strike and downdip of the major coseismic patch between 40 and 60km depth; the other two bound the northern and southern ends of the coseismic patch. The southern patch offshore of the Arauco Peninsula is the only place showing resolvable afterslip shallower than 20 km depth. Estimated slip potency associated with postseismic slip in the 1.3years following the earthquake amounts to 20-30% of that generated coseismically. Our estimates of the megathrust frictional properties show that the Arauco Peninsula area has positive but relatively low (a-b)sigma(n) values (0.01 similar to 0.22MPa), that would have allowed dynamic rupture propagation into this rate-strengthening area and afterslip. Given the only modestly rate-strengthening megathrust friction in this region, the barrier effect may be attributed to its relatively large size of the rate-strengthening patch. Coseismic and postseismic uplift of the Arauco Peninsula exceeds interseismic subsidence since the time of the last major earthquake in 1835, suggesting that coseismic and postseismic deformation has resulted in some permanent strain in the forearc.