The 2007 M7.7 Tocopilla northern Chile earthquake sequence: Implications for along-strike and downdip rupture segmentation and megathrust frictional behavior
The 2007 M7.7 Tocopilla northern Chile earthquake sequence: Implications for along-strike and downdip rupture segmentation and megathrust frictional behavior
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2007 年智利北部 M7.7 托科皮拉地震序列：对沿走向和下倾破裂分段和巨型逆冲摩擦行为的影响
DOI：
10.1029/2011jb009030
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发表时间：
2012
影响因子：
--
通讯作者：
J. Vilotte
中科院分区：
文献类型：
--
作者：
B. Schurr;G. Asch;M. Rosenau;Rongjiang Wang;O. Oncken;S. Barrientos;P. Salazar;J. Vilotte
[1]2007年，智利北部地震空区内的托科皮拉镇附近发生了7.7级地震。主震滑移是由同震面形变引起的，深度范围为30-55公里。我们在主震前六个月和主震后一周内重新定位了∼1100事件。余震活动首先与主震滑移一致，然后向梅吉洛内斯半岛以西和西北部近海扩散。对38次余震的波形模拟揭示了大多数与主震相似的震源机制。然而，少数事件似乎发生在上板块，其中一些具有伸展机制。将托科皮拉余震与邻近的1995年安托法加斯塔地震后的余震并列在一起，在MP中心的EW轴上产生了惊人的对称性。事件似乎绕过了国会议员，可能是因为那里的莫霍面较浅。我们认为，智利北部孕震耦合带在下倾方向的摩擦行为由不稳定变为基本有条件的稳定。对于这两个地震序列，余震在条件稳定区聚集，而最大震间滑动差和同震滑动出现在不稳定区。不稳定区域和有条件稳定区域之间的边界平行于海岸线。我们在智利和秘鲁的其他地震中发现了类似的分段，其中近海分段在8级大地震中破裂，陆上分段在较小的8级地震中破裂。利用临界锥度分析，我们证明了界面上不同的滑移行为与弧前楔形解剖之间的因果关系，这可以归因于摩擦率依赖的空间变化。
[1] In 2007 a M7.7 earthquake occurred near the town of Tocopilla within the northern Chile seismic gap. Main shock slip, derived from coseismic surface deformation, was confined to the depth range between 30 and 55 km. We relocated ∼1100 events during six months before and one week after the main shock. Aftershock seismicity is first congruent to the main shock slip and then it spreads offshore west and northwest of Mejillones Peninsula (MP). Waveform modeling for 38 aftershocks reveals source mechanisms that are in the majority similar to the main shock. However, a few events appear to occur in the upper plate, some with extensional mechanisms. Juxtaposing the Tocopilla aftershocks with those following the neighboring 1995 Antofagasta earthquake produces a striking symmetry across an EW axis in the center of MP. Events seem to skirt around MP, probably due to a shallower Moho there. We suggest that the seismogenic coupling zone in northern Chile changes its frictional behavior in the downdip direction from unstable to mostly conditionally stable. For both earthquake sequences, aftershocks agglomerate in the conditionally stable region, whereas maximum inter-seismic slip deficit and co-seismic slip occurs in the unstable region. The boundary between the unstable and conditionally stable zones parallels the coastline. We identify a similar segmentation for other earthquakes in Chile and Peru, where the offshore segments break in great M > 8 earthquakes, and the onshore segments in smaller M < 8 earthquakes. Using critical taper analysis, we demonstrate a causal relationship between varying slip behavior on the interface and forearc wedge anatomy that can be attributed to spatial variations in the rate-dependency of friction.
影响因子：
18.3
作者：
Lorito, S.;Romano, F.;Piatanesi, A.
通讯作者：
Piatanesi, A.
智利北部俯冲纳斯卡岩石圈的几何形状和厚度的高分辨率图像
影响因子：
--
作者：
Sodoudi F;Yuan X;Asch G;Kind R.
通讯作者：
Kind R.
影响因子：
2.8
作者：
S. Peyrat;R. Madariaga;E. Buforn;J. Campos;G. Asch;J. Vilotte
通讯作者：
S. Peyrat;R. Madariaga;E. Buforn;J. Campos;G. Asch;J. Vilotte