Isolating along-strike variations in the depth extent of shallow creep and fault locking on the northern Great Sumatran Fault
Isolating along-strike variations in the depth extent of shallow creep and fault locking on the northern Great Sumatran Fault
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DOI：
10.1029/2011jb008940
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发表时间：
2012-06
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通讯作者：
Takeo Ito;E. Gunawan;F. Kimata;T. Tabei;M. Simons;I. Meilano;Agustan;Y. Ohta;I. Nurdin;D. Sugiyanto
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文献类型：
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作者：
Takeo Ito;E. Gunawan;F. Kimata;T. Tabei;M. Simons;I. Meilano;Agustan;Y. Ohta;I. Nurdin;D. Sugiyanto
印度尼西亚的大苏门答腊断层系统是一个主要的右旋海沟平行系统，可分为几个部分，其中大部分在上个世纪破裂。这项研究的重点是断层系统的北方部分，其中包含一个200公里长的部分，至少170年没有经历过大地震。2005年，我们建立了亚齐的全球定位系统网络，用于跨越这一段的苏门答腊断层系统（AGNeSS）。AGNeSS观测到大位移，其中包括最近大型逆冲断层地震的显著震后变形以及由于大逆冲断层和走滑系统的持续弹性加载而引起的震间变形。我们参数化的位移，由于后滑的megahutch使用一个模型的基础上的速率和状态相关的摩擦形式主义。使用这种方法，我们能够从其他贡献分离后滑。我们删除预测变形，由于从观测后滑，并使用这些校正的时间序列来推断深度浅的seasonian蠕变和更深的锁定段的大Summartan断层。在该断裂段的北方，我们推断，地壳以2.0 ± 0.6厘米/年的速率向下蠕动至7.3 ± 4.8公里深处。在该段的西南部，我们估计锁定深度为14.8 ± 3.4 km，下倾滑动速率为1.6 ± 0.6 cm/年。这部分断层能够产生7.0级地震。
The Great Sumatran Fault system in Indonesia is a major right-lateral trench-parallel system that can be divided into several segments, most of which have ruptured within the last century. This study focuses on the northern portion of the fault system which contains a 200-km-long segment that has not experienced a major earthquake in at least 170 years. In 2005, we established the Aceh GPS Network for the Sumatran Fault System (AGNeSS) across this segment. AGNeSS observes large displacements which include significant postseismic deformation from recent large megathrust earthquakes as well as interseismic deformation due to continued elastic loading of both the megathrust and the strike slip system. We parameterize the displacements due to afterslip on the megathrust using a model based on a rate- and state-dependent friction formalism. Using this approach, we are able to separate afterslip from other contributions. We remove predicted deformation due to afterslip from the observations, and use these corrected time series to infer the depth of shallow aseismic creep and deeper locked segments for the Great Sumatran Fault. In the northern portion of this fault segment, we infer aseismic creep down to 7.3 ± 4.8 km depth at a rate of 2.0 ± 0.6 cm/year. In the southwestern portion of the segment, we estimate a locking depth of 14.8 ± 3.4 km with a downdip slip rate of 1.6 ± 0.6 cm/year. This portion of the fault is capable of producing a magnitude 7.0 earthquake.