Astudillo-Sotomayor Luis, Jara-Muñoz Julius, Melnick Daniel, Cortés-Aranda Joaquín, Tassara Andrés, Strecker Manfred R
Millennium Nucleus the Seismic Cycle Along Subduction Zones, Valdivia, Chile.
Departamento de Ciencias de la Tierra, Universidad de Concepción, Concepción, Chile.
Sci Rep. 2021 Mar 16;11(1):5970. doi: 10.1038/s41598-021-85036-5.
In active tectonic settings dominated by strike-slip kinematics, slip partitioning across subparallel faults is a common feature; therefore, assessing the degree of partitioning and strain localization is paramount for seismic hazard assessments. Here, we estimate a slip rate of 18.8 ± 2.0 mm/year over the past 9.0 ± 0.1 ka for a single strand of the Liquiñe-Ofqui Fault System, which straddles the Main Cordillera in Southern Chile. This Holocene rate accounts for ~ 82% of the trench-parallel component of oblique plate convergence and is similar to million-year estimates integrated over the entire fault system. Our results imply that strain localizes on a single fault at millennial time scale but over longer time scales strain localization is not sustained. The fast millennial slip rate in the absence of historical Mw > 6.5 earthquakes along the Liquiñe-Ofqui Fault System implies either a component of aseismic slip or Mw ~ 7 earthquakes involving multi-trace ruptures and > 150-year repeat times. Our results have implications for the understanding of strike-slip fault system dynamics within volcanic arcs and seismic hazard assessments.
在以走滑运动学为主导的活动构造环境中，跨近平行断层的滑动分配是一个常见特征；因此，评估分配程度和应变局部化对于地震危险性评估至关重要。在这里，我们估计了利基内-奥夫基断层系统单条断层在过去9.0±0.1千年期间的滑动速率为18.8±2.0毫米/年，该断层系统横跨智利南部的主科迪勒拉山脉。这一全新世速率约占斜向板块汇聚的海沟平行分量的82%，并且与整个断层系统在百万年时间尺度上的估计值相似。我们的结果表明，应变在千年时间尺度上集中在单一断层上，但在更长的时间尺度上，应变局部化并不持续。在利基内-奥夫基断层系统沿线没有发生历史Mw>6.5级地震的情况下，快速的千年滑动速率意味着存在无震滑动成分，或者存在Mw~7级地震，涉及多条断层破裂且重复间隔时间超过150年。我们的结果对于理解火山弧内走滑断层系统动力学以及地震危险性评估具有重要意义。
