Active upper plate thrust faulting in regions of low plate interface coupling, repeated slow slip events, and coastal uplift: Example from the Hikurangi Margin, New Zealand
Active upper plate thrust faulting in regions of low plate interface coupling, repeated slow slip events, and coastal uplift: Example from the Hikurangi Margin, New Zealand
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低板块界面耦合区域的活跃上板块逆冲断层、重复的慢滑动事件和海岸隆起：新西兰希库朗吉边缘的例子
DOI：
10.1029/2010gc003326
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发表时间：
2011
期刊：
影响因子：
3.7
通讯作者：
P. Barnes
中科院分区：
文献类型：
--
作者：
J. Mountjoy;P. Barnes
收缩弧前断层和变形是许多俯冲系统的特征。定义了希库朗吉边缘上沿着约250 km活动的上板块无序逆冲断层的三维几何形状和位移速率，使我们能够根据震间耦合估计和慢滑事件分布（两者均由GPS测量建模）来研究弧前变形与俯冲界面之间的关系。这些弧前中期结构包括向海的外陆架拉克伦和阿里尔断层，垂直分离速率高达5毫米/年，以及其他几个主要的内陆架断层，速率高达3.8毫米/年，与全新世海岸隆起速率相当。地震反射成像和几何投影的这些故障在深度表明，他们从该地区的板块界面张开的大地测量反演地震间的耦合和慢滑事件表明，板块边界经历了地震滑动。这一观察结果可能表明：（1）板块界面上的摩擦特性和地震间耦合与中前弧内的活动展曲断层变形无关，或（2）活动展曲断层反映了与较高剪切应力或板块界面与上覆板块的相对屈服强度相关的长期机械耦合，目前的震间耦合模式在20 ka的地质时间尺度上可能不会持续。我们比较了北方希库朗吉和哥斯达黎加边缘的结构和过程，发现这些俯冲系统之间的相似之处和显着差异。
Contractional fore‐arc faulting and deformation is a characteristic feature of many subduction systems. Definition of the three‐dimensional geometry and displacement rates of active, upper plate, out‐of‐sequence thrust faults along ∼250 km of the upper Hikurangi Margin enables us to examine the relationship between fore‐arc deformation and the subduction interface in light of interseismic coupling estimates and distribution of slow slip events, both modeled from GPS measurements. These mid‐fore‐arc structures include the seaward vergent, outer shelf Lachlan and Ariel faults, with vertical separation rates up to 5 mm/yr, and several other major inner shelf faults with rates that are up to 3.8 mm/yr and comparable with Holocene coastal uplift rates. Seismic reflection imaging and geometric projection of these faults at depth indicate that they splay from the region of the plate interface where geodetic inversions for interseismic coupling and slow slip events suggest that the plate boundary undergoes aseismic slip. This observation may indicate either (1) that frictional properties and interseismic coupling on the plate interface are independent and unrelated to the active splay fault deformation in the inner‐middle fore arc or (2) that the active splay faulting reflects long‐term mechanical coupling related to higher shear stress, or the relative yield strength of the plate interface to the overriding plate, and that the current pattern of interseismic coupling may not be persistent over geological time scales of 20 ka. We compare structure and processes on the northern Hikurangi and Costa Rican margins and find similarities and significant differences astride these subduction systems.