Seismicity and Fault Structure of Oceanic Detachment Faults

海洋扩张中心的板块裂谷是通过断层和岩浆注入的结合而发生的，这两者都减轻了与全球构造力相关的累积应力。有时断层可能占主导地位，导致沿单一平面持续滑动超过一百万年。 Seafloor formed during such periods of 'detachment faulting' differs from the typical, linear volcanic hills that are ubiquitous on the seafloor.相反，随着最初深部岩石因跨断层的相对运动而被揭开，形成了具有长达几公里海底起伏的穹丘特征。 This study aims to show how detachment faults behave seismically- where small earthquakes occur with depth along the fault and how that activity varies laterally. New insights gained in this study could be applicable to other regions where extensional tectonic stress and magmatism occur, such as parts of the U.S. Basin and Range province. This study is jointly supported by the Marine Geology and Geophysics Program and the International Science and Engineering section of NSF.Analysis of microseismicity data recorded during 6-month deployments of ocean bottom seismometers at 13°N and 26°N on the Mid-Atlantic Ridge will be conducted in order to elucidate fault activity at young oceanic core complexes.北纬 13° 的工作是更广泛的英法美合作项目的组成部分； 26°N 的工作重点是规模介于先前研究的事件之间的地震；新结果将首次详细关注浅于 3 公里的地壳。将比较这两个拥有海洋核心复合体的区域的地震活动模式。地震分布的记录，以及可能的一些震源机制，旨在评估脱离断层在 3D 中的表现以及断层强度和空间/时间演化方面的影响。

Plate rifting at oceanic spreading centers occurs through a combination of faulting and injection of magma, both of which relieve built-up stress associated with global tectonic forces. At times faulting can dominate, leading to sustained slip along a single plane for over a million years. Seafloor formed during such periods of 'detachment faulting' differs from the typical, linear volcanic hills that are ubiquitous on the seafloor. Instead domal features, with up to a few km seafloor relief, develop as initially deep rock is unroofed by relative motion across the fault. This study aims to show how detachment faults behave seismically- where small earthquakes occur with depth along the fault and how that activity varies laterally. New insights gained in this study could be applicable to other regions where extensional tectonic stress and magmatism occur, such as parts of the U.S. Basin and Range province. This study is jointly supported by the Marine Geology and Geophysics Program and the International Science and Engineering section of NSF.Analysis of microseismicity data recorded during 6-month deployments of ocean bottom seismometers at 13°N and 26°N on the Mid-Atlantic Ridge will be conducted in order to elucidate fault activity at young oceanic core complexes. The 13°N work is one component of broader UK-French-US collaborative project; the 26°N effort focuses on earthquakes intermediate in size between events that were previously studied; new results will focus in detail on crust shallower than 3 km for the first time. The seismicity patterns of these two areas, that both host oceanic core complexes, will be compared. Documentation of the distribution of earthquakes, and possibly some focal mechanisms, aims to assess how detachment faults behave in 3-D and what the implications might be in terms of fault strength and spatial/temporal evolution.