A Seismic Study of the Taiwan Orogen

题目：台湾造山带的地震研究作者：陈王平，美国伊利诺伊大学地质学系和中美洲地震中心，伊利诺伊大学厄巴那分校，伊利诺伊大学，伊利诺斯州，伊利诺斯州61801这是一篇关于台湾造山带的地震研究，台湾造山带是近20年来国际上研究的一个重要的活动碰撞带案例。自1999年破坏性的集集地震序列以来，台湾及其周边地区的地震活动显著增加。最先进的仪器阵列很好地记录了数百次大到中等规模的地震，为研究活跃的弧-陆碰撞提供了高分辨率数据。我们计划研究大约300次地震，包括精确确定震中、震源深度、断层平面解和地震矩，以解决主动碰撞中的一些关键问题。碰撞带的年轻和快速收敛特别有利于解决：1)如果空间变化反映碰撞的时间进展；2)如果在碰撞的早期阶段已经存在的伸展构造的重新激活是重要的。我们将集中讨论这些主题，并在从各种来源收集的地质和地球物理信息的背景下进行解释。此外，我们将在西菲律宾海内部研究缝合带以东的扩散变形。最近的海洋数据显示，菲律宾海碰撞边缘的年龄惊人地老（早白垩纪）。这个区域位于海洋岩石圈之下，通常被认为具有很强的机械强度，因此充当碰撞的驱动边缘。这项提议的工作将限制碰撞海洋岩石圈最强烈部分的厚度，并可能为旧海底异常浅的深度提供线索。

Abstract for proposal EAR0106786 (PH # 9x)Title: A Seismic Study of the Taiwan OrogenPI's: Wang-Ping Chen, Department of Geology and Mid-America Earthquake Center, University of Illinois, Urbana, IL 61801This is a seismic study of the Taiwan orogen, an important case of active collision zone that has been a focus of international research for the last 20 years. Since the devastating Chi-Chi earthquake sequence of 1999, seismicity increased remarkably in and around Taiwan. Hundreds of large- to moderate-sized earthquakes have been well recorded by arrays of state-of-the-art instruments, providing high-resolution data to investigate active arc-continent collision.We plan to study about 300 earthquakes, including precise determinations of epicenters, focal depths, fault plane solutions, and seismic moments, in order to address some key questions in active collision. The young age and fast convergence of the collision zone are particularly favorable for resolving: 1) if spatial variations reflect time-progression of collision; and 2) if reactivation of pre-existing, extensional structures is important in the early stages of collision. We will focus on these topics and cast our interpretation in the context of geological and geophysical information gathered from various sources.In addition, we will study diffuse deformation to the east of the suture zone, in the interior of the western Philippine Sea. Recent marine data showed a surprisingly old age (early Cretaceous) for the colliding edge of the Philippine Sea. This region, underlain by oceanic lithosphere, is often assumed to be mechanically strong, thus behaving as the driving edge of the collision. The proposed work will constrain the thickness of the strongest part of the colliding oceanic lithosphere, and potentially provide clues to the anomalously shallow depth of the old sea floor.