How do subduction zones initiate, develop and end: Imaging the Reversal of Subduction in the Solomon Islands

板块构造是解释地震、火山、地壳变形以及地球表面运动的基本理论。然而，关于破坏性板块边界是如何开始、演化和结束的，人们知之甚少。这是板块构造的中心，因为板块运动的主要驱动力被认为是俯冲板块的引力。在所罗门群岛和巴布亚新几内亚，太平洋板块和澳大利亚板块正在汇合。在北部，一个俯冲带的生命周期即将结束，因为异常浮力的大洋板块正在停止俯冲。在圣克里斯托瓦尔海沟以南，一个新的俯冲带已经启动，以回应太平洋和澳大利亚板块的持续汇聚，使这里成为了解俯冲开始和停止的完美场所。在这项紧急建议中，我们将部署一年的地震仪，以记录7.1-7.6级之间的4次大地震序列的余震。这些来自全球各地的地震记录和其他记录将使我们能够高精度地圈定新旧俯冲板块的板块界面，并对深处的板块结构进行成像。新旧俯冲带的结构将阐明在深处发生的过程，这些过程正在改变该地区的力量平衡，以扭转俯冲的感觉。拟议中的实验将得到计划于2014年秋季部署的同时进行的研究的加强，其中包括日本同事进行的数百万磅的海底地震部署。组合后的阵列将使我们能够想象阻碍俯冲的太平洋板块，使我们能够调查板块阻止板块下降到地幔所必需的条件。因此，我们将能够理解俯冲是如何停止和开始的。

Plate tectonics is a fundamental theory for explaining earthquakes, volcanoes, crustal deformation and therefore the motion at the Earth's surface. However very little is known about how destructive plate boundaries initiate, evolve and end. This is central to plate tectonics, as it is thought that the dominant driving force of plate motions is the gravitational pull of subducting plates.In the Solomon Islands and Papua New Guinea, the Pacific and Australian plates are converging. In the north one subduction zone is nearing the end of its life cycle as anomalously buoyant oceanic plate is stalling subduction. To the south in the San Cristobal Trench, a new subduction zone has initiated in response to continued convergence of the Pacific and Australian plates, making this the perfect place to understand subduction initiation and cessation. In this urgency proposal we will deploy seismometers for 1 year to record aftershocks from sequence of 4 major earthquakes with magnitudes between 7.1-7.6. These recordings and other recordings of earthquakes from around the globe will allow us to delineate with high accuracy the plate interfaces of the new and old subducting slabs and image the slab structures at depth. The structure of the old and new subduction zones will illuminate the processes occurring at depth which are shifting the force balance in the region to reverse the sense of subduction.The proposed experiment will be enhanced by concurrent studies scheduled to be deployed in Fall of 2014, which includes a multimillion pound ocean bottom seismic deployment by colleagues in Japan. The combined array will allow us to image the Pacific plate which is stalling the subduction, allowing us to investigate what conditions are necessary for a plate to halt the descent of the slab into the mantle. Thus we will be able to understand how subduction stops and starts.