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，对于破坏性板块边界如何开始、演化和结束，我们所知甚少。这是板块构造学的核心，因为人们认为板块运动的主要驱动力是俯冲板块的引力。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交汇。在北部，一个俯冲带正接近其生命周期的结束，因为异常浮力的大洋板块正在阻止俯冲。在圣克里斯托瓦尔海沟的南部，由于太平洋板块和澳大利亚板块的持续融合，一个新的俯冲带开始形成，这使得这里成为了解俯冲开始和停止的完美地点。在这项紧急提案中，我们将部署地震仪，为期一年，记录震级在7.1-7.6级之间的4次大地震的余震。这些记录和其他来自世界各地的地震记录将使我们能够高精度地描绘新旧俯冲板块的板块界面，并对板块结构进行深度成像。新旧俯冲带的构造将阐明发生在深部的过程，这些过程正在改变该地区的力平衡，以扭转俯冲感。拟议中的实验将在2014年秋季同时进行的研究中得到加强，其中包括由日本同事进行的价值数百万英镑的海底地震部署。联合阵列将使我们能够对阻止俯冲的太平洋板块进行成像，使我们能够研究一个板块停止其向地幔下降所必需的条件。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.