Mantle Deformation From Seismic Anisotropy

9304560白银这个PASSCAL实地项目将研究南美洲高原的深层结构，这是世界上最高和最大的高原之一，平均海拔近4公里，地壳厚度65公里，面积超过600,000平方公里，位于秘鲁南部、玻利维亚西部和智利北部的交界处。这项调查将检验这个高原的形成理论和总体上的造山理论。研究人员将在该地区部署20个PASSCAL地震台，以确定地壳厚度、下伏地幔楔体的结构以及横波分裂的变化，横波分裂是岩石组构和变形历史的指示。计划与法国ORSTOM计划和南美科学家在部署和分析方面进行合作。这个活跃的地震区，大洋板块俯冲到大陆之下，类似于美国太平洋西北构造体制。这项研究是国家减少地震灾害计划的一部分。***

9304560 Silver This PASSCAL field project will examine the deep structure of the South American Altiplano, one of the world's highest and largest plateaus with an average elevation of nearly 4 km, a crustal thickness of 65 km and area of over 600,000 square km at the intersection of southern Peru, western Bolivia, and northern Chile. The investigation will test theories of formation of this plateau and of mountain-building in general. The investigators will deploy 20 PASSCAL seismic stations across the region to determine variations in crustal thickness, structure of the underlying mantle wedge, and shear wave splitting which is an indication of the fabric and distortion history of the rock. A collaboration in deployment and analysis is planned with the French ORSTOM Program and with South American scientists. This active seismic area, where the oceanic plate is subducted under the continent, is an analog to the U.S. Pacific Northwest tectonic regime. This research is a component of the National Earthquake Hazard Reduction Program. ***