U.S.-Costa Rica Dissertation Research: Operation of Seismic Array at Cerro Mercedes, Costa Rica

0437181莱文这个美洲项目奖将帮助支持艾丽莎·亨扎博士论文的主要部分，在罗格斯大学的瓦迪姆·莱文博士的指导下，并与Costarricense de Electricada研究所和哥斯达黎加大学的Guillermo Alvarado博士领导的科学家团队合作。研究人员打算研究在地球地幔地带工作的过程，这些过程对板块构造、火山弧施加控制，并强烈影响大陆的吸积。在哥斯达黎加的众多火山中，已知只有一座名为Cerro Mercedes的火山产生了熔岩，其中含有地壳下的岩石。在与俯冲有关的活火山活动地区，发现这样的地幔结核或捕虏体是不寻常的。在Cerro Mercedes发现的地幔结核表明了这个地点的特殊条件。研究人员打算在发现捕虏体的地点附近部署一小批便携式宽带地震传感器，持续15个月。根据这次合作所收集的数据进行的研究的主要目的是：a)捕虏体是来自上覆板块还是来自上地幔楔形？B)是否存在以一致岩石组构为特征的深部区域；捕虏体是否来自其中之一？地震观测站活动将在靠近Arenal和Miravalles火山的地区进行，这两座火山是哥斯达黎加火山灾害的主要来源。因此，除了科学兴趣和学生培训外，该项目的更广泛影响将扩大到火山风险评估和减灾，让主要任务和专门知识在这些领域的哥斯达黎加研究人员参与进来。

0437181 LevinThis Americas Program award will help to support the major part of the PhD thesis of Alissa Henza, under the supervision of Dr. Vadim Levin of Rutgers University and in collaboration with a team of scientists from the Instituto Costarricense de Electricidad, headed by Dr. Guillermo Alvarado of that institute and also at the University of Costa Rica. The researchers intend to study processes at work on the Earth's mantle zone that exert control over plate tectonics, volcanic arcs, and strongly influence the accretion of continents. Among numerous volcanoes of Costa Rica only one, called Cerro Mercedes, is known to have produced lavas that carry within them inclusions of rock from beneath the crust. Finds of such mantle nodules, or xenoliths, are unusual in areas of active volcanism associated with subduction. A discovery of mantle nodules at Cerro Mercedes suggests special conditions at this site. The researchers intend to deploy a small array of portable broadband seismic sensors in the immediate vicinity of the locality where xenoliths were found, for the duration of 15 months. Primary aims of the study based on the data collected by this cooperative effort will be: a) Are xenoliths derived from the overriding plate or from the supraslab mantle wedge? and b) Are there depth regions characterized by coherent rock fabric; do xenoliths come from one of them? The seismological observatory campaign will be carried out in an area proximate to Arenal and Miravalles volcanoes that are major sources of volcanic hazards in Costa Rica. Thus, in addition to the scientific interest and the student training, the project's broader impacts will extend to volcanic risk assessment and hazard mitigation by involving Costa Rican researchers whose primary tasks and expertise reside in those areas.