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

0437181 LevinThis美洲计划奖将有助于支持Alissa Henza博士论文的主要部分，在罗格斯大学的Vadim Levin博士的监督下，并与Costarricense de Electricidad研究所的科学家团队合作，该研究所的Guillermo阿尔瓦拉多博士和哥斯达黎加大学领导。 研究人员打算研究地球地幔区的工作过程，这些过程控制着板块构造、火山弧，并强烈影响着大陆的增生。在哥斯达黎加的众多火山中，只有一座被称为塞罗梅塞德斯的火山，已知其产生的熔岩中含有地壳下的岩石包裹体。这种地幔结核或捕虏体的发现，在与俯冲有关的活火山活动区是不寻常的。在塞洛梅塞德斯发现的地幔结核表明了该地点的特殊条件。研究人员打算在发现捕虏体的地方附近部署一个小型便携式宽带地震传感器阵列，为期15个月。 根据这一合作努力收集的数据进行研究的主要目的是：a）捕虏体是来自覆盖板块还是来自板上地幔楔？以及B）是否存在以相干岩石组构为特征的深度区域;捕虏体是否来自其中之一？ 地震观测活动将在靠近阿纳尔和米拉瓦列火山的地区进行，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，让哥斯达黎加研究人员参与，他们的主要任务和专门知识都在这些领域。

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.