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

0437181列文这个美洲项目奖将帮助支持Alissa Henza博士论文的主要部分，在罗格斯大学的Vadim Levin博士的指导下，并与由该研究所的Guillermo Alvarado博士领导的哥斯达黎加电力研究所和哥斯达黎加大学的科学家团队合作。研究人员打算研究地幔带的作用过程，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，只有一座名为塞罗·梅塞德斯的火山产生了熔岩，熔岩中含有地壳下的岩石内含物。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地区是不寻常的。在塞罗·梅塞德斯发现的地幔结核表明这个地点的特殊条件。研究人员打算在发现捕虏体的地方附近部署一组小型便携式宽带地震传感器，为期15个月。基于这次合作收集的数据，研究的主要目的将是：a)捕虏体是来自上覆板块还是来自上地幔楔？b)是否存在以连续岩组构为特征的深度区域；捕虏体来自其中一个吗？地震观测站活动将在靠近Arenal和Miravalles火山的地区开展，这两个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之外，该项目的更广泛影响还将扩大到火山风险评估和减灾，因为哥斯达黎加的研究人员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.