Collaborative Research: Seismic and Geodetic Constraints on the Evolution of Magmatic and Eruptive Processes at Arenal and Irazu Volcanos, Costa Rica

本提案旨在研究哥斯达黎加几个处于火山循环不同阶段的安山岩层状火山的地震和大地测量行为，以便更好地了解活动岩浆系统的性质和动力学，并改善火山灾害的缓解。1995年，在哥斯达黎加的阿雷纳尔火山建立了两个永久性全球定位系统（GPS）接收器和五个配备宽带地震传感器和电子倾斜仪的台站。这些观测是对活火山进行的为数不多的宽带地震记录和连续高精度大地测量之一。对GPS数据的初步解释表明，一个相对较浅的岩浆储层正在枯竭，岩浆以岩脉或岩壁的形式在较浅的水平注入。通过扩大GPS测量的空间分辨率和分析Arenal的谐波震颤和峰顶爆炸的地震记录，将获得该岩浆系统的几何形状和行为的定量约束。在Irazu、Turrialba和Rincon de la Vieja的小型GPS网络和地震观测（包括在Irazu的2个永久性GPS站）将允许在两次喷发周期之间描述与这些火山相关的地表变形。目前不活跃火山的基线变形数据非常罕见，但对于评估火山危害和了解大喷发周期较长时间尺度上的岩浆过程可能非常有价值。*＊*

9614687 Schwartz This proposal is to investigate the seismic and geodetic behavior of several andesitic stratovolcanoes in Costa Rica that are in different stages of their volcanic cycles in order to better understand the properties and dynamics of active magmatic systems and to improve volcanic hazard mitigation. In 1995, two permanent Global Positioning System (GPS) receivers and five stations equipped with broadband seismic sensors and electronic tiltmeters were established on Arenal Volcano, Costa Rica. These observations are among the first few broadband seismic recordings and continuous, high precision, geodetic measurements made on an active volcano. Preliminary interpretation of the GPS data suggest ongoing depletion of a relatively shallow magma reservoir and magmatic injection at shallower levels in the form of dikes or sills. Quantitative constraints on the geometry and behavior of this magmatic system will be obtained by expanding spatial resolution of the GPS measurements and analyzing the seismic recordings of the harmonic tremor and summit explosions at Arenal. Modest GPS networks and seismic observations on Irazu, Turrialba and Rincon de la Vieja (including 2 permanent GPS stations on Irazu) will allow the characterization of surface deformation associated with these volcanoes in between eruptive cycles. Baseline deformation data at presently inactive volcanoes is quite rare, but potentially very valuable for evaluating volcanic hazards and for understanding magmatic processes on the longer time scale of major eruptive cycles. ***