The Colima Deep Seismic Experiment: Imaging the Magmatic Root of Colima Volcano

世界上大部分的火山爆发都发生在广布的火山中心和汇聚的边缘。来自俯冲楔形的玄武岩岩浆被引导到相距数十或数百公里的火山，并演化成与穹隆生长、火山碎屑流和爆炸性喷发有关的富含二氧化硅的成分。几十年的地球化学研究已经勾勒出了一套控制海豚化学和空间演化的过程。这些想法在很大程度上依赖于地壳下部的过程，在地球物理学的投入有限的情况下发展起来，因为地壳深层很难用地震学、重力和/或电磁学来探测。科里马深部地震实验是首批针对深部地壳过程的实验之一，这些过程产生了离散的火山，并最终控制了喷发行为。PI将与墨西哥科里马大学火山观测站合作，在科里马火山附近安装和维护地震阵列18个月。天文台负责监测科里马火山，该火山正处于持续的喷发周期中，并监测整个科里马州的地震活动，该州在过去十年中发生了两次7.5级以上的地震。该项目将与格兰德和尼(EAR#0335782)的弧形规模网络一起进行生态部署，该网络恰好以科利马为中心。这一中间波段仪器阵列将比典型的火山监测阵列更宽，旨在优化深部地壳的地震层析成像和接收器功能。远程地震数据以及当地地壳和俯冲板的地震活动将用于绘制科里马火山下面的温度和熔融条件图。这一结果将在科利马杂岩的现有地球化学模型的背景下加以解释，以解决两个主要问题。(I)弧形火山的位置和寿命主要是受地幔楔体的底辟作用控制，还是受地壳深部条件和莫霍面地形的影响？(2)地壳底部的岩浆蓄积和下地壳的岩浆储存在控制俯冲玄武岩演化为更多的硅弧型火山岩方面起到了什么相对作用？这些问题虽然非常适合科利马火山，但对所有弧形火山都有影响。这个项目是由国际部的美洲项目共同发起的。

ABSTRACTMost of the world's explosive volcanism occurs at widely-spaced volcanic centersalong convergent margins. Basaltic magmas from the subduction wedge arechanneled to volcanoes separated by tens or hundreds of kilometers and evolveinto silica-rich compositions associated with dome growth, pyroclastic flowsand explosive eruptions. Decades of geochemical research have outlined a suiteof processes which control the chemical and spatial evolution of thesevolcanoes. These ideas, which rely heavily on processes in the lowermost crust,have evolved with limited input from geophysics because the deep crust has beendifficult to probe with seismics, gravity, and/or electromagnetics. The ColimaDeep Seismic Experiment is one of the first to target the deep crustalprocesses which create discrete volcanoes and ultimately control eruptivebehavior. In conjunction with the Observatorio Vulcanologico of ColimaUniversity in Mexico, the PI will install and maintain a seismic array for 18months in the vicinity of Colima Volcano. The Observatorio is responsible formonitoring Colima Volcano, which is in the midst of an on-going eruption cycle,and seismicity throughout the state of Colima which has had two earthquakesgreater than magnitude 7.5 in the last ten years. This project will beco-deployed with the arc-scale network of Grand and Ni (EAR #0335782) which isserendipitously centered on Colima. This array of intermediate-band instrumentswill be wider than a typical volcano monitoring array and is designed tooptimize seismic tomography and receiver functions of the deep crust.Teleseismic data, together with seismicity in the local crust and subductingslab, will be used to map the temperature and melt conditions beneath ColimaVolcano. The results will be interpreted in the context of existing geochemicalmodels for the Colima complex to address two primary questions. (i) Is thelocation and longevity of an arc volcano governed principally by diapirism inthe mantle wedge or by deep crustal conditions and Moho topography? (ii) Whatare the relative roles of magma ponding at the base of the crust and magmastorage in the lower crust in controlling the evolution of subduction basaltsinto more silicic arc volcanics? These questions, though ideally suited toColima, have implications at all arc volcanoes. This project is co-sponsored bythe Americas Program in the International Division.