Probing the Multiscale Nature of Crustal Magma Transport

Leif Karlstrom博士已获得NSF地球科学博士后奖学金，在斯坦福大学开展研究和教育计划。他将通过对火山震颤的建模和对弧尺度喷发模式的统计推断，在两个不同尺度上研究地壳中的岩浆输送过程。地震工作旨在确定火山爆发期间地震活动起源的可用机制，并将利用耦合流体流动和弹性动力学数值模型研究不同喷发类型的长周期地震特征。这项工作的更大规模的方面将测试模型的岩浆铅垂与第四纪火山喷发的瀑布弧。网络推理技术和贝叶斯统计将被应用到一个新的汇编数据集最近的火山活动在整个瀑布。本研究的目的是测试在何种程度上控制岩浆运输的动态内部组织与外部forcing（冰川作用，空间可变的构造应力）。岩浆运输是相关的了解地球历史和火山-人类的相互作用，但它在很大程度上是无法直接观察。因此，产生幕式火山作用的岩浆上升和冷却的机制受到很大的限制。这项工作通过模拟火山爆发期间辐射地震波的模式来探测火山的深层结构，并使用统计推断技术来探测整个喀斯喀特火山弧的岩浆管道结构。这些研究提出了一个普遍的问题：理论模型在多大程度上能够代表或预测间接的、遥远的观测结果？这一问题对综合模型和数据以解释地质记录和评估火山灾害的程度具有重要意义。与该项目相关的教育活动包括带领一次拉森国家公园实地考察，并在斯坦福大学共同教授一门物理火山学课程。

Dr. Leif Karlstrom has been granted an NSF Earth Sciences postdoctoral fellowship to carry out a research and education plan at Stanford University. He will investigate magma transport processes in the crust on two different scales through modeling of volcanic tremor and statistical inference of arc-scale eruption patterns. The tremor work aims to identify available mechanisms for the origin of seismicity during volcanic eruptions, and will examine long period seismic signatures of different eruption styles with a coupled fluid flow and elastodynamic numerical model. The larger scale aspect of this work will test models of magmatic plumbing with Quaternary eruptions in the Cascades arc. Network inference techniques and Bayesian statistics will be applied to a newly compiled dataset of recent volcanism throughout the Cascades. The goal of this study is to test for the degree to which magma transport is controlled by dynamic internal organization versus external forcing (glaciation, spatially variable tectonic stresses).Magma transport is relevant both for understanding Earth history and volcano-human interactions, but it is largely inaccessible to direct observation. As a result, the mechanics of rising and cooling magmas that generate episodic volcanism are poorly constrained. This work probes the deep structure of volcanoes by modeling patterns of radiated seismic waves during eruptions, and using statistical inference techniques to probe the structure of magma plumbing throughout the Cascades volcanic arc. These studies ask the general question: to what extent can theoretical models represent or predict indirect, remote observations? This question has important implications for the degree to which models and data can be synthesized to interpret the geologic record and assess volcanic hazards. Educational activities associated with this project include leading a field trip to Lassen National Park and co-teaching a course on physical volcanology at Stanford.