COLLABORATIVE RESEARCH: Geodetic measurements and mechanical models of the volcano deformation cycle

阿拉斯加的奥克莫克火山似乎每十年左右喷发一次，最近一次是在1997年，另一次是在2008年。利用现代方法对其活动进行监测，形成了丰富的观测数据集。研究人员正在开发一种地球物理模型，以解释大多数观测到的活动的时间和地点。这项研究的新信息将直接关系到理解奥克莫克火山和其他类似火山造成的随时间变化的火山危害，这些火山位于频繁使用的北太平洋空中交通走廊下方。同样类型的模型应该适用于其他表现出周期性活动的火山，如阿拉斯加的韦斯特达尔火山或冰岛的赫克拉火山。Okmok是进行这种实验的一个极好的天然实验室，因为已经使用大地测量和地震手段监测了一个完整的变形周期。利用这些丰富的观测数据集和正式的数值模拟协议，研究人员正在研究Okmok火山，以解决以下问题：(1)Okmok内部的物质性质分布如何？(2)非弹性流变如何改变变形场的时间演化？(3)深层材料特性如何影响地表观测到的变形？(4)描述岩浆库的模型参数的不确定性是什么？脉冲响应流变实验将提高对火山变形周期的认识。具体而言，该研究项目将检验四个假设：(1)1997年火山喷发后的变形在2008年火山喷发前没有达到稳定状态。(2)粘弹性应力松弛对喷发前后观测到的瞬态变形有贡献。(3)岩浆房外壳的有效黏度比周围地壳小几个数量级。1997年喷发时从A锥喷出的熔岩流产生了一个应力场，有利于岩脉从岩浆房向d锥传播。研究结果将发表在国际同行评议的文献上。来自科学，技术，工程和数学（STEM）中代表性不足的群体的研究生将在地震学，大地测量学和火山学这三个学科交叉的地球物理研究领域接受培训。建模协议和方法将在操作层面上在科学界传播。研究者Masterlark是一名来自EPSCoR实验项目办公室资助的机构的初级教员，他将提供一门关于如何将有限元方法应用于火山变形的短期课程。特别鼓励来自代表性不足群体的申请人参加。该项目将加强美国地质调查局的调查人员和科学家之间的合作

Okmok volcano in Alaska appears to erupt every decade or so, most recently in 1997 and again in 2008. Its activity has been monitored using modern methods, forming a rich observational data set. The investigators are developing a geophysical model that should explain the timing and location of most of the observed activity. The new information from this study will be directly relevant to understanding time-dependent volcanic hazard posed by Okmok and other, similar volcanoes lying beneath the heavily-used north Pacific air traffic corridors. The same type of model should be applicable to other volcanoes displaying cyclic activity, such as Westdahl in Alaska or Hekla in Iceland. Okmok is an excellent natural laboratory for such an experiment because a complete cycle of deformation has been monitored using geodetic and seismic means. Using this rich observational data set and a formal protocol for numerical modeling, the investigators are studying Okmok volcano to address the following questions: (1) What is the distribution of material properties within Okmok? (2) How does anelastic rheology modify the temporal evolution of the deformation field? (3) How do material properties at depth influence the deformation observed at the surface? (4) What are the uncertainties of the model parameters that describe the magma chamber?The impulse-response rheological experiment will improve understanding of the volcano deformation cycle. Specifically, the research project will test four hypotheses: (I) Deformation following the 1997 eruption did not reach a steady state before the eruption in 2008. (II) Viscoelastic stress relaxation contributes to the transient deformation observed during the co-and post-eruptive time intervals. (III) The effective viscosity is several orders of magnitude smaller in the rind of the magma chamber than in the surrounding crust. (IV) The lava flow extruded from Cone A during the 1997 eruption produces a stress field that favors dike propagation from the magma chamber to Cone D.The results will be published in the international, peer-reviewed literature. A graduate student from a group under-represented in Science, Technology, Engineering and Mathematics (STEM) will be trained for a career in geophysical research at the intersection of three disciplines: seismology, geodesy and volcanology. The modeling protocol and approach will be disseminated among the scientific community at an operational level. Investigator Masterlark, a junior faculty member from an institution funded by the Office of Experimental Program to Stimulate Competitive Research (EPSCoR), will offer a short course on how to apply the Finite Element Method to volcanic deformation. Applicants from underrepresented groups will be especially encouraged to participate. The project will enhance collaboration between the investigators and scientists at the U.S. Geological Survey