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

合作研究：火山变形循环的大地测量和力学模型

• 批准号: 0943965
• 负责人: Kurt Feigl
• 金额: $ 19.07万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0943965&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Geodetic; measurements; mechanical

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

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，2008年又一次。它的活动已使用现代方法进行监测，形成了丰富的观测数据集。调查人员正在开发一个地球物理模型，该模型应该可以解释大多数观测到的活动的时间和位置。这项研究的新信息将直接关系到了解奥克莫克和其他类似火山所造成的时间依赖性火山危险，这些火山位于频繁使用的北太平洋空中交通走廊之下。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或冰岛的赫克拉。奥克莫克是进行这种实验的一个极好的天然实验室，因为利用大地测量和地震手段监测了一个完整的变形周期。利用这一丰富的观测数据集和数值模拟的正式协议，研究人员正在研究奥克莫克火山，以解决以下问题：（1）奥克莫克火山内部物质性质的分布是什么？(2)滞弹性流变学如何修正形变场的时间演化？(3)深度处的材料特性如何影响在表面观察到的变形？(4)描述岩浆房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理解。具体而言，该研究项目将测试四个假设：（一）1997年爆发后的变形在2008年爆发前没有达到稳定状态。(II)粘弹性应力松弛有助于在共同和喷发后的时间间隔观察到的瞬态变形。 (III)岩浆房外壳的有效粘度比周围地壳小几个数量级。(IV)在1997年喷发期间，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。来自科学，技术，工程和数学（STEM）代表不足的一组研究生将接受培训，从事地震学，大地测量学和火山学三个学科交叉的地球物理研究。建模协议和方法将在操作层面上向科学界传播。研究员Masterlark是由实验计划办公室资助的机构的初级教员，以刺激竞争研究（EPSCoR），将提供关于如何将有限元法应用于火山变形的短期课程。将特别鼓励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