Analysis of the Seismicity Associated with the 1986 Eruptionof Mt. St. Augustine, Alaska: Relationship to Shallow Crustal Magmatic Processes

与 1986 年阿拉斯加圣奥古斯丁山喷发相关的地震活动分析：与浅地壳岩浆过程的关系

基本信息

批准号：
8721207
负责人：
Juergen Kienle
金额：
$ 6.65万
依托单位：
University of Alaska Fairbanks Campus
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
1988
资助国家：
美国
起止时间：
1988-02-01 至 1990-01-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=8721207&HistoricalAwards=false
关键词：
Analysis Seismicity Associated 1986 Eruptionof

项目摘要

We propose to use space-time behavior of seismicity to obtain an improved model of Mt. St. Augustine's plumbing sytem and to infer the magma migration processes associated with its 1986 eruption. The ability to accurately determine hypocentral parameters would be achieved by using a) a realistic two- dimensional model of the volcano's seismic velocity structure and b) both travel time and amplitude data of seismic waves recorded at seismic stations on the volcano. Preliminary results using data from an eruption in 1976 indicate that amplitude data from forward modeling based on the Gaussian beam method might provide a powerful means of constraining focal depth. The potential of that method for volcano seismology requires detailed exploration, which we propose to conduct in this investigation. Magma movement up the conduit of a central stratovolcano always produces microearthquake activity due to fracture propagation, dike emplacement, brecciation of host rocks and eventually vent excavation. Precise location (especially of depth) of precursor earthquakes prior to eruptions can give important clues about the evolution of the physical/chemical instability in the magma reservoir that eventually erupts. If we succeed in developing an earthquake location scheme that is highly sensitive to depth of focus it could have an important application for eruption prediction.

我们建议利用地震活动的时空行为来获得圣奥古斯丁山管道系统的改进模型，并推断与其 1986 年喷发相关的岩浆迁移过程。通过使用a）火山地震速度结构的真实二维模型和b）火山地震台记录的地震波的传播时间和振幅数据，可以实现准确确定震源参数的能力。使用 1976 年喷发数据的初步结果表明，基于高斯束方法的正演模型的振幅数据可能提供约束焦深的有力手段。这种火山地震学方法的潜力需要详细的探索，我们建议在本次调查中进行。由于裂缝扩展、岩脉就位、主岩角砾化以及最终的喷口开挖，岩浆沿着中央成层火山的管道向上运动总是会产生微地震活动。喷发前前兆地震的精确定位（尤其是深度）可以为最终喷发的岩浆库中物理/化学不稳定性的演变提供重要线索。如果我们成功开发出对震源深度高度敏感的地震定位方案，它将在喷发预测中具有重要的应用。