An Integrated Analysis of Seismicity, Infrasound, and High-Resolution SO2 Measurements to Determine the Source of Low-Frequency Seismicity at Villarrica Volcano, Chile

对地震活动、次声和高分辨率 SO2 测量进行综合分析，以确定智利比亚里卡火山低频地震活动的来源

• 批准号: 0948526
• 负责人: Gregory Waite
• 金额: $ 22.22万
• 依托单位: Michigan Technological University
• 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: 2010-02-01 至 2014-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0948526&HistoricalAwards=false
• 关键词: Integrated; Analysis; Seismicity; Infrasound; Resolution

Volcanoes produce a rich variety of seismic signals that are unlike those generated during typical earthquakes. While great improvements in the ability to forecast volcanic eruptions have come from recognizing precursory seismic signals, knowledge of the specific mechanisms responsible for the volcanic signals is only generally understood. For example, low-frequency seismic tremor is linked to fluid movement, but many models can explain seismic tremor at any one volcano. By integrating high-resolution seismic, acoustic, and gas emission data, this study will determine the relationship between gas flux and the characteristics of seismic tremor at Villarrica volcano. Villarrica has had persistent gas emission and an active lava lake with continuous, mild, explosive activity since 1984. Because of the continuous low-level activity, direct measurements of emissions of gas, seismicity, and low-frequency sound (infrasound) can safely be made from the summit crater. This study will use simultaneous measurements of seismicity, infrasound and gas emissions. The researchers will deploy arrays of broadband stations to locate and track the depth of low-frequency and volcano-tectonic seismicity, along with distributed infrasonic microphones to characterize the explosive outgassing activity. During 2-3 week field campaigns, they will also collect high-time resolution SO2 emission data, and thermal and visual video of the outgassing activity. All these data will be interpreted jointly to characterize and quantify different styles of outgassing. A 15-month deployment of seismometers and microphones will assure that a significant portion of the outgassing styles is well sampled. The classification scheme for outgassing style they develop during the shorter field campaigns will allow them to calculate a proxy data set for gas emission during the full duration of the deployment so that they may address questions about long-term cycles of activity and the relationship between both deeper local volcanic earthquakes and distant earthquakes on the volcanic system.The transformative potential of this project lies in the integration of these data. The seismic analysis will be based on the strong foundation of established techniques. Infrasound analysis is now seen as critical for monitoring open-vent systems, yet some aspects of infrasound data are not well understood. A novel UV camera, recently developed with support from the National Science Foundation, can image SO2 emission at a rate comparable to eruptive processes. By establishing empirical links between the data, this study will test theoretical models for the generation of seismicity and sound from gas emission and generate important new knowledge on eruptive processes.

火山产生了丰富多样的地震信号，不同于那些在典型的地震中产生的信号。虽然通过识别地震信号，预测火山爆发的能力有了很大的提高，但对火山信号的具体机制的了解只是一般性的。例如，低频地震震颤与流体运动有关，但许多模型可以解释任何一座火山的地震震颤。通过整合高分辨率地震、声波和气体排放数据，本研究将确定气体通量与比利亚里卡火山地震震颤特征之间的关系。自1984年以来，比利亚里卡一直有持续的天然气排放和一个活跃的熔岩湖，持续，温和，爆炸性的活动。由于持续的低水平活动，可以安全地从山顶陨石坑直接测量气体排放，地震活动和低频声音（次声）。 这项研究将同时测量地震活动、次声和气体排放。研究人员将部署宽带站阵列来定位和跟踪低频和火山构造地震活动的深度，沿着分布着次声麦克风来表征爆炸放气活动。在2-3周的现场活动中，他们还将收集高时间分辨率的SO2排放数据，以及释气活动的热和视觉视频。所有这些数据将共同解释，以表征和量化不同风格的放气。为期15个月的地震仪和麦克风部署将确保大部分释气风格得到良好采样。他们在较短的现场活动期间开发的放气方式分类方案将使他们能够计算部署整个期间气体排放的代理数据集，以便他们可以解决有关长期长期活动周期以及火山系统上更深的本地火山地震和远震之间的关系。该项目的变革潜力在于将这些数据抗震分析将以现有技术的坚实基础为基础。次声分析现在被视为监测开放式喷口系统的关键，但次声数据的某些方面还没有得到很好的理解。最近在美国国家科学基金会的支持下开发的一种新型紫外线相机可以以与喷发过程相当的速度拍摄二氧化硫排放。通过建立数据之间的经验联系，这项研究将测试从气体排放产生地震活动和声音的理论模型，并产生关于喷发过程的重要新知识。