High-Resolution Seismic Imaging: A Comprehensive Application of Waveform Cross-Correlation to Volcanic Fields

该研究为今后研究与火山活动有关的地热和热液特征以及监测火山活动提供了可能。现场Vp/Vs方法将为泊松？年代比率。与其他技术相比，其结果的精度更高，操作简单，将使Vp/Vs比值成为地震学中更有力的工具，有助于跟踪火山内岩浆和挥发物的运动，并有助于估计活动断裂带中压裂和流体含量的空间变化。火山是一种自然灾害，它会产生多种破坏性现象，如熔岩流、碎片雪崩、有毒气体排放和空气中的火山灰云。随着火山附近地区的发展，越来越多的人和财产受到火山活动的威胁。为了提高我们对火山喷发过程和火山-地震相互作用的认识，以减少生命和财产损失，我们需要提高数据质量和更稳健的估计方法来研究火山系统。在此，我们建议将波形互相关综合应用于多个火山场，以评估精细尺度近源火山结构的时空变化。将应用于建议项目的主要五项研究是：(1)波形互相关，以获得纵波和横波差分时间；(2)复合事件法，以减少地震层析反演中的随机选择误差，并最大限度地增加每个事件的观测次数；(3)三维和四维地震层析成像，使用初到绝对时间和差分时间；(4)相似事件聚类分析和互相关重新定位；S比利用波形数据。拟议的工作将应用于几个火山领域，包括长谷火山口，科索地热区和黄石公园。精细层析速度结构可用于整个火山系统的成像和管道和岩浆室的解析。高分辨率的泊松?S比将有助于跟踪岩浆运动和研究未来喷发危险的可能性，高精度地震重新定位也是绘制岩浆迁移地图的必要条件。这些研究对未来火山系统地震数据的实时分析，以及对火山和破火山口的历史和现状的调查都很有用。

The proposed research will provide a potential to study the geothermal and hydrothermal features related to volcanic activities and to monitor volcanic activity in the future. The in situ Vp/Vs method will provide a new and robust complement to the existing seismic techniques for mapping Poisson?s ratio. The higher precision of results and the simplicity compared with other techniques will make Vp/Vs ratio a more powerful tool in seismology and will help to track movement of magma and volatiles within a volcano and to estimate spatial variations in fracturing and fluid content in active fault zones.Volcanoes are a natural hazard that produces many kinds of destructive phenomena, such as lava flows, debris avalanches, noxious gas emissions, and airborne ash clouds. With the development of areas near volcanoes, more people and property are at risk of volcanic activity. In order to improve our understanding of eruption process and volcano-earthquake interactions to reduce life and property loss, we need improved data quality and more robust estimation methods to study volcanic systems. Here we propose to pursue a comprehensive application of waveform cross-correlation to several volcanic fields to assess fine-scale near-source spatial and temporal volcanic structural variations. The main five studies that will be applied to the proposed project are: (1) waveform cross-correlation to obtain both compressional and shear wave differential times, (2) composite event method to reduce the random picking error and maximize possible number of observations for each event in seismic tomographic inversions, (3) three- and four-dimensional seismic tomography using first-arrival absolute and differential times, (4) similar event cluster analysis and cross-correlation relocation, and (5) estimate of high-resolution in situ Poisson?s ratio using waveform data.The proposed work will be applied to several volcanic fields, including the Long Valley Caldera, the Coso Geothermal Area, and the Yellowstone. Fine-scale tomographic velocity structure can be used to image the entire volcanic systems and to resolve conduits and magma chambers. High-resolution Poisson?s ratios will be helpful to track magma moving and investigate the possibility of future eruption hazards and high-precision earthquake relocations are also essential for mapping magma migration. These studies are all useful for future real-time analysis of seismic data in volcanic systems and for investigating the history and current states of volcanoes and calderas.