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

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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.