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SeisMic Observations of deep VolcAnic pRocesses

Subject Area Geophysics
Term from 2020 to 2025
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 443363136
 
Final Report Year 2024

Final Report Abstract

The SaMOVAR project aimed to investigate deep volcanic processes through seismic observations, using the Klyuchevskoy Volcanic Group (KVG) in Kamchatka as a natural laboratory. This region, the largest and most active subduction zone volcanic cluster globally, provided a unique opportunity to study magma transfer mechanisms, crustal and mantle anisotropy, and pre-eruptive changes in volcanic systems. The project focused on understanding the physical processes controlling magma and fluid pressure transport from deep sources to shallow reservoirs. To achieve these goals, data from the temporary KISS network, which included 80 broadband seismographs operating in 2015–2016, and long-term records from the permanent Kamchatka seismic network were analyzed using techniques such as shear-wave splitting, receiver-function analysis, tomographic imaging, and ambient noise-based monitoring. Despite challenges posed by the Russia-Ukraine war, which limited access to certain datasets, the project achieved significant advancements by leveraging alternative regional and international datasets. Key findings revealed complex anisotropy patterns in the mantle beneath the Kuril-Kamchatka subduction zone, with toroidal flow at slab edges influencing mantle dynamics. Local shear-wave splitting indicated weak anisotropy in the mantle wedge, while teleseismic splitting suggested strong anisotropy in the subslab mantle, consistent with trench-parallel flow. Temporal seismic velocity changes linked to volcanic and tectonic processes were identified, including evidence of shallow magmatic reservoir inflation at Bezymianny Volcano prior to an eruption. The episodically changing noise field character is a particular challenge in volcanic environments and was addressed using a temporal clustering that identified periods of relatively stability which could be used for monitoring. Another common challenge for long term interferometry based velocity monitoring arises from changes in the station configuration. This problem has been addressed at Mount St. Helens which has been instrumented since decades but with fluctuating stations. A strategy based on the spatial imaging of velocity changes was developed to integrate data from new stations into a coherent 4D picture of changing seismic velocities. The project developed innovative tools, such as the open-source ”SeisMIC” software, enabling efficient seismic velocity monitoring.

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