ALBERT

Description: Detection of geophysical signatures associated with a geologic event, such as a volcanic eruption, is key to understanding the underlying physical processes and making an accurate hazard assessment. Magma reservoirs are the main repositories for eruptible magma, and understanding them requires the ability to detect and interpret changes in the magmatic system from surface measurements. Traditionally, monitoring for these changes has been done with seismic and geodetic approaches, both of which require dynamic ‘active’ changes within the magmatic system. Neither of these techniques is sensitive to the petrology or temperature of the magma though. Thus, additional monitoring techniques able to detect ‘static’ phase changes in the evolving magma and the thermal structure of the magma reservoir are needed. The magnetotelluric method, measures subsurface electrical properties and is sensitive to both ‘magma on the move’ and petrological changes that occur within the magma reservoir. Using Mount St Helens where a detailed magnetotelluric survey was completed during the most recent dome building eruptive phase 2005-06, and is now in a period of quiescence, we compare the original measurements to repeated measurements in the same locations in 2022 to develop temporal analysis approaches required for monitoring. In addition to the repeat campaign we have deployed 4 long-term continuous monitoring stations with telemetry to local servers. First, qualitative, comparisons of the data from different time periods indicate some significant changes in subsurface conductivity. We present an overview of the newly acquired data and the monitoring setup and discuss where the most significant changes occur.