Probing the 4D evolution of active magmatic systems through magnetotelluric monitoring

• Applicants: Privatdozent Dr. Corrado Cimarelli; Professor Dr. Max Moorkamp
• Subject Area: Geophysics
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 470447964

Volcanoes pose a significant natural hazard and thus improvements in volcano monitoring techniques have potentially significant impact on preventing loss of life and economic damage. Current volcano monitoring based on seismic and geodetic methods can detect the active movement of magma within the volcanic edifice, but lack sensitivity to petrologic and thermal changes. These two properties, however, have significant influence on the style of eruption and therefore provide essential information to assess the consequences of an impending event. Previous studies have shown how the properties of magma within a volcano can be determined using magnetotellurics (MT), in this proposal we will extend the use of MT to determine temporal variations and provide continuous monitoring. Mount St Helens, perhaps the most studied volcanic system globally, is an ideal laboratory to develop MT as a tool for volcano monitoring applications. We will re-establish the MT measurement locations that were originally occupied during the 2004-08 dome building eruption to identify changes within the magmatic system between an eruptive phase and the current period of quiescence. A set of statistically robust tools to quantitatively identify and assess observational changes in temporal measurements will be developed and adapted for automated use with continuous MT data. The temporal data set will be used to develop a dynamic inverse modelling algorithm optimised to solve for the changes between the two sets of observations, rather than a simple comparison of static inverse results from the two different observational periods. Further, we will install long duration (~24 month) monitoring stations at both Mount St Helens and a second system in an active unrest state at the time of project onset where our Co-I have established research programs (e.g. Sakurajima or Kusatsu-Shirane Japan, and Mammoth Mountain-Long Valley or Kilauea USA). Monitoring stations will be analysed using the developed tools to identify changes in observational data that can be correlated with eruptive behaviour, a first step towards deployment of MT as a monitoring tool. Project outputs include the development of observational tools for temporal MT measurements and a 4D dynamic inversion that considers measurements from multiple observation times and solves for the difference. Furthermore, we will gain valuable insight into the dynamics of the volcanic system at Mount St Helens since the last eruption. The work contributes to both hazard mitigation and advancing our understanding of magmatic and geothermal processes. The introduction of an additional data set sensitive to different physical properties than typically used in monitoring efforts will benefit those tasked with monitoring volcanic systems. At the same time, clarifying the internal dynamics of a magma reservoir is a fundamental outstanding question in the study of volcanic and magmatic systems, which our temporal approach is a step towards resolving.

• DFG Programme: Research Grants
• International Connection: Czech Republic
• Partner Organisation: Czech Science Foundation
• Cooperation Partner: Dr. Graham Hill