Skip to content

Resistivity: a new volcano monitoring tool?

Lore Vanhooren1,2 , Thomas Hermans1, Corentin Caudron2

Abstract

Geo-electric methods have become increasingly important in the characterization of volcanic systems. Due to their sensitivity to temperature, saturation, and certain clays and minerals, they have applications in reservoir characterization and edifice stability but studies remain static. With the ERupT project, we assess the suitability of ERT and IP to visualize the dynamics in volcanic hydrothermal systems, aiming long-term to improve hazard assessment relating to hydrothermal eruptions. A monitoring profile was installed on the Reykjanes Geothermal field (Iceland) where ERT and IP are measured daily since 23/10/2022 (still ongoing with a few interruptions). The 2021 eruption at Fagradalsfjall marked a new age of volcanism in the Reykjanes peninsula. Since the start of our campaign, Fagradalsfjall erupted on July 10th, 2023, after that the Svartsengi system activated and has been periodically erupting since December 18th, 2023. The eruption sites are located at respectively 10 and 25 km from the fieldsite. Although the ERT system is located at a considerable distance from both eruption sites and the investigation depth is shallow (down to ~50m), we observed signals possibly related to both eruptions and the accompanying unrest, on top of more local signals (e.g., meteorological). Prior to the 2023 eruptions of Fagradalsfjall and Svartsengi, our system recorded an increase in resistance (<100%) followed by an earthquake swarm and later the eruptions. We hypothesize that the ERT signal is related to magma degassing during uprise. This is the first study using ERT as a volcano monitoring tool, showing great potential for future monitoring.