Where does a volcano break? Using self-potential reiteration to forecast the precise location of major destructive events on active volcanoes: the case study of the Piton de la Fournaise 2007 caldera collapse

Marie Chaput,Anthony Finizola,Aline Peltier,Stéphanie Barde-Cabusson,Nicolas Villeneuve,Marie Crovisier

doi:10.30909/vol.02.02.151159

Abstract

The Dolomieu caldera collapse (April 2007) was one of the most outstanding events of recent decades at Piton de la Fournaisevolcano. Forecasting such a destructive event is difficult but since then, the development of tools and monitoring networks has improved our knowledge of the dynamics of volcano instability. However, the precise location of volcano failure remains hard to constrain. Here, we show that reiteration of self-potential (SP) measurements along a profile prior to caldera collapse brings valuable insights on the most instable areas around the Dolomieu crater, revealing information not visible on one single SP acquisition. In particular, the SP dynamic highlights the presence of low cohesion/low strength materials at depth despite a lack of surface expression. Our data show that preferential failure area can be precisely identified at the meter scale, highlighting the relevance of SP reiteration as a tool for locating instabilities in both volcanic and non-volcanic environments.

Highlights

Summit caldera collapses are common features of basaltic to silicic volcanoes that can occur repeatedly throughout their evolution and are commonly associated with large eruptive crises
The location and orientation of this reiteration profile were guided by the highest SP variation identified on the SP map [Barde-Cabusson et al 2012, Figure 1B]
The SP reiteration profile extended between the Soufrière pit crater and the Dolomieu crater rim, crossing this highest SP anomaly

Summary

Introduction

Summit caldera collapses are common features of basaltic to silicic volcanoes that can occur repeatedly throughout their evolution and are commonly associated with large eruptive crises. Several caldera collapses have been reported, including Fernandina volcano (Galápagos Islands) in 1968 [e.g. Caldera formation is usually guided by preexisting structures such as ring fault systems and fractures around the summit. Our results show that SP mapping combined with SP reiteration can provide valuable information about the structural behavior of calderas and may significantly help in assessing associated hazards. We propose the SP method as a tool for the detection of areas of mechanical weakness on volcanoes, more prone to failure during caldera collapse

Background

Self-potential surveys at Piton de la Fournaise

Results

Discussion and Conclusions