Monitoring the La Soufrière de Guadeloupe hydrothermal system with a regularly-spaced muon telescope network

Long-term muon tomography allows to track density changes in a volcano by continuously measuring the flux of cosmic muons traversing the geological body. In the context of volcanic hydrothermal systems, this approach can help to determine zones of preferred steam formation, condensation, water infiltration and storage. A single muon telescope provides an integrated 2-D average-density section of a volcanic system, leading to an intrinsically ambiguous inverse problem. To overcome this limitation, we present the first results of imaging the La Soufriere de Guadeloupe dome and shallow hydrothermal system with several simultaneous muon telescopes viewing the dome from different positions around its base. Our strategy provides better constraints on the spatial location of the density changes and an improved estimate of the amount of mass involved in these changes. Therefore, we can better characterize water phase changes and estimate pore pressures. We compare the temporal density variations extracted from different muon telescopes to time-series of rainfall on the summit recharge area and temperature profiles in the vicinity of ground thermal anomalies and summit fumaroles.