Topographical Effects on Volcano Deformation Signal Intensity: Implications for GPS Network Configuration

Volcano GPS networks can capture vital information during volcanic unrest to aid with hazard assessment and eruption forecasting, but can be hindered by their discrete point locations and possibly miss key spatial information. We show how numerical models can reveal controls on spatial deformation signal intensity compared against GPS network design. Using the GPS network at Soufri & egrave;re Hills Volcano (SHV), Montserrat, and a range of models, we explore expected surface deformation patterns. Peak horizontal deformation is located offshore, highlighting the difficulties with geodetic monitoring on small ocean-island volcanoes. Onshore areas where the deformation signal is expected to be high are also identified. At SHV, topography plays a greater role in altering the relative distribution of surface displacement patterns than subsurface heterogeneity. Our method, which can be adapted for other volcanoes, highlights spatial areas that can be targeted for effective GPS station placement to help improve deformation monitoring efficiency. Volcanoes present a hazard to lives, livelihood and infrastructure. Monitoring volcanoes allows scientists to track changes happening both inside and around the volcano. The build-up of magma beneath a volcano can cause the ground surface to change shape; this deformation can be measured using GPS technology as part of typical volcano monitoring. GPS recording sensors are placed around the volcano as part of a network but it is difficult to know where best to place them. We can use computer modeling and an understanding of a volcano to predict areas around the volcano that might deform more than others, and which therefore might be good positions to deploy GPS sensors. Using Soufri & egrave;re Hills Volcano (SHV), Montserrat, as our case study, we highlight potential areas with high deformation signal but also show that a lot of deformation in this region occurs on the seafloor. Comparing different models suggests that the shape of the topography of the island strongly influences the pattern of the surface deformation signal. Our approach can be generalized for application to other volcanoes to help decide potential locations for GPS site locations where expected deformation signals are high. This work contributes to improving the efficiency of volcano deformation monitoring. We use numerical models to identify regions of higher and lower expected surface deformation signal intensity Topography is the key control influencing spatial patterns of surface deformation intensity at Soufri & egrave;re Hills Volcano Our approach identifies areas for GPS site placement to improve deformation monitoring efficiency and network configuration