Chapter 11 Volcano geodesy at the Soufrière Hills Volcano, Montserrat: a review

Abstract

Geodetic surveying is a core volcano monitoring technique. Measurements of how the crust deforms can give valuable insight into the mechanisms and processes that drive an eruption, and the way in which they change. Various geodetic observables, including ground deformation and gravity changes, have been recorded on Montserrat throughout the eruption. Instrumentation and surveying networks used to make such measurements have evolved significantly since 1995, providing increasingly accurate and robust observations. The detailed research that has been facilitated by these rich geodetic datasets has illuminated many aspects of the Soufrière Hills Volcano (SHV) and demonstrated eruptive mechanisms that are relevant to the study of other volcanoes. We have compiled a history of the geodetic study of the eruption on Montserrat, detailing the development of surveying techniques, network design and data processing since 1995. We then underline some of the key geodetic observations and review some of the most significant research that has contributed to our understanding of this volcanic system. Finally, we apply a series of typical deformation inversion models to deformation observations, and discuss the parameter sensitivity of such modelling approaches and how confidently they can be applied to identify the characteristics of the mechanisms feeding the eruption.

Chapter 1 An overview of the eruption of Soufrière Hills Volcano, Montserrat from 2000 to 2010

“…When lava is extruding (at high rates of c. 5 m 3 s 21 ) the surface deflates, and then inflates in times of non-extrusion (e.g. Odbert et al 2014a). Modelling the crust as an elastic body shows that the source of the deformation is centred below the volcano at mid-crustal depths (with a mean of c. 13 km: Mattioli et al 2010).…”

“…Slowly, from a variety of geodetic measurements supported by insights gained from seismic tomography and petrology, a picture of the geometry and dynamics of the andesite magma transport is being resolved, although that picture is still quite fuzzy at depth (Barclay et al 1998;Mattioli et al 2010;Voight et al 2010b;Paulatto et al 2012;Odbert et al 2014a). The shallower components of the transport system are now thought to be represented by a dyke with a cylindrical conduit above (Costa et al 2007;Chardot et al 2010;Linde et al 2010).…”

Deposit loading and its effect on co-eruptive volcano deformation

“…1). A key observation from cGPS monitoring has been the occurrence of marked deflation/inflation cycles, lasting a few months to a few years, that are strongly correlated with lava extrusion and repose, respectively (Odbert et al, 2014b). These signals have widely been interpreted and modelled as the elastic crustal response to depressurisation-pressurisation cycles of upper crustal (>5 km) magma reservoirs (Elsworth et al, 2008;Mattioli et al, 1998;Odbert et al, 2014a), representing repeating, recharging cycles.…”

The Variability of Refractivity in the Atmospheric Boundary Layer of a Tropical Island Volcano Measured by Ground-Based Interferometric Radar

“…Given the variability of the refractivity revealed here, how useful would the GPRI data be for measuring ground motions due to volcanic activity on Soufrière Hills Volcano (Odbert et al 2014)? The island-wide monitoring of deformation is undertaken by the Montserrat Volcano Observatory using GPS, and GPRI does not help in that regard.…”

“…Our study was conducted from a single site over a period of 24 h, from 1020 local time (LT) on 4 August to 1020 LT on 5 August 2013. Based on the lack of volcanic activity and the known background rates of surface deformation on Montserrat (Odbert et al 2014) we assume that over this short period we can ignore any volcano-related surface motions. Fig.…”