Preliminary Statement SAC 27
November 4th, 2022
The Montserrat Volcano Observatory reports that Soufrière Hills Volcano has produced higher rates of degassing and volcano-tectonic earthquakes since around 2019, and these have been sustained over the last 12 months. The longer-term trend of inflation of the island has continued at the same rate as in previous years.
Measured SO2 fluxes have averaged ~400 tonnes per day over the last 12 months. An average of 9 volcano-tectonic earthquakes per week have been observed. Thermal camera images of fumaroles on the dome indicate that the temperature of fumaroles is similar to previous years, with maximum temperatures of 545 °C. Monitoring of ground deformation indicates a slow but continuous lengthening over the island, and a maximum uplift of about one centimetre over the last year. This deformation trend is consistent with that observed over the previous 12 years.
Taking these observations together, we conclude that the volcano remains in a state of unrest. The best explanation for this unrest is continued supply of magma and gas from depth to a magmatic reservoir. Thus, a resumption of lava extrusion, or explosions, remain a possibility in the future. However, we consider that the most likely scenario for the next year is a continuation of the current state.
The volcano, with its large lava dome, is still a potential source of hazards within Zone V, including explosions, pyroclastic flows and lahars. The chance that explosions or pyroclastic flows will occur within the next year remains low. Continuous monitoring of the volcano remains essential.
