Scientists monitoring Montserrat’s Soufrière Hills Volcano say they have noticed subtle changes which indicate that the potential for increased activity remains.
In a statement released on Friday morning, from Director of the Montserrat Volcano Observatory (MVO) Dr. Graham Ryan and Chair of the Scientific Advisory Committee (SAC) Prof. Jurgen Neuberg, the scientists noted that the volcano has “been in a state of unrest since the end of lava extrusion in February 2010.”
While the MVO’s weekly reports indicate that activity at the volcano has been low for the past twelve years, the scientists said the reports do not adequately account for the subtle changes that have been occurring over time.
“Volcano-tectonic earthquake activity has been very low since the end of extrusion, with an average of about one earthquake per day. We have, however, seen a small increasing trend in the daily rate of earthquakes over the last few years, rising from about 0.4 per day in 2018 to around 1.2 per day in late 2021. Between 2013 and 2018, routine monitoring of fumarole temperatures on the lava dome indicated a general cooling trend. Since 2018, however, an increase in the temperatures of some fumaroles on the volcano has been observed. The largest increase at one particular fumarole of about 200 °C brings it back up to approximately 500 °C, similar to temperatures measured in 2013,” the report read.
In a press conference on Friday to discuss the statement and last week’s Scientific Advisory Committee (SAC) Meeting. the MVO director said in 2021 they began to look more carefully at the data they have been collecting over the years. Over the past few months, he added, they have become more and more convinced that it is a real change happening. However, the changes are not significant enough to warrant increasing the current risk level of the volcano from one.
Ryan dispelled concerns about impending eruptions, explaining that eruptions would be preceded by precursors which would signify a ramping up of volcanic activity. These precursors include “significant low-frequency seismicity and swarms of volcano-tectonic and/or hybrid earthquakes.”
Prof Neuberg told the media that looking at a bigger data set was how they were able to recognise the subtle changes. I said the entire island continues to inflate at about a centimeter a year. “The instruments can see the inflation that you cannot from your verandah. It is inflating and we need to clearly take this into account. There is a difference between unrest and eruptive activity.”
Soufriere Hills, he said, releases tonnes and tonnes of Sulphur Dioxide daily. According to the statement “the Sulphur dioxide fluxes between 2020 and 2021 are on average 100 to 200 tonnes per day higher than in the period 2018 to 2019 but remain lower than those observed in the period 2012 to 2013.”
“We should not make the mistake and relax because we don’t see any significant change. This is a reminder that this volcano is still active,” the professor added.
Premier Joseph Farrell said the report is a reminder that the volcano is still active but the changes do not indicate any eruptions are imminent.
Governor Andrew Pearce commended the MVO and the committee for their continued work to monitor the volcano.
The MVO will continue to analyse the data and closely monitor the volcano and will provide updates as further information becomes available.