Saba Volcanic/seismic monitoring continues during pandemic

The Bottom, Saba – The Royal Netherlands Meteorological Institute KNMI continues its volcanic/seismic monitoring work on Saba despite the challenges of the COVID-19 pandemic with associated travel restrictions and delayed delivery of new equipment.

KNMI experts will return to the island in April to collect data, inspect, and repair, monitor equipment where necessary, and to install a new Global Navigation Satellite System (GNSS)/seismic monitoring station on the North Coast. In its most recent update, KNMI volcanologist Elske De Zeeuw-van Dalfsen and seismologist Reinoud Sleeman explained that seismometers “SABY” at the airport, “SABW” in Windwardside, and “SABA” at St. John’s are functioning well and produce data of good quality to detect earthquakes. The fourth seismometer, “SABQ” in The Bottom, is currently not functioning due to technical issues and is awaiting repair by the manufacturer.

The two GNSS stations in St. John’s and at the airport worked well most of 2020. For each instrument, the KNMI calculates the daily position very precisely. The GNSS station in St. John’s has been operational since January 2018 and the one at the airport since February 2019. In January 2020, the KNMI installed a GPS (Global Positioning System) receiver in The Bottom. This instrument measures its precise location on the ground, allowing it to track its movement.

The new GNSS/seismic station at Grey Hill, along the North Coast, is planned for April 2021. The equipment and construction materials will be shipped to Saba in February. This installation, unlike the other GNSS/seismic equipment, will be completely stand-alone. Satellite communication will be used to send data to the KNMI, and solar panels/batteries will be used to power this site in this uninhabited area.

In January 2020, during the last visit of the KNMI experts, the continuous temperature data from the underwater hot spring opposite Green Island were collected. Measurements at the hot spring are taken every 20 minutes and stored locally. The maximum temperature remains constant at 82 degrees Celsius. The experts will collect the 2020 temperature data at the hot spring during the next visit in April.

In March 2020, a member of the public reported multiple cracks in the Green Gut area along the road between English Quarter and Hell’s Gate. The crack along the wall was 60 cm deep and had warm moist air venting from it at about 50 °C. The Green Gut is an unstable area, but the warm air is unusual. It may be that compaction and rotting of waste cause heath to form. There is always the possibility that the volcano forms a vent or already had it there in the past. If this would be the case, the temperatures are still relatively low, and there is no other evidence of volcanic origin like sulfur or other mineral deposits. The KNMI experts will bring a thermal camera to closely inspect the area during the next visit.

Rangers of the Saba Conservation Foundation (SCF) in March 2020 reported dead mountain mahogany trees in a 10x10m2 area close to the top of Mt. Scenery. A SCF team under the guidance of the KNMI investigated the area for other signs of volcanic activity such as volcanic deposits (ash, sulfur), fumes, and heat release. No such evidence was found, suggesting volcanic activity did not cause the trees to die. The SCF captured photos and videos for future reference. A new photo and video survey in January 2021 clearly showed the regrowth of vegetation, confirming that there is no volcanic activity in the area.

In the update, the KNMI also addressed the increased activity levels of several volcanoes in the Caribbean. It was explained that the Caribbean volcanoes were all formed by the same process, namely the subduction at the plate boundary. However, the volcanoes do not share the same magma chamber, nor are they connected by long magma conduits. Therefore, a volcanic eruption on one island can not trigger an eruption on another island, the KNMI assured.

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