Saba is one of the islands that form the volcanic arc of the Lesser Antilles. Because of its potential for volcanic activity, it requires regular monitoring for signs of increased activity. Over the years, the KNMI (Koninklijk Nederlands Meteorologisch Instituut) has been building and continues to build a permanent and real-time monitoring network for both volcanic and seismic activity.
The current monitoring network installed on the island consists of four seismometer sites in each of the villages. Two of these sites are co-located with GNSS (Global Navigation Satellite System) sensors; these sites are in St. Johns and Flat Point. Additionally, there is a thermometer that monitors the temperature of the hot springs on the coast opposite Green Island.
To further strengthen the current monitoring network, a third co-located GNSS and a seismometer site are required in an area where there was an instrumentation gap. This location is Grey Hill along the North Coast Trail. The GNSS sensor accurately measures the movement of the sensor in three dimensions, which would indicate if the ground is expanding, thus signaling a change in volume of the volcano and regional plate tectonics.
The instruments’ installation is challenging since all materials need to be transported over the North Coast Trail. To minimize any risk, the Dutch military will be asked to help carry KNMI materials to Grey Hill on foot.
The installation of the new instruments is planned for April 2021. To be able to plan this logistically challenging operation, three marines will scout the route this week. The marines are essential workers and will adhere to the COVID-19 measures in place.