The monitoring of volcanic and ionospheric activity is conducted with the use of accurate reference stations

The islands of Saba and St Eustatius (Statia) are volcanic islands in the Caribbean region of the Netherlands, where active volcanoes exist due to plate movements. In order to monitor the activity of these volcanoes, KNMI (Royal Netherlands Meteorological Institute) has installed PolaRx5S and PolaRx5 GNSS receivers, seismometers and temperature sensors. These were used to monitor the activity of Mount Scenic on Saba and Quell Volcano on St Eustatius.

The PolaRx5S receiver has an ionospheric monitoring function that allows the collection of measurements for space weather studies. Together with the PolaRx5S receivers of INGV (Italian National Institute of Geophysics and Volcanology), located on the islands of Saba and Statia, these receivers form an extensive space weather monitoring network for ionospheric scintillation.

Global Navigation Satellite System (GNSS) observations are very useful for monitoring active volcanoes, and KNMI has installed two monitoring sites with PolaRx5S reference receivers and PolaNt Choke Ring B3/E6 antennas, as well as six sites with PolaRx5 reference receivers over the past five years. These sites use signals from multiple GNSS constellations to calculate the position of each antenna with a high enough accuracy to detect subtle movements caused by minor deformations of the volcano's bedrock and surface.

Detailed information on the PolaRx5S receiver can be found on the website of its manufacturer, Septentrio, a company specialising in providing high-precision GNSS solutions for a wide range of high-precision positioning and navigation applications.The device is renowned for its low power consumption, high data logging and transmission speeds as well as advanced anti-jamming technology. The PolaRx5 series receivers are Septentrio's flagship products, they combine the latest GNSS technology with patented anti-jamming features to ensure reliable data in the most demanding environments.

Through these advanced monitoring equipment and techniques, KNMI is able to actively monitor volcanic and seismic activity and contribute to tsunami warning in the Dutch Caribbean. The application of those technologies not only improved the prediction of natural disasters, but also demonstrated the important role of GNSS in scientific research and disaster prevention.