Absolute Quantum Gravimeter as a promising field sensor for volcano monitoring

Soufrière, an active volcano in Guadeloupe (French West Indies) monitored by the Volcanological and Seismological Observatory of Guadeloupe (OVSG), requires a comprehensive understanding of mass transfers, including water movements. To address this, a gravity repetition network was established in the 1980s following the volcano's last major eruption in 1976. In 2011, initial absolute measurements were conducted using a Micro-g Lacoste portable absolute gravity meter A10 #14.

 

As part of the EQUIPEX RESIF program, aimed at meeting the scientific community's seismic and gravimetric instrument needs in France, the first absolute quantum field gravimeter (AQG-B01) was acquired. This advanced instrument, designed for diverse applications, including volcano gravity monitoring, utilizes atom interferometry with lasers to measure gravity by manipulating 'atomic waves' with a cloud of free-falling cold atoms at a cycling rate of 2 Hz.

 

In March 2023, a fieldwork was undertaken with the AQG-B01 as an initial step toward modern gravity monitoring of Soufrière. The specific goals included reoccupying stations within the microgravity network and identifying new sites for expanding the network, selecting an appropriate location for a permanent station near the summit based on a Lacoste&Romberg D meter, testing the AQG-B01 under challenging tropical conditions (humidity up to 85%, mean temperature of 24°C), assessing the use of an external power supply for the AQG, and evaluating the ease of installation and accuracy of measurements with the AQG, as specified by the manufacturer.

This work primarily focuses on the latter three objectives.