Application breakthrough Quantum gravimeter used for the first time for volcano monitoring
Previous collaborative research [1] between the French high-tech company iXblue, which acquired the quantum gravimeter startup Muquans, and the Etneo Observatory of the Seismic Network Center of the Italian National Institute of Geology and Volcanology (INGV-OE) has enabled the world's first use of quantum gravimeters for the detection of gravity changes caused by volcanic activity: even in conditions where other techniques are not available. This device can provide high-quality data even under conditions where other techniques are not available.
01World's first: time series acquisition in an active volcanic crater using atomic interferometric gravimetry
Monitoring subsurface mass (both natural, and engineering) has become increasingly important in recent years. Field gravity measurements are a relatively new application area of quantum technology and are improving in terms of power consumption as well as the size and transportability of the instruments.
The redistribution of mass that occurs below the earth's surface, for example when magma is displaced through the recharge system (feeding system) of an active volcano, may cause small changes in gravity over time. Measuring such changes requires high-precision equipment (e.g., gravimeters). However, standard gravimeters are not suitable for use in harsh field conditions, especially when continuous measurements are the goal. Recent advances in quantum technology have made possible the development of portable gravimeters that can operate successfully under field conditions. As a result, scientists have demonstrated the world's first application of such a quantum gravimeter for monitoring and studying active volcanoes.
Photo of AQG being installed into the crater.
Deployment of the AQG in the crater area at the summit of Mount Etna. (a) schematic of Mount Etna showing the location of the observatory PDN, SLN and MNT; (b) picture of the AQG with the sensor head at a height of 100 cm; (c) panoramic view from the slope to the observatory; (d) section through the observatory and showing the configuration of the AQG installation (not to scale).
Mount Etna is one of the most active and well-monitored volcanoes in the world and has been the site of microgravity measurements using different types of instruments. The equipment is deployed just 2.5 km from the active crater at the summit of Mt. Etna (Mt. Etna, Italy) and provides a high quality gravity time series. Measurements of this time series reflect the gravitational variability of a large number of volcanic processes, including magma and exsolved gas in the upper part of the Mt. Etna plumbing system.
The study focuses on several key breakthroughs.
Demonstration of the world's first time series obtained with an absolute quantum gravimeter in the summit crater region of an active volcano.
The high quality of data produced by the quantum gravimeter to track volcano-related changes, despite unfavorable environmental conditions.
Comparisons with other gravimeter data highlight changes caused by volumetric mass redistribution within the Etna volcano recharge system.
02High-quality data collected despite treacherous volcanic environment
Within the framework of the NEWTON-g project, funded by the EU H2020 program, the Absolute Quantum Gravimeter (AQG), manufactured by iXblue, was improved to make it suitable for use in harsh environmental conditions; and was installed in the summit activity zone of Mount Etna in August 2020 to test its potential as a volcano monitoring instrument. Since then, the AQG has performed near-continuous gravity measurements: iXblue and INGV-OE have provided a four-month time series of gravity data.
Gravity time series and wavelet coherence analysis. (a) gravity time series from PDN (August 1-December 3, 2020); (b) gravity time series from SLN; (c) wavelet coherence between the signals in panels (a and b).
The derivation of gravity time series and mass source depths for the high coherence phase.
The gravimeter was installed approximately 2.5 km from the active crater of Mount Etna. Consistent high quality data were generated despite extremely unfavorable environmental conditions (lack of power, drastic temperature changes, presence of dust and corrosive volcanic gases) and high volcanic tremor during the measurement period.
"The AQG installed in the crater area at the summit of Mount Etna provided a gravity time series without the instrumentation problems that affect other gravimeters. Even under unfavorable environmental conditions, it has the potential to detect small gravity variations on different time scales, reflecting the subsurface mass changes associated with the volcano." Daniele Carbone, INGV-OE senior researcher and co-author of the paper, said.
Changes in the Earth's gravitational field can reveal useful information about the subsurface: from the presence of tunnels and caves to the dynamics of groundwater and even magma. iXblue's AQG is a turnkey, portable and easy-to-use quantum sensor that uses "atomic interferometry" quantum technology to measure changes in the gravitational field. Using a laser-cooled cloud of rubidium atoms near absolute zero as the test mass, iXblue's AQG can sense small changes in gravity.
03Atomic Interferometry: Growing Maturity and Wide Applications
The successful demonstration of an atomic interferometry-based quantum sensor in this experiment not only opens new horizons for gravity measurements on volcanoes, but also for the application of gravity methods to environments that may require reliable in situ measurements in harsh environments, such as groundwater dynamics studies, geothermal energy systems, and carbon sequestration.
Vincent Menoret
Vincent Menoret, R&D Manager of iXblue's Quantum Sensors Division, explains, "Our AQG can detect small changes in the Earth's gravity. iXblue's latest advances in quantum sensor development with its partners have allowed us to develop portable gravimeters that can operate and operate in field conditions, and quantum technology industrialization is about to become a reality."
"These results confirm the operational possibilities of quantum gravimetry and open new horizons for the application of gravimetry in geophysics. This outstanding achievement is also a clear manifestation of the maturity of cold atom technology, which will have wider implications in the field of quantum computing with neutral atoms, and long-range quantum communication with quantum repeaters." Jean Lautier-Gaud from iXblue's Quantum Sensors Division and co-author of this paper concludes.
Reference link：
https://www.ixblue.com/ixblue-and-the-national-institute-of-geophysics-and-volcanology-present-the-first-application-of-quantum-technology-to-volcano-monitoring-on-mount-etna/
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL097814
