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Session: An Innovative Photonic Vision of Volcanoes and Geothermal Systems

Type: Oral

Date: 10/10/2024

Time: 09:15 AM

Room: Stanley Park Ballroom

Fibre-Optic Seismology on Remote, Subglacial, Submarine and Actively-Erupting Volcanoes

We present highlights of Distributed Acoustic Sensing (DAS) experiments in different volcanic settings. The experiments show several ways in which DAS can contribute to volcano monitoring, and which challenges need to be overcome before DAS can become standard practice as a volcano monitoring tool.

Mount Meager is a volcano in Canada with a high geothermal potential and it is prone to severe landslides. We deployed a 3 km long fibre-optic cable along a ridge, and partly trenched it into the glacier. We record previously unknown high-frequency events that we analyse with beamforming, and low-frequency tremor that may be related to the geothermal activity.

We deployed a 12 km long fibre on Grímsvötn, which is covered by the Vatnajökull ice cap. We discover high levels of previously undetected microseismicity using an image processing algorithm and locate events with local magnitudes as low as -3 using the Hamiltonian Monte Carlo algorithm. These events are used to set up a full-waveform source inversion workflow, with the option to expand to a full-waveform tomography.

We interrogated a 45 km long dark fibre that extends from the island of Santorini, Greece, Northwards, past the submarine volcano Kolumbo. We detect more events than the local network, and we show the challenges of a cable geometry that is not ideal. We analyse the limitations of the cable layout to locate events for observed and synthetic data, with both homogeneous models and full-waveform modelling in a complex environment.

We monitored the seismic unrest at Svartsengi, Iceland, between November 2023 and April 2024 with an 8 km dark fibre near the eruption site. We set up live data streaming and analysis to aid the monitoring by the Icelandic Met Office. We use the detected events to set up a time-dependent non-linear tomography of the intrusion.

This research shows the potential of DAS to detect events with a lower detection threshold, locate events depending on its cable geometry, characterise events and model the subsurface using a full-waveform framework that takes the complex environment into account.

Presenting Author: Sara

Additional Authors