Fiber-Optic Observation of Volcanic Tremor through Floating Ice Sheet Resonance
Abstract
Entirely covered by the Vatnajökull ice cap, Grímsvötn is among Iceland’s largest and most hazardous volcanoes. Here we demonstrate that fiber-optic sensing technology deployed on a natural floating ice resonator can detect volcanic tremor at the level of few nanostrain/s, thereby enabling a new mode of subglacial volcano monitoring under harsh conditions. A 12.5 km long fiber-optic cable deployed on Grímsvötn in May 2021 revealed a high level of local earthquake activity, superimposed onto nearly monochromatic oscillations of the caldera. High data quality combined with dense spatial sampling identify these oscillations as flexural gravity wave resonance of the ice sheet that floats atop a subglacial lake. Although being affected by the ambient wavefield, the time–frequency characteristics of observed caldera resonance require the presence of an additional persistent driving force with temporal variations over several days, that is most plausibly explained in terms of low-frequency volcanic tremor. In addition to demonstrating the logistical feasibility of installing a large, high-quality fiber-optic sensing network in a sub arctic environment, our experiment shows that ice sheet resonance may act as a natural amplifier of otherwise undetectable (volcanic) signals. This suggests that similar resonators might be used in a targeted fashion to improve monitoring of ice-covered volcanic systems. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000567658Publication status
publishedExternal links
Journal / series
The Seismic RecordVolume
Pages / Article No.
Publisher
Seismological Society of AmericaOrganisational unit
03971 - Fichtner, Andreas / Fichtner, Andreas
03971 - Fichtner, Andreas / Fichtner, Andreas
Funding
821115 - Real-time Earthquake Risk Reduction for Europe (EC)
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