Minute-scale dynamics of recurrent dike intrusions in Iceland with fiber-optic geodesy

Creators: Li, Jiaxuan^{1, 2}; Biondi, Ettore¹; Heimisson, Elías Rafn³; Puel, Simone^{1, 4}; Zhai, Qiushi¹; Zhang, Shane¹; Hjörleifsdóttir, Vala⁵; Wei, Xiaozhuo¹; Bird, Elijah¹; Klesh, Andy⁶; Kamalov, Valey⁷; Gunnarsson, Theodór⁸; Geirsson, Halldór³; Zhan, Zhongwen¹

1. California Institute of Technology
2. University of Houston
3. University of Iceland
4. Moody's, Newark, NJ, USA.
5. Reykjavík University
6. Jet Propulsion Lab
7. Valey Kamalov LLC, Gainesville, FL, USA.
8. Google (United States)

Abstract

Continuous geodetic measurements near volcanic systems can image magma transport dynamics, yet resolving dike intrusions with high spatiotemporal resolution remains challenging. We introduce fiber-optic geodesy, leveraging low-frequency distributed acoustic sensing (LFDAS) recordings along a telecommunication fiber-optic cable, to track dike intrusions near Grindavík, Iceland, on a minute timescale. LFDAS reveals distinct strain responses from nine intrusive events, six resulting in fissure eruptions. Geodetic inversion of LFDAS strain reveals detailed magmatic intrusions, with inferred dike volume rate peaking systematically 15 to 22 min before the onset of each eruption. Our results demonstrate DAS's potential for a dense strainmeter array, enabling high-resolution, nearly real-time imaging of subsurface quasi-static deformations. In active volcanic regions, LFDAS recordings can offer critical insights into magmatic evolution, eruption forecasting, and hazard assessment.

Copyright and License

Funding

This work was supported by the Gordon and Betty Moore Foundation, the US National Science Foundation (NSF) (EAR-1848166), and the NSF Center for Geomechanics and Mitigation of Geohazards (1822214).

Acknowledgement

We thank Ljósleidarinn for providing the fiber access. We thank M. M. Parks for valuable discussions on dike geometry and K. Jónsdóttir, S. Barsotti, E. B. Gestsson, and P. Erlendsson for coordinating the LFDAS volcanic eruption early warning efforts. J. L. thanks W. Zhu for discussions on LFDAS with telecommunication fiber cables in early 2023. The fiber-optic geodesy method is part of a provisional U.S. patent filed by the California Institute of Technology (CIT file no. CIT-9251-P)

Data Availability

The downsampled LFDAS data before and after denoising for all nine intrusive events in this study is available at CaltechDATA: https://doi.org/10.22002/tw5s6-nd034.

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