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- Title
Stacking of Distributed Dynamic Strain Reveals Link Between Seismic Velocity Changes and the 2020 Unrest in Reykjanes.
- Authors
Maass, Regina; Schippkus, Sven; Hadziioannou, Céline; Schwarz, Benjamin; Jousset, Philippe; Krawczyk, Charlotte
- Abstract
In this study, we measure seismic velocity variations during two cycles of crustal inflation and deflation in 2020 on the Reykjanes peninsula (SW Iceland) by applying coda wave interferometry to ambient noise recorded by distributed dynamic strain sensing (also called DAS). We present a new workflow based on spatial stacking of raw data prior to cross‐correlation which substantially improves the spatial coherency and the time resolution of measurements. Using this approach, a strong correlation between velocity changes and ground deformation (in the vertical and horizontal direction) is revealed. Our findings may be related to the infiltration of volcanic fluids at shallow depths, even though the concurrent presence of various processes complicates the reliable attribution of observations to specific geological phenomena. Our work demonstrates how the spatial resolution of DAS can be exploited to enhance existing methodologies and overcome limitations inherent in conventional seismological data sets. Plain Language Summary: In 2020, an intense unrest period took place on the Reykjanes peninsula, in southwest Iceland, preceding the Fagradalsfjall volcano eruption in 2021. The unrest was characterized by ground movements of several centimeters (measured by GNSS stations) and accompanied by an increased number of local earthquakes. We investigate whether the unrest affects velocities of seismic waves that propagate through the crust in Reykjanes. Instead of conventional seismometers, we use seismic data recorded by a fiber optic cable. This technology has the advantage that measurements can be made every few meters along the cable. We exploit this high spatial sampling to improve methods traditionally applied to seismometer records. These improvements enable us to infer seismic velocity changes as a function of time and space along the fiber optic cable. We detect velocity changes that strongly correlate with the observed ground deformation in Reykjanes and are, therefore, likely linked to the unrest and/or its associated processes. Key Points: Using distributed dynamic strain sensing (also called DAS) and coda wave interferometry, we resolve velocity changes in time and spaceWavelength‐dependent spatial stacking of raw data prior to cross‐correlation improves the spatio‐temporal coherency of resultsInferred velocity changes correlate with vertical and horizontal ground deformation observed during the 2020 unrest period in Reykjanes
- Subjects
ICELAND; SEISMIC wave velocity; SEISMIC waves; FIBER optic cables; SURFACE waves (Seismic waves); VOLCANIC eruptions; GLOBAL Positioning System; FUNCTION spaces
- Publication
Journal of Geophysical Research. Solid Earth, 2024, Vol 129, Issue 6, p1
- ISSN
2169-9313
- Publication type
Article
- DOI
10.1029/2023JB028320