EGU22-10273
https://doi.org/10.5194/egusphere-egu22-10273
EGU General Assembly 2022
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Temporal Seismic Velocity Changes Associated with the Mw 6.1, 2008 Ölfus Earthquake Doublet, South Iceland, Using Ambient Noise

Yesim Cubuk Sabuncu1, Kristín Jónsdóttir1, Þóra Árnadóttir2, Corentin Caudron3, Thomas Lecocq4, and Aurelien Mordret5
Yesim Cubuk Sabuncu et al.
  • 1Icelandic Meteorological Office , Iceland
  • 2Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Iceland
  • 3Free University of Brussels, Belgium
  • 4Royal Observatory of Belgium, Belgium
  • 5Institut des Sciences de la Terre (ISTERRE), France

Our study presents temporal seismic velocity changes (dv/v) associated with the May 2008 Ölfus earthquakes by computing the cross-correlations of ambient noise. The 2008 Ölfus doublet (M5.8 and M5.9, with a composite magnitude of M6.1) occurred in the South Iceland Seismic Zone, which is a highly active transform zone that accommodates plate motion with major earthquake sequences (e.g., 1896, 1912, 2000). We investigate co-seismic and post-seismic response of the crust in the epicentral area, to the 2008 Ölfus doublet. For our analysis, we used three-component continuous data from three stations of the SIL national seismic network operated by the Icelandic Meteorological Office. Using the MSNoise software package (http://www.msnoise.org), we calculated single station ambient noise cross-correlations and utilized the stretching approach to quantify relative seismic velocity variations. We found the highest co-seismic velocity decrease (<1 percent) in the high-frequency band (1-3 Hz) at a seismic station located 10 km from the rupture zone. The co-seismic dv/v drop is also observed at stations 35 km away from the earthquake epicenter, though the amplitude of the variation is less, at 0.5 percent. We identify three months of post-seismic period in both the high-frequency and low-frequency calculations, indicating the recovery process at different crustal depths after the mainshocks. We compare our dv/v time series to continuous GPS observations, local seismicity, and volumetric stress changes. Our analysis suggests that the velocity changes are mainly controlled by shaking-induced damage. Our findings provide considerable insights into the time-dependent seismic velocity changes caused by the 2008 Ölfus events. This work is supported by the IS-NOISE project (https://is-noise.earth/) and the Icelandic Research Fund, Rannis (https://www.rannis.is/).

How to cite: Cubuk Sabuncu, Y., Jónsdóttir, K., Árnadóttir, Þ., Caudron, C., Lecocq, T., and Mordret, A.: Temporal Seismic Velocity Changes Associated with the Mw 6.1, 2008 Ölfus Earthquake Doublet, South Iceland, Using Ambient Noise, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10273, https://doi.org/10.5194/egusphere-egu22-10273, 2022.