Correlation between seismic attenuation and S-wave velocity in the volcanic region of Reykjanes, Iceland

In volcanic areas, seismic attenuation is greatly influenced by the presence of hot rocks and magma. This makes the spatial distribution of attenuation highly inhomogeneous and three-dimensional. The attenuation model can be expressed in terms of the attenuation coefficient α or the quality factor Q, both of which depend on the frequency of seismic waves. Hot rocks and magma affect especially S-wave propagation very strongly. In addition to attenuation, the S-wave velocity and the ratio of P-wave and S-wave velocities also change significantly.

To find the relationship between seismic S-wave attenuation and S-wave velocity, we studied the Reykjanes Peninsula region in SW Iceland, where intense volcanic activity has been ongoing since 2019. This area is monitored by the local seismic network REYKJANET, which consists of 17 stations. We have used 8602 seismic rays that link 680 earthquake foci to the Reykjanet stations. We determined the average value of the α and Q attenuation parameters as a function of frequency. We also determined the average seismic velocities vp and vs along these rays. We calculated the correlation between attenuation and seismic velocities. It turns out that there is a statistically significant dependence between these parameters.

The findings can be used to map the occurrence of magma in the upper crust in volcanic regions and thus contribute to the prediction of volcanic eruptions.