Influence of Seasonal Frozen Soil on High-Frequency Attenuation (κ0)
Description:
When estimating site effects in terms of amplification or attenuation of seismic waves, it is usually assumed that the seismic properties of the ground are constant over time. In recent years, several studies have shown that near-surface shear wave velocities can be subject to a variety of environmental parameters, such as temperature, precipitation or groundwater level, leading to a variation of shear wave velocity with time. Similar observations have been partly made for seismic attenuation, but studies investigating the influence of seasons on seismic attenuation are very limited.
Herein, the parameter κ0 is commonly utilized to describe the site-specific attenuation at high frequencies. We have calculated the difference in κ0 between surface and borehole station pairs of the KiK-net network in the northeastern corner of Hokkaido, Japan. We observe that Δκ0 is almost constant from May to November, but increases rapidly from late November to early January. In January and February, Δκ0 is about 0.05 s higher than in the summer (increased high-frequency attenuation), before returning to its original value between March and April. This observation can be explained by seasonally frozen soils of the upper few tens of centimeters, which add an additional layer of increased shear wave velocity to the geological 1-D velocity model below a station, thus increasing the high-frequency attenuation.
Session: How Well Can We Predict Broadband Site-Specific Ground Motion and Its Spatial Variability So Far? [Poster Session]
Type: Poster
Date: 5/1/2024
Presentation Time: 08:00 AM (local time)
Presenting Author: Marco
Student Presenter: No
Invited Presentation:
Authors
Annabel Haendel Corresponding Author ahaendel@gfz-potsdam.de GFZ Potsdam |
Marco Pilz Presenting Author pilz@gfz-potsdam.de GFZ Potsdam |
Fabrice Cotton fcotton@gfz-potsdam.de GFZ Potsdam |
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Influence of Seasonal Frozen Soil on High-Frequency Attenuation (κ0)
Session
How Well Can We Predict Broadband Site-Specific Ground Motion and Its Spatial Variability So Far?