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From Satellites to Soil Response: Analyzing Body Wave Velocity Variations at Shallow Depths in Sync With Satellite Soil Moisture

Description: 

Several recent studies have shown that the cyclicity of meteorological seasons is imprinted as time variations in the velocity of shear waves, V_S, at shallow depths. This has been known for decades from laboratory tests but has only recently been verified using actual earthquake records. However, this dependence has not been sufficiently studied to understand its implications for geotechnical soil characterization or even soil response during earthquake shaking. In this direction, we study 1218 earthquake records from the ARGONET vertical array of accelerographs located on the Island of Cephalonia, Greece. The data, which are publicly available at https://argonet-kefalonia.org/data/argonet_data/, cover the period from June 2015 to October 2022, i.e., they are distributed over more than seven complete hydrological cycles. We apply the method of seismic interferometry by deconvolution to study the variations of both V_S and P wave velocity values (V_P) at different depth intervals corresponding to different station pairs of the vertical array. We compare results with satellite soil moisture data from the Soil Moisture Active Passive (SMAP) mission of the National Aeronautics and Space Administration (NASA), and with data from the European Centre for Medium-Range Weather Forecasts (ECMWF) in the framework of Copernicus Climate Change Service. The accuracy of the satellite soil moisture data for such a site-specific analysis is verified by comparisons with in-situ data from the meteorological and soil moisture monitoring stations of the ARGONET infrastructure. Our results confirm the already known seasonal variation of V_S and show a similar pattern for V_P, which is inversely correlated with the amount of water in the shallow soil layers. Satellite soil moisture data are found to be highly comparable to in-situ measurements, which is particularly encouraging for using them to study the interactions between meteorological factors and soil response during earthquake shaking not only at regional, but also at local scales.

Session: From Earthquake Recordings to Empirical Ground-Motion Modelling - I

Type: Oral

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Zafeiria

Student Presenter: No

Invited Presentation: 

Authors