ISTerre seminar

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Monitoring temporal variations in seismic velocity and site response across different depth intervals at the Wildlife Liquefaction Array

Tuesday 25 November 2025 - 11h00

Jianye Zong - Chengdu University of Technology (China)
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The uppermost tens of meters of the subsurface are widely utilized by humans. Monitoring the seismic properties of shallow subsurface materials can provide valuable information for hazard assessment and infrastructure design. Seismic velocity, which is easier to measure, reflects the stress state of the shallow subsurface. Site effect indicates ground motions amplified by the low impedance of shallow subsurface. These seismic properties show variations with tectonic and environmental factors. We take advantage of 4-year-long borehole ambient noise data, recorded by the Wildlife Liquefaction Array, which can better constrain the depth range, to investigate the depth-dependent temporal variations of seismic properties. Overall, the measurements reveal two patterns. One is relatively large, instantaneous changes that could be associated with strong earthquakes or others. The other is moderate, seasonal variations that possibly be affected by environment factors. Meanwhile, the temporal variations are depth-dependent. Using environment data (daily temperature and precipitation) recorded by a nearby meteorological station, we forward-model seismic velocity variations driven by environmental effects. Our results highlight depth-dependent temporal variations of seismic properties, which warrant greater attention in hazard prevention efforts.

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Organizing team : Ondes et structures

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

Informations de visio :

https://univ-grenoble-alpes-fr.zoom.us/j/95496607088?pwd=UuSVyVX0SCxaFwJ8BOzQujEfEjydwi.1