REACTIVE: Climate Signals in Seismic Site Response

At Geoscience Bucharest 2025 (30-31 October), REACTIVE researchers presented new insights into how seasonal hydrological processes subtly reshape seismic site response across Romania.

The study "Seasonal Variations Of HV Ratios Of Seismic Noise Across Romania: Insights Into Soil Moisture And Hydrological Loading" shows that ambient seismic noise H/V ratios fluctuate seasonally, with short-term variations strongly correlated with precipitation. Interestingly, resonance frequencies remain stable while amplitudes respond to rainfall, suggesting hydro-mechanical modulation of shallow soils. Surface temperature mirrors seasonal cycles, but near-surface layers (<1 m) may lag by up to a month, revealing complex soil–atmosphere interactions.

In another study currently underway, REACTIVE researchers investigate how hydrological processes influence seismic site response across Romania.

Using continuous ground vibration data from across Romania, the team discovered that

• Peak ground motion changes with rainfall
• Seasonal patterns in soil behavior emerge, especially during summer
• Even subtle shifts in soil stiffness can be detected and modeled

To make sense of these changes, the team will developed hydro-seismo-elastic program that converts rainfall into predictions of how soil properties and ground motion may change over time.

This will help scientists and decision-makers understand how climate-driven rainfall affects the stability of the ground, offering a practical way to assess risk and improve resilience in regions prone to extreme weather.

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