ISTerre seminar

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Spectral evolution of continuous seismo-volcanic signals from a network-based analysis

Wednesday 11 March 2026 - 10h00

Emmanuel Caballero - Earth Sciences New Zealand
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Volcanic systems generate a wide range of seismic signals, including volcano-tectonic earthquakes, long-period events, and volcanic tremors. Each signal is associated with a specific physical mechanism, exhibits distinct temporal characteristics, and occurs at different stages of volcanic activity. Despite extensive characterization of these signals, the processes governing their generation and temporal evolution remain incompletely understood. Network-based approaches provide a powerful framework to investigate volcanic systems by integrating information from multiple stations simultaneously. In this study, we analyze ten years (2013–2023) of continuous seismic data from Piton de la Fournaise (La Réunion, France) and two years (2015–2016) from the Klyuchevskoy volcanic group (Kamchatka, Russia). We apply a method based on the spectral covariance matrix computed from interstation single-component cross-correlations. By estimating the width of the eigenvalue distribution, we quantify the number of independent seismic sources contributing to the continuous wavefield. The resulting spectral-width distributions reveal that continuous signals are characterized by multiple narrow spectral peaks, observed not only during co- eruptive tremor episodes but also during periods without visible surface activity. To better characterize these persistent features, we introduce a normalization procedure that enhances spectral peaks in both the frequency and time domains. We identify numerous stable spectral lines in the 1–3 Hz band that remain nearly constant over time scales ranging from weeks to months. In parallel, clear differences emerge between co- eruptive and quiescent periods, with significant spectral variations occurring during long- lasting eruptions. The spatial distribution of these signals suggests a dominant contribution from internal volcanic processes, with observed differences likely reflecting medium changes within the edifice.

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Organizing team : Organisation labo

Séminaire uniquement en visio

Informations de visio :

https://univ-grenoble-alpes-fr.zoom.us/j/96224562172?pwd=U9qy51brNFjsrfZeaH0PH4rbqSHjY2.1