Séminaire ISTerre

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

mercredi 11 mars 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.

Equipe organisatrice : Organisation labo

Séminaire uniquement en visio

Informations de visio :

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

“Minimalist seismology”: studying earthquakes with sparse instrumentation

jeudi 17 septembre 2026 - 11h00

Mathieu Causse - ISTerre

Equipe organisatrice : Organisation labo

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

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Stable‑to‑dynamic expansion of fault slipping area through fluid injection observed in laboratory experiments using a sub‑meter scale specimen

vendredi 18 septembre 2026 - 14h00

Takatoshi Ito  - Université de Tohoku, Japan

Equipe organisatrice : Mécanique des failles

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

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Tectonics, Mantle Dynamics and Coupled Lithosphere-Mantle-Core Evolution of Earth and Other Rocky Worlds

jeudi 24 septembre 2026 - 11h00

Paul Tackley - ETH Zurich

Equipe organisatrice : Grands Séminaires ISTerre

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

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Tectonics, Mantle Dynamics and Coupled Lithosphere-Mantle-Core Evolution of Earth and Other Rocky Worlds

jeudi 24 septembre 2026 - 11h00

Paul Tackley - ETH Zurich

Equipe organisatrice : Grands Séminaires ISTerre

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

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Apport des expériences analogiques pour la modélisation et le suivi en temps réel de la propagation du magma en profondeur : Exemple du Rift Est Africain

jeudi 1er octobre 2026 - 11h00

Virginie Pinel - ISTerre

Equipe organisatrice : Organisation labo

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

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A t-on encore besoin de plaques pour expliquer la tectonique de la vallée du Rhône et des Alpes Occidentales ?

vendredi 2 octobre 2026 - 11h00

philippe VERNANT - Geosciences Montpellier

Equipe organisatrice : Tectonique active et sismicité

Salle Dolomieu, Maison des Géosciences, 38400 Saint Martin d'Hères

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TBA

vendredi 2 octobre 2026 - 14h00

Hugo Boulze - 

Equipe organisatrice : Cycle sismique et déformations transitoires

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

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TBA

vendredi 9 octobre 2026 - 11h00

Eric Beaucé - ISTerre

Equipe organisatrice : Cycle sismique et déformations transitoires

Salle Dolomieu, Maison des Géosciences, 38400 Saint Martin d'Hères

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TBA

vendredi 20 novembre 2026 - 11h00

Farzaneh Mohammadi - ENS Paris

Equipe organisatrice : Cycle sismique et déformations transitoires

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

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