Séminaire ISTerre

An enhanced earthquake catalog of the 2010 Mw 8.8 Maule aftershock sequence using modern tools

lundi 3 février 2025 - 14h00
Rodrigo Flores Allende - IPGP
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Understanding rupture mechanisms, seismicity propagation, distribution, and migration after a major earthquake relies on the quality of earthquake catalogs, particularly their detection capabilities, location accuracy, and magnitude completeness. On February 27, 2010, a Mw 8.8 earthquake struck the Maule region in south-central Chile, causing widespread damage and substantial loss of life. As the largest well-instrumentally recorded earthquake in Chile, this event offers a unique opportunity to revisit an old dataset, refine the aftershock sequence analysis, and gain deeper insights into subduction zone dynamics. Here we analyze ~10 months of continuous seismic data from the International Maule Aftershock Deployment (IMAD), a temporary network with about 156 stations deployed throughout the rupture zone. Using the recent Back-Projection and Matched Filtering (BPMF) workflow, which integrates PhaseNet, a deep-learning-based phase picker, we detected more than 100,000 earthquakes with at least 10 P and S-wave arrival phases. We relocated these events using NonLinLoc-SSST-Coherence, a probabilistic algorithm. A subset of them served as templates for template matching, producing a final catalog of about 375,000 events. This represents nearly a ninefold increase in detected events compared to prior catalogs and achieves a magnitude of completeness of Mw ~1.7, lowering it by over one order of magnitude. Our catalog significantly enhances the spatio-temporal resolution, revealing intricate seismic structures (e.g., fault geometries) and dynamic post-seismic activity. Our improved relocations draw these key features, including the shallower seismic zone in the Pichilemu-Vichuquén region (33.5°S–35°S) and deeper seismic clusters near Concepción (37°S–38°S) in unprecedented detail. Temporal b-value variations (0.8–1.1) reveal zones of high-stress accumulation and the activation of multiple fault systems, highlighting the heterogeneous nature of post-seismic deformation. This high-resolution dataset underscores the potential of modern methodologies and algorithms, unveiling features from older data with improved clarity and detail.

Equipe organisatrice : Cycle sismique et déformations transitoires

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

Informations de visio :

https://univ-grenoble-alpes-fr.zoom.us/j/92956342169?pwd=atRbmXkR3hcDaXyMw5rsnD8AbkUqdG.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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