Séminaire ISTerre

Maximizing the value of geologic data in seismic hazard assessment

mercredi 31 janvier 2024 - 10h00
Nicolas Harrichhausen - Séminaire post-doc
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Fault source models are integral to seismic hazard assessments, enabling the inclusion of geological data to refine earthquake locations and frequency predictions. Utilizing fault geometry (location, depth, orientation) and slip rates, these models estimate earthquake occurrence rates for specific faults. Geological inputs thus directly influence earthquake rates and the computed hazard in seismic models. Crucially, fault source models incorporate geological data, which provides insights into earthquake magnitudes and frequencies before the era of instrumental monitoring, less than 100 years ago. The inclusion of geological data in probabilistic seismic hazard analysis (PSHA) is acknowledged as important. However, the variable spatial and temporal scales over which slip-rate observations are made is often not fully considered. For example, paleoseismic studies focusing on a single fault strand may overlook off-fault deformation or slip on parallel strands to the fault core. Conversely, rates derived from the entire fault zone, often more than 1 km wide, might include more off-fault deformation, resulting in higher slip rates. I will present my prior research on the Pallatanga-Puna fault zone, demonstrating that using different slip rates leads to significantly varied earthquake rates for the same fault system. This study shows that geodetic and geomorphic slip rates, measured across the fault zone's entire width, produce earthquake rates aligning closely with those from the seismic catalog surrounding the fault zone. This suggests that slip rates including off-fault deformation (the damage zone) better represent the seismogenic potential of a fault. I will then present a research proposal to test these results on fault systems with different kinematics. Additionally, since the width of the damage zone seems important for determining slip rates, I aim to explore how orientations of inherited structures may control off-fault deformation widths. My broad objective is to better constrain the uncertainty of geological data in fault source models, enhancing their effectiveness in seismic hazard assessments.

Equipe organisatrice : Organisation labo

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

“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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