ISTerre - Institut des Sciences de la Terre

ANR project SSDYN (2022 - 2025)

Mathilde RADIGUET — 2023-04-06T21:11:19Z

News

August, 2023: Zaccaria El Yousfi 's paper on short-term slow slip and intermittence during large-slow slip is now online at EPSL: https://doi.org/10.1016/j.epsl.2023.118340. El Yousfi Z., Radiguet M., Rousset B., Husker A., Kazachkina E., Kostoglodov V. 2023. Intermittence of transient slow slip in the Mexican subduction zone. Earth Planet. Sci. Lett. 620, 118340
April 20th, 2023: Zaccaria El Yousfi will present his PhD results at 2023 SSA meeting: Intermittence of Transient Slow Slip in the Mexican Subduction Zone, as Seen by Tectonic Tremors.
October 18th, 2022: ANR Kick-off meeting

Project Objectives

The main objective of this project is to gain knowledge about aseismic slip processes on a large spectrum of spatial and temporal scales. We combine seismic and geodetic data to capture details of slow slip dynamics. The project focusses on the Mexican subduction zone, an ideal and almost unique natural laboratory to study these processes, thanks to the suitable plate geometry (short trench to coast distance, flat slab) and the great variety of the slow slip processes observed.

Study Area

This project combines a large-scale target (left map below), in which we plan to analyze the various slow slip processes over this large plate boundary, to constrain their processes and characterize the interactions; and a small scale target in the Oaxaca region (right map below)) in which a denser instrumentation will allow to decipher the details of slow slip dynamics.

Geodynamic context, previously identified events and available data. (A) Large scale map of the Mexican subduction with major earthquakes (gray), SSEs (blue) and tremors (green). GNSS stations (blue triangles), broadband seismic stations from SSN (red triangles) and Descending Sentinel-1 tracks are represented. Past SSEs and tremors have been identified in Guerrero and Oaxaca. Tremors also occur in Jalisco, Colima and Michoacán, but so far not associated with detectable SSEs. At this scale we will rely on GNSS stations (blue triangles), broadband seismic station from SSN (red triangles) and InSAR (shown are Descending Sentinel-1 tracks) for our analysis. (B) Zoom on the Oaxaca region where a large tremor area is located slightly downdip from the mai SSE region. The three additional seismic stations (big orange triangles) will be installed to monitor tremors, in addition with 20 new GNSS sites installed by UNAM (filled blue triangles).

People Involved

PhD, Students, Postdocs:

Zaccaria El Yousfi (PhD 2022-2025)
Aimine Meridi (Master 2 internship, 2023)

Permanent:

Mathilde Radiguet (PI)
E. Pathier (Ass. professor at ISTerre, Grenoble), InSAR expert.
P. Poli (University of Padova), seismologist (exploration of continuous seismic for fault monitoring)
A. Walpersdorf (Professor at ISTerre, Grenoble), expert in GNSS geodesy.
V. M. Cruz-Atienza (professor at UNAM (Mexico)), seismology (physics of earthquake source, slow earthquake processes). Scientific coordinator for Mexico.
V. Kostoglodov (professor at UNAM), geophysics and geodesy.
J. Tago (professor at UNAM), geomodeler and applied mathematician.
E. Kazachkina research Engineer at UNAM, Field instrumentation and GNSS processing.
E. Kazachkina (Researcher at IGN and IPGP, Paris, France): geodesy and geophysics, non-tectonic deformation signals.
B. Rousset (researcher ITES, Strasbourg, France): geodesy and time series analysis.
A. Gualandi (researcher at INGV , Rome, Italy): geophysics and specialist in source separation.

Tom Winder-"Crustal stress changes in Iceland's Northern Volcanic Zone observed with noise interferometry and microseismicity"

Mathilde RADIGUET, Virginie PINEL — 2019-06-28T15:20:37Z

Séminaire de l'équipe Géophysique des volcans & géothermie

par Guillermo Cortés- Universita degli Studi di Udine ,Italie

– Date
4 juillet 2019 à 10h00

– Lieu
Salle Paul Gidon, ISTerre Chambéry

Seismic and aseismic behavior of fault zones : influence of the coupling between fault slip and the conjointly evolving medium

Anaïs SCHNEIDER, Mathilde RADIGUET — 2019-04-29T09:28:51Z

– Pas de vidéo disponible pour ce séminaire.

Geophysical data have documented the high spatial and temporal variability of fault slip modes. In the seismogenic depth range, slip rate on faults span a continuum ranging from mm/yr to m/s . Yet, the physics of the processes that control these behaviors remains poorly understood. This severely limits our ability to assess the potential size, magnitude and recurrence of earthquakes on active faults. The research approach undertaken tends to cut across traditional disciplinary bounds and promote multidisciplinary studies using field observations, geodetic measurements, laboratory experiments as well as numerical studies to better understand the evolution of fault zone properties and associated processes occurring during fault slip. We will discuss the importance of taking into account the main fault plane and the surrounding medium as a continuously evolving coupled system to highlight what controls seismic and aseismic slip and better assess seismic hazard.

Preservation of traces of life under extreme environments mimicking ancient conditions on Mars

Anaïs SCHNEIDER, Mathilde RADIGUET — 2018-10-16T10:50:23Z

– Pas de vidéo disponible pour ce séminaire.

The interaction between microbial communities and the geosphere produce several natural entities such as structures and compounds that can be eventually transferred to the geological record in a span of time up to billions of years. They provide essential information in regards to the microbial life which generated them as a result of metabolism (geochemical as mineral and, isotopic) or phylogenetic origin (molecular biomarkers). If life emerged on Mars and assuming that it is founded on the same principles as the Terrestrial life, it may have recorded as similar geobiological traces occurring in the different earthy geological materials. In this regard, the geological record of Mars strongly suggests that most of the ancient, as well as some modern environments, are characterized as extreme systems under terrestrial conditions. As a consequence, the preservation of ancient biological activity in Mars can be evaluated by studying the preservation of the geobiological record in terrestrial analogs replicating the conditions on the red planet. In this seminar, we will discuss different types of biosignatures that have been preserved in some terrestrial analogs of Mars. This will include mineral, structural/textural, geochemical and molecular traces that have been found in acidic, cryptic and hyperarid environments. In some cases, biosignatures have found not only in modern and active extreme environments but also in its geohistoric counterparts that have been recorded as distinctive geological materials.

L'effet "reine rouge" : l'économie face aux contraintes physiques et énergétiques d'un monde aux dimensions finies

Anaïs SCHNEIDER, Mathilde RADIGUET — 2018-09-20T13:47:52Z

– Vidéo disponible sur https://www.youtube.com/watch?v=n3LyVbGUFu4
(Pour la vidéo, merci à Emmanuel Prados, chercheur INRIA, équipe STEEP et organisateur du cycle de conférences "Comprendre et Agir")

Il s'agira d'exposer quelques uns des enjeux d'une réinscription de l'économie dans le cadre général posé par les contraintes matérielles et thermodynamiques, macro-économiques et historiques. Gaël Giraud discutera l'intérêt de ces enjeux pour le développement durable et la contribution de la France à l'Aide publique au développement.

Mars, le 1er milliard d'années

Anaïs SCHNEIDER, Jérôme WEISS, Laurent HUSSON, Mathilde RADIGUET — 2018-09-20T13:26:55Z

– Pas de vidéo disponible pour ce séminaire.

Après plus de 50 ans d'exploration, la planète Mars n'arrête pas de surprendre. Retour sur les dernières découvertes, entre écoulement d'eau liquide actuel et grand basculement de la planète. La planète Mars a basculé voici 3 à 3,5 milliards d'années. Et c'est un vaste édifice volcanique, le plus grand du système solaire, qui en est la cause. Par sa masse hors du commun, le dôme volcanique de Tharsis a entraîné la rotation de la croûte et du manteau de Mars sur son noyau. Ce changement radical renouvelle de façon profonde l'histoire primitive de Mars et les liens entre dynamique interne, activité volcanique, tectonique et évolution climatique.

– Version PDF

14-18 : tremblements de guerre. Les géologues montent au front

Anaïs SCHNEIDER, Mathilde RADIGUET — 2018-09-20T13:26:45Z

– Pas de vidéo disponible pour ce séminaire.

- Archives et Podcasts

L'effet de serre : sa découverte, sa compréhension et les effets de ses variations sur la température de la Terre

Anaïs SCHNEIDER, Mathilde RADIGUET — 2018-09-20T13:26:37Z

– Pas de vidéo disponible pour ce séminaire.

La température de surface de la Terre, et de façon plus générale le climat de la Terre, sont le résultat d'un ajustement entre l'énergie reçue et celle perdue. En conséquence, toute modification de ce bilan d'énergie peut entraîner une modification du climat. Nous présenterons tout d'abord comment cette problématique s'est progressivement mise en place à partir du milieu du 19e siècle, comment l'importance des variations de l'ensoleillement et de l'effet de serre ont été rapidement identifiées. Nous détaillerons ensuite l'analyse physique de l'effet de serre, comment une certaine complexité et quelques paradoxes peuvent se cacher sous cette appellation simple, comment cet effet peut-être quantifié, observé et calculé. Nous détaillerons cette analyse pour la vapeur d'eau et le CO2, les deux principaux contributeurs à l'effet de serre. Enfin, nous terminerons en montrant que les premières estimations de l'effet de serre dû au CO2 réalisées par Arrehnius en 1896, bien que proches des estimations actuelles, sont le résulat de la compensation de plusieurs grosses erreurs et sont donc totalement fortuites.

Water and Tides Modulate Deformation, Seismicity and Tremor in California

Anaïs SCHNEIDER, Mathilde RADIGUET — 2018-06-04T19:51:13Z

– Pas de vidéo disponible pour ce séminaire.

Establishing what controls the timing of earthquakes is fundamental to understanding the nature of the earthquake cycle and critical to determining time-dependent earthquake hazard. Seasonal loading provides a natural laboratory to explore the crustal response to a quantifiable transient force. In California, the accumulation of winter snowpack in the Sierra Nevada, surface water in lakes and reservoirs, and groundwater in sedimentary basins follow the annual cycle of wet winters and dry summers. The surface loads resulting from the seasonal changes in water storage produce elastic deformation of the Earth's crust. We use vertical GNSS displacement time series to constrain models of monthly water loading and compute the resulting stress changes on fault planes of small earthquakes. Additionally, we model the seasonal stress changes for tidal, thermal, and atmospheric loading sources with annual periods to produce an aggregate stressing history for faults in the study area. We find the hydrological loads are the largest source of seasonal stresses and produce resolvable modulation of micro-seismicity. While much shorter-period diurnal and semi-diurnal stress cycles fail to substantially modulate upper crustal seismicity, they dramatically influence the timing of tremors on the lower-crustal extension of the San Andreas fault. Near-lithostatic fluid pressure allows tidal stresses to dominate the timing of low-frequency earthquakes and associated slow slip deep in the roots of the fault.

– Version PDF

Cratering-induced magmatism on the Moon

Anaïs SCHNEIDER, Mathilde RADIGUET — 2018-05-15T07:09:52Z

– Pas de vidéo disponible pour ce séminaire.

On the Moon and other terrestrial planets with no plate tectonics, volcanic deposits and evidence of shallow magmatism are often located within impact craters, called floor-fractured craters (FFCs). It is known that large impact craters may induce volcanism and secondary crust formation, but what is the link between small impact craters, that are much more frequent, and magmatic activity ? Using quantitative observations on lunar FFCs and physical models of magma flow and emplacement, I will show that surface unloading caused by an impact crater allows for magma ascent in the crust, magmatism and, thereby, crustal evolution. Magmatisme induit par cratérisation sur la Lune. Sur la lune, comme sur d'autres planètes terrestres ne présentant pas de tectonique des plaques, les dépôts volcaniques et évidences de magmatisme sont souvent localisés dans des cratères d'impact, appelés cratères à sol fracturé (FFCs). Il est connu que les bassins d'impact induisent la formation de croûte secondaire, mais quel est le lien entre les petits cratères d'impact, beaucoup plus fréquents, et l'activité magmatique ? En utilisant des observations quantitatives sur les FFCs lunaires et des modèles physiques de mise en place du magma, je montrerai que le déchargement de surface causé par un cratère d'impact permet l'ascension du magma dans la croûte, et, par conséquent, du magmatisme et une évolution de la composition crustale.