Magali Riesner

Centre Européen de Recherche et d’Enseignement des Géosciences de l’Environnement | CEREGE · Earth and Planets

The NE‐dipping Anghiari normal fault (AF), bounding to the west the Sansepolcro basin in the Upper Tiber Valley (northern Apennines), is thought to be a synthetic splay of the Altotiberina (ATF) low‐angle normal fault (LANF), an active ENE‐dipping extensional detachment whose seismogenic behavior is debated. In order to assess the Anghiari fault ca...

Large earthquakes breaking the frontal faults of the Himalayan thrust system produce surface ruptures, quickly altered due to the monsoon conditions. Therefore, the location and existence of the Mw8.3 1934 Bihar–Nepal surface ruptures remain vividly disputed. Even though, previous studies revealed remnants of this surface rupture at the western end...

The 2019-11-1, Mw4.9 Le Teil earthquake occurred within the NE termination of the Cévennes faults system (CFS) in southern France, along the La Rouvière fault (LRF), an Oligocene normal fault which was not known to be potentially active. This shallow moderate magnitude reversefaulting event produced a 5 km-long surface rupture and strong ground sha...

The largest (M8+) known earthquakes in the Himalaya have ruptured the upper locked section of the Main Himalayan Thrust zone, offsetting the ground surface along the Main Frontal Thrust at the range front. However, out-of-sequence active structures have received less attention. One of the most impressive examples of such faults is the active fault...

Unravelling relations between lateral variations of mid-crustal seismicity and the geometry of the Main Himalayan Thrust system at depth is a key issue in seismotectonic studies of the Himalayan range. These relations can reveal along strike changes in the behavior of the fault at depth related to fluids or the local ramp-flat geometry and more gen...

The Andes are the modern active example of a Cordilleran-type orogen, with mountain-building and crustal thickening within the upper plate of a subduction zone. Despite numerous studies of this emblematic mountain range, several primary traits of this orogeny remain unresolved or poorly documented. The onset of uplift and deformation of the Frontal...

The Andes are the modern active example of a subduction-type orogen, with mountain-building and crustal thickening within the upper plate of a subduction zone. Despite numerous studies of this emblematic mountain range, several primary traits of this orogeny remain unresolved or poorly documented. The onset of uplift and deformation of the Frontal...

The largest (M8+) known earthquakes in the Himalaya are documented to have ruptured the upper locked segment of the Main Himalayan Thrust zone, producing slip at the surface along the Main Frontal Thrust. However, out-of-sequence active structures have received less attention. Here, we focus on an active fault that generally follows the surface tra...

The largest (M8+) known earthquakes in the Himalaya have ruptured the upper locked segment of the Main Himalayan Thrust zone, producing slip at the surface along the Main Frontal Thrust at the range front. This active deformation has been well documented, with an emphasis on the more accessible central and eastern Nepal. However, out-of-sequence ac...

West-verging thrusts, synthetic with the Nazca - South America subduction interface, have been recently discovered at the western front of the Andes. At ~33°30’S, the active San Ramón fault stands as the most frontal of these west-verging structures, and represents a major earthquake threat for Santiago, capital city of Chile. Here we elaborate a d...

The Andean belt is the only present-day active case example of a subduction-type orogeny. However, an existing controversy opposes classical views of Andean growth as an east-verging retro-wedge, against a recently proposed bi-vergent model involving a primary west-vergent crustal-scale thrust synthetic to the subduction. We examine these diverging...

The Andean belt is the only present-day active case example of a subduction-type orogeny. However, an existing controversy opposes classical views of Andean growth as an east-verging retro-wedge, against a recently proposed bi-vergent model involving a primary west-vergent crustal-scale thrust synthetic to the subduction. We examine these diverging...

Developing 3D representations of active faults is an important step to improve seismic-hazard assessment. However, the geom-etries of faults can be difficult to constrain at depth, and building representations is often subjective. We present a new objective workflow to build 3D fault geometries from surface and subsurface data that are generally av...

West-verging thrusts, synthetic with the Nazca - South America subduction interface, have been recently discovered at the western front of the Andes. At ~33°30’S, the active San Ramón fault stands as the most frontal of these west-verging structures, and represents a major earthquake threat for Santiago, capital city of Chile. Here we elaborate a d...

The Andes, one of the most significant reliefs on Earth, is the case example of a subduction-type mountain belt. In central Chile and western Argentina, the particular east-vergent structure of the Aconcagua fold-and-thrust belt (AFTB) is found atop a huge basement high with elevations > 4000 m, the Frontal Cordillera. Classical conceptual models c...

The Andes-Altiplano orogenic system, one of the most significant topographic feature on Earth, is the case example of subduction-type mountain belts. This latter conceptual model considers that the overall structure of the mountain belt forms antithetic to the subduction zone which marks the main plate interface, and as such poses several mechanica...

We present a new three-dimensional velocity model of the crust and upper mantle for the eastern margin of the Tibetan Plateau, developed using the concept of a Community Velocity Model (CVM) (Magistrale et al., 2000; Süss and Shaw, 2003). The model extends from 27.5°-34.5°N and 100°-110°E, and describes the velocity structure of the Sichuan basin a...