LECLERC , Frédérique

Geodetic measurements reveal modern rates of tectonic deformation along subduction zones, but the kinematics of long-term deformation are typically poorly constrained. We explore the use of submarine coral reefs as a record of long-term coastal vertical motion in order to determine deformation rate and discuss its origins. The Lesser Antilles...

In the past few years, marine geologists have new eyes to capture seafloor in detail! Different types of deep-sea vehicles can now map the sea bed, at resolutions never reached before, and in particular with new imaging techniques. And this is the starting point of the story behind our paper.

The AMORGOS-23 cruise (https://doi.org/10.17600/18003211) was conducted onboard R/V Europe from April 26th 2023 to May 9th 2023. Using HROV Ariane equipped with 4K cameras, we surveyed the main active faults between Amorgos and Anafi islands in order to identify and quantify recent deformation of the seafloor linked to the 1956 Amorgos...

On July 9th, 1956, a Ms 7.8 tsunamigenic earthquake occurred offshore Amorgos and Santorini islands. The causative fault was recently identified offshore Amorgos1, and offset the seafloor by several meters. One secondary structure, branched on the main fault, is cross-cutting the southern coast of Amorgos island2. A ~1-m high ribbon is visible...

Near-bottom multibeam bathymetry and back-scatter data acquired along the Amorgos and Santorini-Amorgos faults, in the Aegean sea. High-resolution bathymetry data (1 m/pixel) were acquired by the autonomous underwater vehicle (AUV) IdefX, deployed during the AMORGOS-22 cruise (https://doi.org/10.17600/18001479) with the MBES EM2040. The dataset...

The AMORGOS-23 cruise (https://doi.org/10.17600/18003211) was conducted onboard R/V Europe from April 26th 2023 to May 9th 2023. We surveyed the coastal and deep areas offshore Amorgos and Anafi islands with the multibeam echosounder ME70, at reduced speed (2-5 kt) in order to acquire data on the very steep fault scarps. Bathymetric data...

The Mediterranean region is exposed to potentially damaging tectonic and tsunami hazards, with Greece representing Europe's most seismically active country. In particular, the Santorini-Amorgos fault system located in the Aegean extending back-arc region (Aegean Sea, Greece) was the scene of the largest earthquake and subsequent tsunami event...

Ship navigation data records are proposed to be complementary information for monitoringoffshore tsunami currents following great earthquakes. Offshore GPS measurements on theresearch vessel Kilo Moana of the University of Hawaii following the 2010 Mw 8.8 Mauleearthquake have illustrated the potential of GPS kinematic positioning solutions,...

International audience

International audience

We present a 1:25,000 scale map of the coseismic surface ruptures following the 30 October 2016 Mw 6.5 Norcia normal-faulting earthquake, central Italy. Detailed rupture mapping is based on almost 11,000 oblique photographs taken from helicopter flights, that has been verified and integrated with field data (>7000 measurements). Thanks to the...

Observations of fault geometry and cumulative slip distribution serve as critical constraints on fault behavior over temporal scales ranging from a single earthquake to a fault's complete history. The increasing availability of high-resolution topography (at least one observation per square meter) from air-and spaceborne platforms facilitates...

The study of normal fault-generated landforms, such as fault scarps, is commonly performed to investigate fault evolution and the recurrence and magnitude of earthquakes. The Amorgos region (Cyclades, Greece), located in the central part of the Aegean Sea, is structured by ~70km large NE-SW normal faults accommodating the back-arc extension of...

Published slip distribution models, based on geodetic, seismological and tsunami data, of the Mw 7.8, 2010 Mentawai tsunami earthquake offshore south-central Sumatra, suggest that the large tsunami wave was generated by a narrow swath of high seafloor uplift along the accretionary wedge front, implying higher vertical throw than that...

International audience

In the Mediterranean Sea, the probability that a large earthquake-triggered tsunami will occur in the coming decades is high. Historical tsunami database informs us on their geographical occurrence but their sources, i.e., the faults that slipped during earthquakes and displaced the seafloor to generate tsunamis, are often unknown. Here we...

Propagation of fault rupture to the seafloor is a likely cause of enhanced tsunami generation during megathrust earthquakes. New, high‐resolution seismic reflection profiles and swath bathymetry collected across the northern limit of the Mw 7.8, 25 October 2010 Mentawai tsunami earthquake rupture reveal significant and systematic lateral...

We present the content and scripting of an active tectonic lab session conceived for third-year undergraduate students studying Earth sciences at Observatoire des Sciences de l'Univers in Lyon. This session is based on a research project conducted on the submarine Roseau active fault in the Lesser Antilles. The fault morphology is particularly...

The short and heavy rainfall events observed on the French Riviera often lead to flash floods on coastal catchments: during the flood of 2 October 2015, a peak discharge between 185 and 295 m3/s was estimated on the Brague at Biot at 8:00 PM, whereas the flow rate was about 1 m3/s at 5:30 PM there. While measurements of such discharges are very...

International audience

Short and heavy rainstorm events often lead to flash floods on the French Riviera coastal catchments: during the historical 2nd October 2015 flood, a peak streamflow value between 185 and 295 m3/s was estimated on the Brague River at Biot at 10:30 P.M., while the streamflow was around 1 m3/s at 6:30 P.M. at the same section. If the measurements...

International audience

International audience

Faults form dense, complex multi‐scale networks generally featuring a master fault and myriads of smaller‐scale faults and fractures off its trace, often referred to as damage. Quantification of the architecture of these complex networks is critical to understanding fault and earthquake mechanics. Commonly, faults are mapped manually in the...

Eruptive activity shapes volcanic edifices. The formation of broad caldera depressions is often associated with major collapse events, emplacing conspicuous pyroclastic deposits. However, caldera subsidence may also proceed silently by magma withdrawal at depth, more difficult to detect. Ambrym, a basaltic volcanic island, hosts a 12-km wide...