DESSA , J.-X.

In deep offshore, crustal-scale seismic imaging is classically performed by traveltime tomography applied to wide-angle seismic data recorded by a network of Ocean Bottom Seismometers (OBS). The resulting velocity model is of limited resolution. If the wide-angle experiment is multifold thanks to densely sampled OBSs, this large-scale velocity...

The deployment of a worldwide network for infrasound detection requires numerical methods for modeling these signals over long distances. A ray theoretical approach appears robust and efficient. It furthermore allows a straightforward interpretation of recorded phases. We have developed a three-dimensional Hamiltonian ray tracing for modeling...

We present the acquisition and processing of a multi-offset ultrasonic tomography experiment in which we aim to precisely reconstruct the image and kinematic properties of two scatterers that contrast strongly with the water background. The resultant non-linearity causes the failure of a frequency-domain waveform fitting strategy for retrieving...

In offshore surveys, the deep crust is generally investigated by traveltime tomography applied to sparse ocean bottom seismometer data. The inferred velocity models are of limited resolution precluding a quantitative analysis of deep tectonic discontinuities. If dense arrays of ocean bottom seismometers can be deployed, the resulting data sets...

Geophysical Research Letters, v. 31, p. L20106, 2004. http://dx.doi.org/10.1029/2004GL020514

Geophysical Research Letters, v. 30, n. 15, p. 1814, 2003. http://dx.doi.org/10.1029/2003GL017581

Geophysical Research Letters, v. 31, n. 18, p. L18606, 2004. http://dx.doi.org/10.1029/2004GL020453

Journal of Geophysical Research, v. 109, p. B02111, 2004. http://dx.doi.org/10.1029/2003JB002689

Forearc tectonics at accretionary convergent margins has variously been studied using analogue and numerical modelling techniques. Numerous geophysical investigations have targeted the subsurface structure of active forearc settings at convergent margins. However, several critical details of the structure, mode of tectonic evolution and the...

The 26 December 2004 Sumatra earthquake (Mw = 9.1) initiated around 30 km depth and ruptured 1300 km of the Indo‐Australian–Sunda plate boundary. During the Sumatra‐OBS (ocean bottom seismometer) survey, a wide‐angle seismic profile was acquired across the epicentral region. A seismic velocity model was obtained from combined travel time...

Current models predict that the seismogenic zone along subduction thrusts, where the largest earthquakes nucleate and propagate, does not extend to the forearc mantle below the crust of the upper plate. Stable sliding conditions have been shown to prevail there, particularly along several circum-Pacific margins that underwent great megathrust...

The deep structure of the North Ligurian margin and its contiguous Ligurian basin as well as the seismicity recorded in these zones are neither well understood nor precisely constrained. In order to better address these questions, there is a need for offshore instrumenting, which was realised for a duration of nearly 6 months during the...

The distribution of plate motion between multiple fault strands and how this distribution may evolve remain poorly understood, despite the key implications for seismic hazards. The North Anatolian Fault in northwest Turkey is a prime example of a multistranded continental transform. Here we present the first constraints on late Quaternary slip...