Dominique Gibert

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Electric potential has been monitored since December 2003 in the roots and at two circumferences and one vertical profile in a standing poplar (Populus nigra). Electric potential is sampled using 6 mm diameter stainless steel rods, inserted 5 mm deep in the sapwood and is referenced to an unpolarisable lead/lead chloride electrode installed 80 cm deep in(More)
We analyze interfaces by using reflected waves in the framework of the wavelet transform. First, we introduce the wavelet transform as an efficient method to detect and characterize a discontinuity in the acoustical impedance profile of a material. Synthetic examples are shown for both an isolated reflector and multiscale clusters of nearby defects. In the(More)
Wa,velet a,na,lysis is a.pI•lied to detect a.nd cha, ra.cte,'ize singula, r events, or singula, rities, or jerks, in the time series ,,•a,de of the last centu,-y monthly mean values of the east component of the geomagnetic field fi'om Europea, n observa.tories. After choosing a, wel!-a,da,pted wavelet function, the analysis is first performed on synthetic(More)
A method is proposed to find the digital input signals to enter in nonlinear acoustical systems (power amplifiers, transducers, etc.) in order to obtain desired arbitrary response signals. The searched input signals are found by performing a Monte Carlo search guided by a simulated annealing process applied to a hidden model with a small number of(More)
[1] Electrical impedance tomography aims to recover the electrical conductivity underground from surface and/or borehole apparent resistivity measurements. This is a highly nonlinear inverse problem, and linearized inverse methods are likely to produce solutions corresponding to local minima of the misfit function to minimize. In the present paper,(More)
The Soufrière of Guadeloupe lava dome consists of several 3D domains of relatively unaltered massive andesite separated by major radial fractures that reach at least up to about half of the dome's height. More than 20,000 geo-electrical measurements made on the top and the flanks of the lava dome are used to construct the first geophysical image of the(More)
We consider some practical issues of the determination of the b-value of sequences of magnitudes with the bootstrap method for short series of length L and various quantization levels Dm of the magnitude. Preliminary Monte Carlo tests performed with Dm 1⁄4 0 demonstrate the superiority of the maximum likelihood estimator bMLE, and the inconsistency of the,(More)
Catastrophic collapses of the flanks of stratovolcanoes constitute a major hazard threatening numerous lives in many countries. Although many such collapses occurred following the ascent of magma to the surface, many are not associated with magmatic reawakening but are triggered by a combination of forcing agents such as pore-fluid pressurization and/or(More)