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We present a new hierarchical time kinematic source inversion method able to assimilate data traces through evolutive time windows. A linear time domain formulation relates the slip rate function and seismograms, preserving the positivity of this function and the causality when spanning the model space: taking benefit of the time‐space sparsity of the rupture model evolution is as essential as considering the causality between rupture and each record delayed by the known propagator operator different for each station. This progressive approach, both on the data space and on the model space, does require mild assumptions on prior slip rate functions or preconditioning strategies on the slip rate local gradient estimations. These assumptions are based on simple physical expected rupture models we foresee. Successful applications of this method to a well‐known benchmark (Source Inversion Validation Exercise 1) and to the recorded data of the 2016 Kumamoto mainshock (Mw=7.0) illustrate the advantages of this alternative approach of a linear kinematic source inversion. This stabilized overparameterized optimization of a linear forward problem has a potential extension to stochastic inversion in a Bayesian framework in the future to assess uncertainties on kinematic source inversions, which is more difficult to investigate under nonlinear formulations. In this paper we present a new method to infer the spatial and temporal history of an earthquake through the progressive analysis of seismograms that are not completely recorded at a given moment. Nowadays, the inference of an earthquake history is a common procedure that seismologists do after some minutes of the occurrence of an earthquake. The reconstruction of this history implies explaining many physical unknowns by interpreting the available seismograms. In this work we provide evidences that a progressive reconstruction is possible through the analysis of partially recorded seismograms. Furthermore, we find that the final reconstruction of such history appears to be better through the progressive analysis of seismograms than the results obtained with a traditional analysis of completely recorded seismograms. An alternative linear inverse formulation for kinematic source reconstruction is presentedSuch formulation can invert progressively growing data time windows while spanning the model spacePromising advantages of this method are found, thanks to the preservation of causality and sparsity

We retrieve 3‐D attenuation images of the crustal volume embedding the fault system associated with the destructive Ms6.9, 1980 Irpinia earthquake by tomographic inversion of t*measurements. A high QPanomaly is found to be correlated with the 1980 fault geometry, while the QSmodel shows regional‐scale variations related to the NE edge of the uplifted pre‐Tertiary limestone. An upscaling strategy is used to infer rock properties such as porosity, consolidation, type of fluid mixing, and relative saturation percentage at 8–10 km fault depth. We constrain the porosity and consolidation in the ranges 4–5% and 5–9, respectively, with the possible fluid mixes being both brine‐CO2and CH4‐CO2. The consolidation parameter range indicates high pore pressures at the same depths. These results support the evidence for a fracture system, highly saturated in gases and a seismicity triggering mechanism at the fault zone, which is strongly controlled by fluid‐induced pore pressure changes. Three‐dimensional attenuation images and rock properties of the crustal volume embedding the fault system associated with the destructive Ms6.9, 1980 Irpinia earthquakeEvidence for a fractured and fluid‐saturated medium, with the presence of brine‐CO2and CH4‐CO2Pore pressure increase is the dominant mechanisms triggering and controlling the microseismicity

We present the spatio-temporal distribution of more than 2000 earthquakesthat occurred during the Umbria-Marche seismic crisis, between September 26and November 3, 1997. This distribution was obtained from recordings of atemporary network that was installed after the occurrence of the first two largest shocks (Mw =, 5.7, Mw = 6.0) of September 26. This network wascomposed of 27 digital 3-components stations densely distributed in theepicentral area. The aftershock distribution covers a region of about 40 km long and about2 km wide along the NW-SE central Apennines chain. The activity is shallow,mostly located at less than 9 km depth. We distinguished three main zonesof different seismic activity from NW to SE. The central zone, that containsthe hypocenter of four earthquakes of magnitude larger than 5, was the moreactive and the more complex one. Sections at depth identify 40–50°dipping structures that agree well with the moment tensor focalmechanisms results. The clustering and the migration of seismicity from NW to SE and the generalfeatures are imaged by aftershock distribution both horizontally and at depth.

Since 1994, important modifications have been implemented in the dental curriculum in France, and an additional year has been included in the dental curriculum. The 1st year has remained unchanged; it is common to both medical and dental schools and leads to a selection procedure of 1 in 10 dental students. In the new curriculum, the dental student is engaged in a 5‐year programme in dental school (years 2 to 6), as opposed to 4 years in the former programme (years 2 to 5). Basically, this new curriculum emphasises research initiation, links with medical training and offers broader clinical experience. During the academic year 1998–1999, dental schools had 2 different types of students: the 4th year students belonging to the new programme along with the 5th year students in their final year of the old curriculum. Using a specially devised questionnaire, we investigated the students’ perception of their respective training, their motivation and professional plans. At the Faculty of Odontology in Lyon, the new curriculum is perceived as an increased strain by the dental students.

We compute the thermal evolution of a lithosphere submitted to stretching during a finite duration of time in order to discuss the initial stretching phase of future continental margins. The numerical method developed can handle 2-D laterally variable stretching as well as sedimentation. It is shown that lateral conduction is more important than vertical conduction over most continental margins during their formation by stretching. A simple way to evaluate the relative importance of lateral and vertical conduction effects at the axis of the zone of rifting just prior to oceanization is proposed. A simple way to evaluate the amplitude of the thermal uplift on the edges of the zone of rifting at the end of the stretching phase is also presented. For small width zones of rifting (< 70–100 km) lateral cooling becomes so large as to prevent large-scale melting and, presumably, prevent the transition to oceanization. The effect of high-sedimentation rates (100–500 m Myr−1) is to increase the surface temperature of the lithosphere and consequently significantly decrease the surface heat flow.

A preliminary study of the aftershocks of three earthquakes that occurred near to Corinth (Greece) in 1981 is combined with observations of the morphology and faulting to understand the evolution of the Eastern Gulf of Corinth. The well located aftershocks form a zone 60km long and 20km wide. They do not lie on the main fault planes and are mostly located between the north-dipping faulting on which the first two earthquakes occurred and the south-dipping faulting associated with the third event. A cluster of aftershocks also lies in the footwall of the eastern end of the south-dipping fault of the third event. Morphologically, it is observed that in the evolution of the Eastern Gulf of Corinth, antithetic faulting apparently predates the appearance of the main faulting at the surface. This evolution can be explained by motion on a deep seated, shallow angle, aseismic normal fault. A model based on such a fault also accounts for the aftershock distribution of the 1981 earthquakes.

We propose a two-step inversion of three-component seismograms that (1) recovers the far-field source time function at each station and (2) estimates the distribution of co-seismic slip on the fault plane for small earthquakes (magnitude 3 to 4). The empirical Green's function (EGF) method consists of finding a small earthquake located near the one we wish to study and then performing a deconvolution to remove the path, site, and instrumental effects from the main-event signal. The deconvolution between the two earthquakes is an unstable procedure: we have therefore developed a simulated annealing technique to recover a stable and positive source time function (STF) in the time domain at each station with an estimation of uncertainties. Given a good azimuthal coverage, we can obtain information on the directivity effect as well as on the rupture process. We propose an inversion method by simulated annealing using the STF to recover the distribution of slip on the fault plane with a constant rupture-velocity model. This method permits estimation of physical quantities on the fault plane, as well as possible identification of the real fault plane. We apply this two-step procedure for an event of magnitude 3 recorded in the Gulf of Corinth in August 1991. A nearby event of magnitude 2 provides us with empirical Green's functions for each station. We estimate an active fault area of 0.02 to 0.15 km2 and deduce a stress-drop value of 1 to 30 bar and an average slip of 0.1 to 1.6 cm. The selected fault of the main event is in good agreement with the existence of a detachment surface inferred from the tectonics of this half-graben.

In previous studies, anomalies in arrival time and amplitudes of depth phases pP and sP recorded at teleseismic distances and produced by large intermediate-depth events of the Vrancea region were pointed out (Perrot et al. 1994). the modelling of major recent events has shown that the presence of a dipping interface and thick low-velocity sediment layer in the upper crust above the hypocentral area can explain such anomalies. Simulating broad-band records of the 1990 May 31 earthquake, it is shown that the 2-D crustal velocity model derived by Perrot et al. (1994) can also be used to explain observed waveforms in an extended azimuthal range from 105° to 243° and is valid for earthquakes having different hypocentral locations in the deep Vrancea seismic zone. Using records in the azimuthal range where a classical spherical model produces a good fit to the observed waveforms, the source is best modelled by two point sources at 90 and 93 km depth releasing the same amount of seismic moment, and separated by 1.5 s in time. Synthetics calculated for this source time history and the 2-D velocity model above the source give a much improved fit of the observed waveforms over what could be achieved with a 1-D spherical model. the results suggest that teleseismic waveforms could be reasonably well predicted for any event in the region with the 2-D velocity model, which accounts for the main structural features in the upper crust of the Vrancea region.