Options
Achauer, U.
Loading...
2 results
Now showing 1 - 2 of 2
- PublicationRestrictedUnveiling seismic and density structure beneath the Vrancea seismogenic zone, Romania(2009-11-12)
; ; ; ; ; ;Tondi, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Achauer, U.; EOST, Strasbourg - France ;Landes, M.; Indiana University, Indiana - USA ;Davi', R.; University College Dublin, Dublin - IRELAND ;Besutiu, L.; Romanian Academy, Bucharest - Romania; ; ; ; The Vrancea seismogenic zone in Romania exhibits an intense intermediate-depth seismicity, confined to a relatively small, roughly cylindrical and elongated region, whose origin is still under debate. Our three-dimensional P and S wave velocity and density images put additional physical constraints on the existing tectonic models to a depth of 200 km. The results appear to substantiate a combination of lithospheric delamination and oceanic subduction. For our analysis, we apply the tomographic inversion method of sequential integrated inversion (SII) to P and S first arrivals from active source data collected during the VRANCEA99 and VRANCEA2001 seismic refraction experiments, local earthquake data collected during the Carpathian Arc Lithosphere X-Tomography (CALIXTO) experiment and recent gravity measurements of the studied area. The reconstructed models, which explain both travel times and gravity data, show a subducting slab which exhibits fast Vp, fast Vs, high density, and a low Vp/Vs ratio consistent with the cold downgoing plate. We associate intermediate-depth seismicity with the observed sharp lateral Vp/Vs variations presumably generated by contact between the dense and cold slab and the lithospheric mantle in the shallower part or the asthenosphere in the deeper part. This contrast is particularly evident between 100 and 150 km depth, where the maximum historical seismic energy release is concentrated. Our results indicate the diagnostic power of a combined interpretation of 3-D Vp, Vs, Vp/Vs, and density models.502 35 - PublicationOpen AccessLooking inside mt. vesuvius(1998)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Italy's Mt.Vesuvius has been slumbering for a long time, but its silence could preface an eruption with potentially disastrous effects for 600,000 people living on the volcano's slopes. To assess the scenario of the next eruption, the National Group of Vol-canology (GNV) of the Italian National Council of Researches (CNR) has fostered research aimed at mitigating eruption risk to the densely populated area. In this framework, researchers have gathered high-resolution seismic tomography data to better understand the internal structure of Mt. Vesuvius. The experiments were carried out during the last 4 years. The data will be used in three-dimensional modeling of the structure of Mt. Vesuvius and underlying upper crust. Seismic velocities and attenuation and density contrasts will be calculated, with special emphasis on the delineation of significant magma reservoirs of more than 1 km in diameter. In modeling Mt. Vesuvius, tools are being developed for using seismogram information to obtain high-quality seismic imaging of heterogeneous structures such as volcanoes221 33