Publication Date:
2017-04-04
Description:
An edited version of this paper was published by AGU. Copyright (2009) American Geophysical Union
Description:
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.
Description:
Published
Description:
B11307
Description:
3.3. Geodinamica e struttura dell'interno della Terra
Description:
JCR Journal
Description:
reserved
Keywords:
joint inversion
;
density
;
04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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