Search

Your search keyword '"Qorbani, Ehsan"' showing total 19 results
Start Over Author "Qorbani, Ehsan"
19 results on '"Qorbani, Ehsan"'

5. Crustal structures beneath the Eastern and Southern Alps from ambient noise tomography

Author

Qorbani, Ehsan, Zigone, Dimitri, Handy, Mark R., Bokelmann, Götz, and AlpArray-EASI working group

Subjects
lcsh:Geology, Geophysics, lcsh:Stratigraphy, Geochemistry and Petrology, Stratigraphy, lcsh:QE1-996.5, Paleontology, Soil Science, Geology, Earth-Surface Processes, Physics::Geophysics, lcsh:QE640-699
Abstract

We study the crustal structure under the Eastern and Southern Alps using ambient noise tomography. We use cross-correlations of ambient seismic noise between pairs of 71 permanent stations and 19 stations of the Eastern Alpine Seismic Investigation (EASI) profile to derive new 3D shear velocity models for the crust. Continuous records from 2014 and 2015 are cross-correlated to estimate Green's functions of Rayleigh and Love waves propagating between the station pairs. Group velocities extracted from the cross-correlations are inverted to obtain isotropic 3D Rayleigh- and Love-wave shear-wave velocity models. Our models image several velocity anomalies and contrasts and reveal details of the crustal structure. Velocity variations at short periods correlate very closely with the lithologies of tectonic units at the surface and projected to depth. Low-velocity zones, associated with the Po and Molasse sedimentary basins, are imaged well to the south and north of the Alps, respectively. We find large high-velocity zones associated with the crystalline basement that forms the core of the Tauern Window. Small-scale velocity anomalies are also aligned with geological units of the Austroalpine nappes. Clear velocity contrasts in the Tauern Window along vertical cross sections of the velocity model show the depth extent of the tectonic units and their bounding faults. A mid-crustal velocity contrast is interpreted as a manifestation of intracrustal decoupling in the Eastern Alps that accommodated eastward escape of the Alcapa block.

Published
2020

17. Upper crustal structure at the KTB drilling site from ambient noise tomography.

Author

Qorbani, Ehsan, Bianchi, Irene, Zigone, Dimitri, Kolínský, Petr, and Bokelmann, Götz

Subjects
*TOMOGRAPHY, *CROSS correlation, *GROUP velocity, *NOISE, *SEISMIC anisotropy, *VELOCITY, *SURFACE waves (Seismic waves)
Abstract

In this study, we show results from ambient noise tomography at the KTB drilling site, Germany. The Continental Deep Drilling Project, or 'Kontinentales Tiefbohrprogramm der Bundesrepublik Deutschland' (KTB) is at the northwestern edge of the Bohemian Massif and is located on the Variscan belt of Europe. During the KTB project crustal rocks have been drilled down to 9 km depth and several active seismic studies have been performed in the surrounding. Therefore the KTB area is here taken as a sample for testing and verifying the potential resolution of passive seismic techniques. The aim of this study is to present a new shear-wave velocity model of the area while comparing the results to the previous velocity models and hints for anisotropy depicted by former passive and active seismological studies. We use a unique data-set composed of two years of continuous data recorded at nine 3-component temporary stations installed from July 2012 to July 2014 located on top and vicinity of the drilling site. Moreover, we included a number of permanent stations in the region in order to improve the path coverage and density. Cross correlations of ambient noise are computed between the station pairs using all possible combination of three-component data. Dispersion curves of surface waves are extracted in the 0.07 to 3 Hz frequency band and are then inverted to obtain group velocity maps. We present here a new velocity model of the upper crust, which shows that velocity variations at short periods (down to 12 km depth) correlate well with geology of the region. [ABSTRACT FROM AUTHOR]

Published
2019

Catalog

Books, media, physical & digital resources
See catalog results