DOI: 10.5593/SGEM2016/B13/S05.079


B.Zaharia, B. Grecu, D. Tataru, E. Oros
Tuesday 6 September 2016 by Libadmin2016

References: 16th International Multidisciplinary Scientific GeoConference SGEM 2016, www.sgem.org, SGEM2016 Conference Proceedings, ISBN 978-619-7105-57-5 / ISSN 1314-2704, June 28 - July 6, 2016, Book1 Vol. 3, 623-630 pp

We propose to investigate the local seismic events in the western part of Romania using data from the SCP experiment, a joint project between University of Leeds, UK and National Institute for Earth Physics, Romania (South Carpathian Project – SCP), using 33 broadband seismic stations autonomously that operated in the western part of the country and continuously recorded data for two years (2009-2011). The seismicity in this area is characterized by shallow activity of moderate magnitude (magnitude below 6) earthquakes with frequent multiple sequences. Tectonically, the region is divided into blocks and basins bordered by intra-crustal faults. The major structural features developed in the region are: the Pannonian Basin with a thin subsiding lithosphere (cca 60 km) and four Dacidic units (Inner Dacides (ID), Transilvanides (T), Middle Dacides (MD), Marginal Dacides (MaD) and Outer Dacides (OD)) with a thicker lithosphere (100 - 140 km), uplifted by recent orogeny. These structures outcrop in the mountain chains and extend westward under the sedimentary cover of the Pannonian Depression. The newest (Neotectonic) tectogeneses were extensional (syn-rift phase) and compressional (basin inversion) resulting in brittle structures: grabens and horsts, separated by NW-SE oriented faults, affecting both the basement and the sedimentary cover. Two Neogene NW-SE oriented major grabens developed at the basement level of the Pannonian Basin: Sannicolau Mare in the West and Caransebes in the East. These structures are extended in the mountains as small depressions, controlled by Neogene normal faults, with the basement lowered down to over 7 km (at Hungary - Romania border). We applied the Wadati method to estimate the Vp/Vs ratio and used it to retrieve a P-wave velocity model for the investigated region. For a better constraint of local seismic events locations, we used the derived P-wave velocity model to relocate all the events using Joint Hypocentral Determination (JHD) method.

Keywords: local seismic events, JHD method, velocity models