DBPapers
DOI: 10.5593/sgem2017/14/S05.053

STRESS FIELD, SEISMICITY AND SEISMOTECTONIC FEATURES IN THE APUSENI MOUNTAINS AREA

E. Oros, E.G. Constantinescu, M. Diaconescu, M. Popa
Monday 11 September 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7408-00-3 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 14, 421-428 pp, DOI: 10.5593/sgem2017/14/S05.053

ABSTRACT

The active stress pattern in the Apuseni Mts area is investigated and studied in relation to the local seismicity and geology. Our analysis is based on several high quality and resolution data bases obtained recently in the context of national and international projects and which refers to digital seismograms recorded by dense networks, parametric earthquakes catalogues and catalogues of focal mechanisms. The reduced stress tensor has been obtained by formal inversion of 89 focal mechanisms solutions. The maximum horizontal stress SHmax directions and tectonic regime change at local scale displaying a very heterogeneous stress field and claiming a major influence of local sources of stress. SHmax has systematic reorientations from NE-SW on the western border of the region to E-W in the South, NW-SE in the North and roughly N-S at the tectonic contact between orogenic structures with Transylvanian Depression. The stress and tectonic regimes show clear variations from a pure strike-slip in the structures of Pannonian Depression to extensions all over in the Apuseni Mountains, except the South Transylvanian Fault System area where an extensional strike-slip regime has been computed. The study area is characterized by a very low level of seismicity with a few scattered epicenters in the region or distributed in small clusters mainly on the borders where large neotectonic structures develop (grabens, faults). The study was completed with geodetic data and a seismotectonic model that brings new informations for understanding the seismic hazard and geodynamical processes in the study region.

Keywords: stress field, seismicity, seismotectonic, Apuseni Mountains, focal mechanism