# Seismic sources and Earth structure in the transition zone between Fore-Balkan unit and Moesian platform, NE Bulgaria

Seismic sources and Earth structure in the transition zone between Fore-Balkan unit and Moesian... Investigations of hydraulically induced micro-seismicity are typically connected with magma injections, exploitation of geothermal fields and salt mines. Our study examines the seismicity and seismic sources in a peri-platform region with long salt production history. In addition, a very large site for extraction of aggregates and limestone is presented in the area. Increased seismicity in the region has been observed for several decades as during the study period of the last 12 years, more than 1000 events with magnitude M<4.3\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$M < 4.3$$\end{document} have been registered. To study the complex seismic sources concentrated in such small area spatial distribution of seismicity and fault plane solutions are analyzed together with available geological and geophysical data, in order to connect registered earthquakes swarms with geological structures. Results show that several faults are outlined from geological information and confirmed by interpretation of geophysical data. Very different focal mechanisms calculated for the 13 earthquakes in the near region of the salt production site cannot propose a dominant fault mechanism and confirm the complexity of the seismic sources in the area. Our results suppose that activation of some of these structures is more likely due to water injected in the salt dome as part of the production process, which changes the stress equilibrium in the Earth crust. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png "Acta Geodaetica et Geophysica" Springer Journals

# Seismic sources and Earth structure in the transition zone between Fore-Balkan unit and Moesian platform, NE Bulgaria

, Volume 55 (2) – Jun 14, 2020
20 pages

/lp/springer-journals/seismic-sources-and-earth-structure-in-the-transition-zone-between-GKQh00kLl3
Publisher
Springer Journals
ISSN
2213-5812
eISSN
2213-5820
DOI
10.1007/s40328-020-00288-3
Publisher site
See Article on Publisher Site

### Abstract

Investigations of hydraulically induced micro-seismicity are typically connected with magma injections, exploitation of geothermal fields and salt mines. Our study examines the seismicity and seismic sources in a peri-platform region with long salt production history. In addition, a very large site for extraction of aggregates and limestone is presented in the area. Increased seismicity in the region has been observed for several decades as during the study period of the last 12 years, more than 1000 events with magnitude M<4.3\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$M < 4.3$$\end{document} have been registered. To study the complex seismic sources concentrated in such small area spatial distribution of seismicity and fault plane solutions are analyzed together with available geological and geophysical data, in order to connect registered earthquakes swarms with geological structures. Results show that several faults are outlined from geological information and confirmed by interpretation of geophysical data. Very different focal mechanisms calculated for the 13 earthquakes in the near region of the salt production site cannot propose a dominant fault mechanism and confirm the complexity of the seismic sources in the area. Our results suppose that activation of some of these structures is more likely due to water injected in the salt dome as part of the production process, which changes the stress equilibrium in the Earth crust.

### Journal

"Acta Geodaetica et Geophysica"Springer Journals

Published: Jun 14, 2020