Vibration effect of earthquakes in abandoned medieval mine

Abstract

The information on seismic loading and vibration effect is significant when assessing stability of underground spaces located in the vicinity of seismic active areas. Underground structures are well known to be earthquake resistant. Nevertheless, the existence of discontinuities makes them vulnerable to collapses, particularly in case of shallow underground openings. This study presents results of long-term seismic monitoring performed in the shallow medieval mine. This mine is located at a distance of about 25 km southeast of Nový Kostel focal zone (West Bohemia, Czech Republic), where seismic activity in the form of seismic swarms occurs. The most intensive earthquakes were documented here in the past with local magnitude M L =5.0. During two intensive seismic swarms from the Nový Kostel focal zone in 2008 (M L ≤3.8) and 2011 (M L ≤3.7), almost 2000 earthquakes were recorded at the seismic station in the mine. Vibration effect underground was analysed together with results of geomechanical monitoring. Based on the measured data, vibration effect in the mine was extrapolated for an expected more intensive earthquake with the local magnitude M L =5.0.