Technical Committee Geophysics
High Resolution Seismic Survey of the Seismicity near Rothenburg and Comparison of Survey Methods
In the context of the DGMK project 761, the Rotenburg region has been monitored by a local high-resolution seismic network for the last two years. The surface network currently consists of three arrays and five single seismic stations. Additionally, WEG and BGR data from surface and underground seismic stations has been used.
Development and adaptation of automatic detection methods to the specific network configuration has significantly improved monitoring and detection of seismic events within and beyond the region of focus, and a detection threshold of magnitude 0.2 ML has been achieved. Surprisingly, no small events in close ambit of the network have been observed as it had been expected from the major local earthquakes 2004 ML 4.5 Rotenburg and 2012 ML 2.9 Visselhövede. Sensitivity of the network has been estimated from multiple shallow, probably induced events at Walsrode and Völkersen clusters. Additionally, the removal of fixed depth assumption has revealed four singular, deeper earthquakes (25-30 km). These observations confirm that the seismo-tectonic situation in Northern Germany is very complex and anthropogenic processes cannot be assumed as the only source of regional seismicity.