Understanding the causal mechanisms of large devastating earthquakes in intraplate areas is a long-term challenge. Current seismic swarms and CO2 outflows in western Bohemia are often attributed to magmatic processes. Paleoseismic research at the Marianske Lazne fault, which crosses the focal zone, revealed the occurrence of two major earthquakes in the last 3 thousand. years, which broke the surface, the youngest of them around 1000 AD.