Increased seismicity at the beginning of the twentieth century in the intraplate region of Czechia and neighboring areas in Central Europe

Abstract

The broader region of the Czech Republic in Central Europe experiences moderate seismicity. However, determination of seismic hazard is significant due to its dense population, large cities, and developed industrial infrastructure, including nuclear power plants. A new catalogue of historical earthquakes has been compiled for the Czech Republic and its surrounding areas, covering the period up to the end of 2023. The catalogue was analysed in terms of seismicity variations over the last 164 years (1860–2023). It was shown, that there was a significant increase in seismicity from 1896 to 1910 compared to the present state, in most of the source zones, which are important for the seismic hazard of the region. Significant earthquakes from this period are well documented in historical records, and some also by old seismograms, making it certain that similar strong earthquakes did not occur in later years until now. A strong correlation has been shown with earthquakes in Italy, a highly seismically active area on the margin of the Eurasian tectonic plate, which is more than 200 km away from the study region. However, the physical cause of this variation in seismicity in both regions is unclear. The demonstrated variation in seismicity has essential implications for the methodology of seismic hazard evaluation.