In the Ore Mountains (Erzgebirge) which form the border between Czechia and Germany, western Bohemia and the Vogtland region have been known since the 16th century as frequently prone to earthquake swarms which typically last a few weeks to a few months. Austrian geologist Josef Knett, while studying in 1899 a swarm of about a hundred events felt in western Bohemia/Vogtland in January-February 1824, coined the noun Schwarmbeben, i.e. swarm [earth]quake. The term swarm is explained by hypocentres giving the impression to agglutinate like a bee swarm when plotted onto a map, a cross-section, or still better onto a 3D model.