Earthquake swarms and accompanying phenomena in intraplate regions: A review

The western part of the Bohemian Massif has played an exceptional role in r ecent geodynamic activity of the region. It is characterised by repeated oc currences of earthquake swarms and by other manifestations of deep tectonic processes (CO2 emissions, anomalous He-3 content, mineral waters, mofettes , etc.). The purpose of this paper is to introduce some other intraplate re gions with earthquake swarm occurrence (French Massif Central; Colli Albani and Vulsini Mts., central Italy; Southern Apennines, Italy; the Danville a nd Long Valley regions, California; central Arkansas), and with artificiall y induced earthquake swarms (Larderello, Italy, geothermal field; Coso, Cal ifornia, geothermal field; NE Bavaria, Germany, deep drilling project). Alt hough these areas represent different tectonic environments, the manifestat ions of recent geodynamic and/or man-made activity are similar in many aspe cts. This coincidence most probably issues front a common cause of both tec tonic and artificially induced earthquake swarms of fluids. Since the regio ns with earthquake swarm occurrence of tectonic origin are situated as a ru le in the close neighbourhood of Quaternary volcanoes, the intruding fluids seem to be derived from magma recently transported to upper crustal layers .