Seismology

With regard to the number and intensity of earthquakes, the territory of Slovenia is quite an active area. This is because the country lies on the seismically active southern boundary of the Eurasian tectonic plate on the north-western boundary of the Mediterranean-Himalayan seismic belt, which is one of the most seismically active zones on Earth. The small Slovenian territory is the juncture of three geotectonic units: the Alps in the north and west, the Dinarides in the southern, south-western and central part, and the Pannonian Basin in the northeast. The reason for numerous weak and strong earthquakes lies in the complex geological and tectonic structure of this territory, which lies on the small Adriatic plate squeezed between the African plate to the south and the Eurasian plate to the north. The Adriatic plate rotates counter-clockwise, which causes different movements, particularly on the northern and eastern side. The southern and western parts of Slovenia lie on the northern part of the Adriatic plate, which is strongly deformed and overlaps the less-deformed central part of the plate. Movement of these parts in different directions builds up tension that can cause earthquakes. On Slovenian territory, movements of plates create tension in the direction N–S, which is released in the form of earthquakes on tectonic fault lines in the direction NW–SE (Dinaric direction) and NE–SW (cross-Dinaric direction), and on overlapping structures running in the direction E–W.

By examining historical sources and by recording and monitoring seismic phenomena in the recent period, we can see that more than 60 devastating earthquakes have occurred on Slovenian territory in the past. In addition to causing material damage, earthquakes have also claimed many human lives. Apart from the Ljubljana area, where the most seismic energy was released in the past, the most earthquake-prone areas in Slovenia are the Idrija area, the Tolmin area and the Krško–Brežice area. Earthquake foci are formed throughout the entire territory of Slovenia, the fewest being in the extreme north-eastern part of the territory. In the 20_th century alone there were more than 20 earthquakes in Slovenia, with some of them having an intensity of 7 EMS or more, which caused minor or major damage to property.

The Environmental Agency of the Republic of Slovenia performs the following activities in the field of seismology:

• continuous monitoring and evaluation of seismic activity on the territory of Slovenia and other areas
• providing information on major earthquakes
• establishing a network of seismic stations in Slovenia
• placing temporary seismic stations during periods of increased seismic activity
• carrying out macro seismic investigations and drawing up earthquake catalogues
• coordinating geological and geophysical investigations related to seismic activity
• drawing up maps of seismic risk and hazard
• elaborating assessments of seismic activity in individual areas
• performing tasks in the field of earthquake engineering and engineering seismology
• exchanging data with international seismological centres