The Idrija Fault (; ) is a seismically

active fault An active fault is a fault that is likely to become the source of another earthquake sometime in the future. Geologists commonly consider faults to be active if there has been movement observed or evidence of seismic activity during the last 10,0 ...

Slovenia Slovenia, officially the Republic of Slovenia, is a country in Central Europe. It borders Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the south and southeast, and a short (46.6 km) coastline within the Adriati ...

. It strikes NW–SE and the fault plane dips towards the northeast. The activity along the fault started in the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

with normal faulting and changed to dextral strike-slip in the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Marko Vincenc Lipold Marko Vincenc Lipold Germanized as Markus Vinzenz Lipold (19 January 1816 – 22 April 1883) was a Slovenian geologist, mountaineer, and mining engineer. Lipold was born in Mozirje, son of a merchant. He studied at Celje and he paid for his ow ...

. The present displacement is measured and varies along strike but is in the order of magnitude of 0.1 mm per year. The strongest earthquake that possibly happened along the Idrija Fault was the

1511 Idrija earthquake The 1511 Idrija earthquake ( or ) occurred on 26 March 1511 with a moment magnitude of 6.9 and a maximum EMS intensity of X (''very destructive''). The epicenter was near the town of Idrija (now in Slovenia), although some place it in ...

, which took place on 26 March 1511. It had a

moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mwg, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. was defined in a 1979 paper ...

of 6.9 and achieved a maximum intensity of X ("very destructive") as per the EMS scale. It caused 3,000 deaths and extensive material damage. In the 20th century, the fault caused the Cerknica Earthquake in 1926 and the in 1998 (both EMS VII–VIII).

References

{{Reflist Geology of Slovenia Dinaric Alps Seismic faults of Europe