The 1511 Idrija earthquake (Slovene: idrijski potres or potres na Idrijskem) occurred on 26 March 1511 with a moment magnitude of 6.9 and a maximum EMS intensity of X (very destructive).[3] The epicenter was near the town of Idrija (now in Slovenia), although some place it in Friuli.[1] The earthquake affected a large territory between Carinthia, Friuli, present-day Slovenia and Croatia. An estimated 3,000 people were killed and damage was considered severe. The earthquake was felt as far as in Switzerland and present-day Slovakia. A number of castles and churches were razed to the ground in a large area from northeast Italy to western Croatia.[1] Among the destroyed buildings were the castles of Udine and Škofja Loka, the monastery of the Teutonic Knights in Ljubljana; the Zagreb cathedral was severely damaged. Blaž Raškaj, commander of the Jajce fortess (now in Bosnia), reported to the Hungarian Estates that the earthquake had severely damaged the fortifications.
  Ljubljana  | |
| Local date | March 26, 1511 |
|---|---|
| Local time | 15:30 CET[1] |
| Magnitude | 6.9 Mw |
| Epicenter | 46°12′N 13°26′E / 46.2°N 13.43°E [2] |
| Total damage | Severe [2] |
| Max. intensity | EMS-98 X (Very destructive)[2] |
| Tsunami | Yes [2] |
| Casualties | 3,000 dead[3] |
The reconstruction of the destroyed buildings in the following decades is considered the dividing line between Gothic and Renaissance architecture in the art history of the Eastern Alps.[citation needed]
Tectonic setting edit
The area affected by the earthquake lies within the Julian Alps, close to the border between Italy and Slovenia. The ongoing convergence between the African Plate and Eurasian Plate leads to active faulting in this part of the Alps. The type of faulting varies from thrust faulting in the west of the area, in the Southern Alps to dextral (right lateral) strike-slip faulting to the east, in the Dinaric Alps.[4][5]
Earthquake edit
Several large earthquakes have been described as occurring before, during or after the 1511 event. Reanalysis of contemporary records has, however, reduced the number of events. A possible foreshock in 1510 has been attributed to errors introduced in sources written well after the event. Two main shocks on the same day, relying on separate Italian and Slovenian sources have been reconciled as local time in Italy in the 16th Century was counted from sunset, not midnight and a single event is now accepted.[5] Modelling of possible earthquake sources compared to the distribution of damage also supports a single event.[4] Another earthquake said to have affected the area on August 8, 1511 has also been discounted due to a lack of any evidence in contemporary sources.[5]
The Idrija earthquake occurred at about 15:00–15:30 local time on March 26, 1511. The magnitude of the event has been estimated from the distribution of seismic intensities to be about 6.9 Mw .[4][6] A lower magnitude of Mw 6.3 has been estimated, based on a revision of the intensities, particularly in Slovenia.[5][7]
The causative fault remains uncertain, although modelling of expected seismic intensities from different potential fault sources has shown that strike-slip faulting along a NW–SE trending fault gives the best match to the observations.[4] Trenching across two of the larger dextral strike-slip faults, the Idrija Fault and the Predjama Fault have found evidence for past earthquakes but in neither case are the dates consistent with the timing of the 1511 event.[8] Trenching has also been carried out on the ~25 km long Borgo Faris–Cividale Fault and the associated Colle Villano Thrust. These investigations found evidence for two events, the most recent of which occurred in the 15th to 17th Century period, consistent with the 1511 event. The length of the fault zone is also consistent with the proposed lower magnitude estimate of 6.3.[7]
Aftershocks edit
Eyewitness accounts mention a prolonged series of aftershocks lasting for several weeks and up to a year after the mainshock. Further earthquakes were noted on March 28, April 19, May 15, June 5, June 6, June 24, June 25 and October 3.[9]
See also edit
References edit
- ^ a b c Cecič, Ina (2011). "Idrijski potres 26. marca 2011" [The 26 March 1511 Earthquake – What Do We Know About It?] (PDF). Geografski obzornik [Geographic Horizon] (in Slovenian). 58 (1). Association of Slovenian Geographers. ISSN 0016-7274.
- ^ a b c d National Geophysical Data Center / World Data Service (NGDC/WDS) (1972), Significant Earthquake Information, National Geophysical Data Center, NOAA, doi:10.7289/V5TD9V7K
- ^ a b "Potresi in nova karta potresne nevarnosti Slovenije" [Earthquakes and a new Earthquake Hazard Map of Slovenia] (in Slovenian). Geological Survey of Slovenia. Retrieved 23 April 2024.
- ^ a b c d Fitzko, F.; Suhadolc, P.; Aoudia, A.; Panza, G.F. (2005). "Constraints on the location and mechanism of the 1511 Western-Slovenia earthquake from active tectonics and modeling of macroseismic data". Tectonophysics. 404 (1–2): 77–90. Bibcode:2005Tectp.404...77F. doi:10.1016/j.tecto.2005.05.003.
- ^ a b c d Camassi, R.; Caracciolo, C.H.; Castelli, V.; Slejko, D. (2011). "The 1511 Eastern Alps earthquakes: a critical update and comparison of existing macroseismic datasets" (PDF). Journal of Seismology. 15 (2): 191–213. Bibcode:2011JSeis..15..191C. doi:10.1007/s10950-010-9220-9.
- ^ SHARE. "1511 03 26 14:40 - Slovenia". SHARE European Earthquake Catalogue (SHEEC) 1000-1899. Retrieved April 25, 2024.
- ^ a b Falcucci, E.; Poli, M.E.; Galadini, F.; Scardia, G.; Paiero, G.; Zanferrari, A. (2018). "First evidence of active transpressive surface faulting at the front of the eastern Southern Alps, northeastern Italy: insight on the 1511 earthquake seismotectonics". Solid Earth. 9 (4): 911–922. Bibcode:2018SolE....9..911F. doi:10.5194/se-9-911-2018.
- ^ Grützner, C.; Aschenbrenner, S.; Jamšek Rupnik, P.; Reicherter, K.; Saifelislam, N.; Vičič, B.; Vrabec, M.; Welte, J.; Ustaszewski, K. (2021). "Holocene surface-rupturing earthquakes on the Dinaric Fault System, western Slovenia". Solid Earth. 12 (10): 2211–2234. Bibcode:2021SolE...12.2211G. doi:10.5194/se-12-2211-2021.
- ^ Cecić, I.; Košir, M.; Živčić, M. (2012). "Potres 26. marca 1511 in njegove posledice na naših tleh" (in Slovenian).
Sources
- Ribarič, V. (1979). "The Idrija earthquake of March 26, 1511 —a reconstruction of some seismological parameters". Tectonophysics. 53 (3–4). Elsevier: 315–324. Bibcode:1979Tectp..53..315R. doi:10.1016/0040-1951(79)90076-3.
External links edit
- Page on the 1511 Idrija earthquake from the CFTI5 Catalogue of Strong Earthquakes in Italy (461 BC – 1997) and Mediterranean Area (760 B.C. – 1500) Guidoboni E., Ferrari G., Mariotti D., Comastri A., Tarabusi G., Sgattoni G., Valensise G. (2018) (in Italian)
Media related to 1511 Idrija earthquake at Wikimedia Commons- Tenze, Goran (8 November 2021) Idrijski potres – 510 let od po virih najmočnejšega potresa pri nas [The Idrija earthquake – 510 years since, according to sources, the strongest earthquake in our country] (in Slovenian). Conversation with the researcher Matevž Košir. ARS, RTV Slovenia.
