1930 Irpinia earthquake
|Date||3 July 1930|
|Countries or regions||Italy, Basilicata|
The 1930 Irpinia earthquake occurred at 00:08 UTC on 23 July 1930. It had a magnitude of 6.6 and caused 1,404 deaths. The epicenter was close to the borders between the regions of Basilicata, Puglia and Campania.
The central and southern part of the Apennines has been characterised by extensional tectonics since the Pliocene epoch (i.e. about the last 5 million years), with most of the active faults being normal in type and NW-SE trending. The extension is due to the back-arc basin in the Tyrrhenian Sea opening faster than the African Plate is colliding with the Eurasian Plate. To the northeast of the Apennine chain, the foreland is in contrast affected by W-E trending strike-slip to oblique-slip faults.
The area affected was about 6,300 km2, between the Garigliano River, the Crathis valley, and the Biferno and Murgia areas, including parts of high Irpinia, the Vulture, Sannio, Salerno, Naples, the province of Matera and high Puglia. In the most damaged areas, about 70% of the houses were completely destroyed, made worse by the poor quality of the buildings. The death toll was 1,404, with 75% of the victims being in the province of Avellino. The death toll was low considering the level of damage, a fact explained by the number of villagers who were sleeping in the fields during the wheat harvest.
The main shock was preceded by two foreshocks a few hours earlier and followed by 16 aftershocks within the first 24 hours. The greatest intensity of X (very destructive) on the European Macroseismic Scale was recorded at Aquilonia Vecchia, Lacedonia and Villanova del Battista. Intensities of IX (destructive) were recorded at Anzano degli Irpini, Scampitella, Castel Baronia, Melfi, Montecalvo Sant'Antonio and Trevico. The area of maximum intensity is elongated in a roughly W-E direction. Analysis of historical seismograph recordings suggest that the earthquake originated from a north-dipping fault plane striking N100°E.
- Guidoboni, E.; Ferrari G., Mariotti D., Comastri A., Tarabusi G., & Valensise G. "Catalogue of Strong Earthquakes in Italy 461 B.C.- 1997 and Mediterranean area 760 B.C. - 1500" (in italian). Retrieved 6 July 2010.
- "Effect of Time Dependence on Probabilistic Seismic-Hazard Maps and Deaggregation for the Central Apennines, Italy". Seismological Society of America. 6 April 2009. Archived from the original on 29 July 2009. Retrieved 6 April 2009.
- "Magnitude 6.3 - CENTRAL ITALY 6 April 2009 01:32:42 UTC". USGS. 6 April 2009. Archived from the original on 9 April 2009. Retrieved 6 April 2009.
- Pino, N.A.; Palombo B., Ventura G., Perniola B. & Ferrari G. (2008). "Waveform modeling of historical seismograms of the 1930 Irpinia earthquake provides insight on "blind" faulting in Southern Apennines (Italy)". Journal of Geophysical Research 113 (B05303). Bibcode:2008JGRB..11305303P. doi:10.1029/2007JB005211. Retrieved 6 July 2010.