 | |
  | |
| UTC time | 1930-07-23 00:08:41 |
|---|---|
| ISC event | 907513 |
| USGS-ANSS | ComCat |
| Local date | 23 July 1930 (1930-07-23) |
| Local time | 01:08:41 |
| Magnitude | 6.6Ms[1] |
| Epicenter | 41°03′00″N15°22′01″E / 41.05°N 15.367°E /41.05; 15.367 |
| Areas affected | Italy,Basilicata andApulia |
| Max. intensity | EMS-98 X (Very destructive) |
| Casualties | 1,404 dead[2] 4,624–7,000 injured[2] 100,000 displaced[2] |
The1930 Irpinia earthquake occurred at 00:08UTC on 23 July, chiefly in an area known asIrpinia. It had asurface-wave magnitude of 6.6 and a maximum intensity ofX (Very destructive). The event caused 1,404 deaths and 4,624–7,000 injuries. Theepicenter was near the boundaries between the regions ofBasilicata,Apulia, andCampania.
The central and southern part of theApennines has been characterised byextensional tectonics since thePlioceneepoch (i.e. about the last five million years), with most of theactive faults being normal in type and NW-SE trending.[3] The extension is due to theback-arc basin in theTyrrhenian Sea opening faster than theAfrican plate iscolliding with theEurasian plate.[4] 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 covered about 6,300 km2 (2,400 sq mi), lying between theGarigliano River, theCrati valley, and theBiferno andMurgia areas, including parts of highIrpinia, theVulture area, theSannio Hills,Salerno,Naples, theprovince of Matera and the highest parts ofApulia. In the worst damaged areas, about seven out of ten houses were almost completely destroyed, an outcome made worse by the poor strength of many buildings.[2] The death toll was reported as 1,404, with some three quarters of the victims being in theprovince of Avellino. The death toll was low, considering the level of physical damage, a fact partly explained by the number of villagers who were away from their houses, many sleeping in the fields while working on the wheat harvest.[2]
The main shock was preceded by two foreshocks a few hours earlier and followed by 16 aftershocks within the first 24 hours.[2] The greatestintensity of X (Very destructive) on theEuropean Macroseismic Scale was recorded atAquilonia Vecchia,Lacedonia andVillanova del Battista. Intensities of IX (Destructive) were recorded atAnzano degli Irpini,Scampitella,Castel Baronia,Melfi,Montecalvo Irpino,Rocchetta Sant'Antonio andTrevico. 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.[1]
