The 1930 Irpinia earthquake occurred at 00:08 UTC on 23 July, chiefly in an area known as

Irpinia Irpinia (Modern Latin ''Hirpinia'') is a geographical and cultural region of Southern Italy. It was the inland territory of the ancient ''Hirpini'' tribe, and its extent matches approximately today's province of Avellino. Geography The territor ...

. It had a

surface wave magnitude The surface wave magnitude (M_s) scale is one of the magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements of Rayleigh surface waves that travel along the uppermost layers of the Earth. This ma ...

of 6.6 and a maximum intensity of X (''Very destructive''). The event caused 1,404 deaths and 4,624–7,000 injuries. The

epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage Before the instrumental pe ...

was near the boundaries between the regions of

Basilicata it, Lucano (man) it, Lucana (woman) , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = , demographics1_footnotes = , demographics1_title1 = , demographics1_info1 = ...

Apulia it, Pugliese , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = , demographics1_footnotes = , demographics1_title1 = , demographics1_info1 = , demographic ...

, and

Campania Campania (, also , , , ) is an administrative Regions of Italy, region of Italy; most of it is in the south-western portion of the Italian peninsula (with the Tyrrhenian Sea to its west), but it also includes the small Phlegraean Islands and the i ...

Tectonic setting

The central and southern part of the

Apennines The Apennines or Apennine Mountains (; grc-gre, links=no, Ἀπέννινα ὄρη or Ἀπέννινον ὄρος; la, Appenninus or – a singular with plural meaning;''Apenninus'' (Greek or ) has the form of an adjective, which wou ...

has been characterised by

extensional tectonics Extensional tectonics is concerned with the structures formed by, and the tectonic processes associated with, the stretching of a planetary body's crust or lithosphere. Deformation styles The types of structure and the geometries formed depend on ...

since the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

(i.e. about the last five million years), with most of the

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 ...

s being normal in type and NW-SE trending. The extension is due to the

back-arc basin A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most of ...

in the

Tyrrhenian Sea The Tyrrhenian Sea (; it, Mar Tirreno , french: Mer Tyrrhénienne , sc, Mare Tirrenu, co, Mari Tirrenu, scn, Mari Tirrenu, nap, Mare Tirreno) is part of the Mediterranean Sea off the western coast of Italy. It is named for the Tyrrhenian pe ...

opening faster than the

African Plate The African Plate is a major tectonic plate that includes much of the continent of Africa (except for its easternmost part) and the adjacent oceanic crust to the west and south. It is bounded by the North American Plate and South American Plat ...

is colliding with the

Eurasian Plate The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and ...

. To the northeast of the Apennine chain, the foreland is in contrast affected by W-E trending strike-slip to oblique-slip faults.

Damage

The area affected covered about , lying between the

Garigliano River The Garigliano () is a river in central Italy. It forms at the confluence of the rivers Gari (also known as the Rapido) and Liri. Garigliano is actually a deformation of "Gari-Lirano" (which in Italian means something like "Gari from the Liri"). ...

, the

Crati The Crati is a river in Calabria, southern Italy. It is the largest river of Calabria and the third largest river of southern Italy after the Volturno and the Sele. In classical antiquity it was known as the Crathis or Crater (Greek: ). Geograp ...

valley, and the

Biferno The Biferno is a river of Molise, in southern Italy. Its source is in the ''comune'' of Bojano and during the first few kilometres of its course, it receives the waters of numerous streams which flow from the Matese mountains. It runs through seve ...

and Murgia areas, including parts of high

, the

Vulture area The Vulture ( it, Il Vulture, italic=no, ), also known as the Vulture-Melfese or Vulture-Alto Bradano is a geographical and historical region in the northern part of the province of Potenza, in the Basilicata region of Italy. Geography The are ...

, the Sannio Hills,

Salerno Salerno (, , ; nap, label= Salernitano, Saliernë, ) is an ancient city and ''comune'' in Campania (southwestern Italy) and is the capital of the namesake province, being the second largest city in the region by number of inhabitants, after ...

Naples Naples (; it, Napoli ; nap, Napule ), from grc, Νεάπολις, Neápolis, lit=new city. is the regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 909,048 within the city's adminis ...

, the

province of Matera The province of Matera ( it, Provincia di Matera; Materano: ) is a province in the Basilicata region of Italy. Its capital is the city of Matera. It has an area of and a total population of 201,133; the city Matera has a population of 61,204. T ...

and the highest parts of

. 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. The death toll was reported as 1,404, with some three quarters of the victims being in the

province of Avellino The Province of Avellino ( it, Provincia di Avellino) is a province in the Campania region of Southern Italy. The area is characterized by numerous small towns and villages scattered across the province; only two towns have a population over 20,0 ...

. 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.

Characteristics

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 Intensity may refer to: In colloquial use *Strength (disambiguation) *Amplitude * Level (disambiguation) * Magnitude (disambiguation) In physical sciences Physics *Intensity (physics), power per unit area (W/m2) *Field strength of electric, ma ...

of X (''Very destructive'') on the

European Macroseismic Scale The European macroseismic scale (EMS) is the basis for evaluation of seismic intensity in European countries and is also used in a number of countries outside Europe. Issued in 1998 as an update of the test version from 1992, the scale is referred ...

was recorded at Aquilonia Vecchia,

Lacedonia Lacedonia ( Irpinian: ) is a ''comune'' in the province of Avellino, Campania region, southern Italy, overlooking the Osento River which flows into the Lago di San Pietro (Lake of Saint Peter), an artificial lake. The town is part of the Roman ...

and

Villanova del Battista Villanova del Battista is a town and ''comune'' in the province of Avellino, Campania, southern Italy. Located in Irpinia historical district between the Ufita Valley and Daunian Mountains, the town is part of the Roman Catholic Diocese of Ariano ...

. Intensities of IX (''Destructive'') were recorded at Anzano degli Irpini,

Scampitella Scampitella (Irpino: ) is a town and ''comune'' in the province of Avellino, Campania, Italy. Located upon the Apennines watershed between the Ufita Valley and Daunian Mountains, the town is part of the Roman Catholic Diocese of Ariano Irpino-La ...

Castel Baronia Castel Baronia is a town (comune) in the province of Avellino, Campania Campania (, also , , , ) is an administrative Regions of Italy, region of Italy; most of it is in the south-western portion of the Italian peninsula (with the Tyrrhenian Se ...

Melfi Melfi (Neapolitan language, Lucano: ) is a town and ''comune'' in the Vulture area of the province of Potenza, in the Southern Italian region of Basilicata. Geographically, it is midway between Naples and Bari. In 2015 it had a population of 17,7 ...

Montecalvo Irpino Montecalvo Irpino is a town and ''comune'' in the province of Avellino, Campania, southern Italy. Located upon a hill oversighting Ufita Valley, the town is known for its bread (), which is granted PAT quality mark, and DOP olive oil. In th ...

Rocchetta Sant'Antonio Rocchetta Sant'Antonio ( Foggiano: or ) is a town and ''comune'' in the province of Foggia in the Apulia region of southeast Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern ...

and

Trevico Trevico is a town and ''comune'' in the province of Avellino, Campania, southern Italy. Located in the Apennines upon a steep hill at 3,576 feet (1,090 m) altitude, Trevico is the highest inhabited place in Campania. Its main produce are hams, ch ...

. 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.

References

External links

* {{DEFAULTSORT:1930 Irpinia Earthquake Earthquakes in Italy Irpinia Earthquake, 1930 Irpinia Earthquake, 1930 July 1930 events 1930 disasters in Italy

Tectonic setting

Damage

Characteristics

See also

References

External links