The 1968 Belice earthquake sequence took place in

Sicily (man) it, Siciliana (woman) , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = Ethnicity , demographics1_footnotes = , demographi ...

between 14 and 15 January. The largest shock measured 5.5 on the

moment magnitude scale The moment magnitude scale (MMS; denoted explicitly with or Mw, 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. It was defined in a 1979 pape ...

, with five others of magnitude 5+. The maximum perceived intensity was X (''Extreme'') on the Mercalli intensity scale. The

earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...

sequence, centred between the towns of

Gibellina Gibellina ( Sicilian: ''Jibbiddina'', Arabic: "little mount" - جبل صغير) is a small city and ''comune'' in the Province of Trapani, the mountains of central Sicily, Italy. It was destroyed by the 1968 Belice earthquake. The new city, G ...

Salaparuta Salaparuta is a town and ''comune'' in South-Western Sicily, Italy, in the valley of the Belice river, administratively part of the province of Trapani Trapani ( it, Provincia di Trapani, scn, Pruvincia di Tràpani; officially ''Libero consorz ...

and

Poggioreale Poggioreale ( Sicilian: ''Poggiuriali'') is a ghost town and '' comune'' in the province of Trapani, western Sicily, southern Italy, located in the Belice valley. The Economy was mostly based on agriculture and fruit cultivation. Earthquak ...

, killed at least 231 people, possibly more than 400, with between 632 and about 1,000 injured and left 100,000 homeless. It is known in Italy as Terremoto del Belice.

Tectonic setting

Sicily lies on the complex

convergent plate boundary A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a ...

between 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 Plate ...

and 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 ...

. The geology of the western part of the island is dominated by the Gela Nappe, a thin-skinned

fold and thrust belt A fold and thrust belt (FTB) is a series of mountainous foothills adjacent to an orogenic belt, which forms due to contractional tectonics. Fold and thrust belts commonly form in the forelands adjacent to major orogens as deformation propagates o ...

. The Gela Nappe consists of

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...

age sedimentary rocks deposited in the earlier

foredeep A foreland basin is a structural basin that develops adjacent and parallel to a mountain belt. Foreland basins form because the immense mass created by crustal thickening associated with the evolution of a mountain belt causes the lithosphere ...

, thrust up onto the thick carbonate sequence of the Pelagian-Hyblean Platform of the African Plate.

Earthquake

There was a sequence of six M 5+ earthquakes, making this western Sicily's largest historical seismic event, beginning with a M 5.2 shock at 12:28 on the 14 January, followed by a M 5.1 event at 13:15 on the same day and a M 5.2 event at 01:33 on 15 January, the mainshock at 02:01, and two M 5.2 events at 16:42 on 16 January and at 09:56 on 25 January. The greatest perceived intensity on the Mercalli scale was X (''Extreme'') at Gibellina, Montevago and Salaparuta. Intensities at Poggioreale, Santa Margherita di Belice, Santa Ninfa, Partanna and Salemi reached IX (''Violent'') on the scale. Poggioreale ruderi2

The focal mechanisms of the mainshock and the two magnitude 5+ aftershocks are consistent with thrusting on faults trending west–east, although an alternative solution has been proposed for the mainshock of right lateral

transpression In geology, transpression is a type of strike-slip deformation that deviates from simple shear because of a simultaneous component of shortening perpendicular to the fault plane. This movement ends up resulting in oblique shear. It is generally v ...

on a NNW-SSE trending fault.

Damage

The main area of damage was centred on the valley of the Belice, with worst affected towns being

Santa Ninfa Santa Ninfa is a town and ''comune'' in the province of Trapani, Sicily, southern Italy. History Santa Ninfa was founded in 1605 by Luigi Arias Giardina who, with approval of King Philip III of Spain Philip III ( es, Felipe III; 14 April 1 ...

Partanna Partanna is a town and ''comune'' in province of Trapani, south-western Sicily, southern Italy. It is south-east of Trapani Trapani ( , ; scn, Tràpani ; lat, Drepanum; grc, Δρέπανον) is a city and municipality (''comune'') on t ...

Montevago Montevago ( Sicilian: ''Muntivau'') is a ''comune'' (municipality) in the Province of Agrigento in the Italian region Sicily, located about southwest of Palermo and about northwest of Agrigento. Montevago borders the following municipalities: ...

Santa Margherita di Belice Santa Margherita di Belice ( Sicilian: ''Santa Margarita'') is a town in the Province of Agrigento in the Italian region of Sicily. It lies in southwest Sicily, above sea level, near where the borders of the Province of Agrigento, Province of Tr ...

Vita Vita or VITA (plural vitae) is Latin for "life", and may refer to: * ''Vita'', the usual start to the title of a biography in Latin, by which (in a known context) the work is often referred to; frequently of a saint, then called hagiography * Vit ...

Salemi Salemi is a town and ''comune'' in southwestern Sicily, Italy, administratively part of the province of Trapani. History Salemi is where Giuseppe Garibaldi announced the annexation of Sicily on May 14, 1860, as part of the Expedition of the T ...

, and Camporeale also suffered significant damage. The earthquakes on 14 January did little damage, but many of the inhabitants spent the following night sleeping outside, during which the most damaging of the shocks occurred, which probably greatly reduced the number of casualties. The official death toll was 231 with a further 623 injured. Other estimates give more than 400 dead with over 1,000 injured. An estimated 100,000 people were made homeless by the earthquakes. The worst affected buildings were of unreinforced masonry construction that used irregular stones with weak mortar and had roofs consisting of heavy tiles resting on wooden beams. Such buildings collapsed completely in many cases. Houses with load-bearing walls made of regular stone or concrete blocks and better quality mortar performed better, although some were badly damaged. The most modern buildings that used reinforced concrete frames generally suffered little damage.

Aftermath

The immediate relief effort was hampered by a lack of disaster relief planning at both local and provincial levels, excessive bureaucracy, a lack of supplies close to the affected areas and a tendency of refugees to treat outsiders with suspicion. One year after the earthquakes, many hundreds of people were still living in tents and many of the prefabricated housing units had yet to appear, despite having been paid for; no work had begun on providing permanent housing. Two-thirds of refugee families had still not received their government grant. Nine years after the earthquake, none of the refugees had been placed in new housing, leaving 60,000 still living in temporary accommodation. The towns of Poggioreale, Gibellina, Vita, Santa Margherita di Belice and Salaparuta were eventually rebuilt in new locations.

References

External links

* * {{DEFAULTSORT:Belice Earthquake, 1968 1968 Belice 1968 earthquakes 1968 in Italy 1968 January 1968 events in Europe Earthquake clusters, swarms, and sequences 1968 disasters in Italy