The second shock in the 1962 Irpinia earthquake (terremoto dell'Irpinia del 1962) sequence was the largest and most destructive in a series of earthquakes in the southern Apennines. It occurred on August 21 at 18:19 CET, measuring 6.15 and assigned a maximum intensity of IX (''Violent''). It was preceded by an 5.68

foreshock A foreshock is an earthquake that occurs before a larger seismic event (the mainshock) and is related to it in both time and space. The designation of an earthquake as ''foreshock'', ''mainshock'' or aftershock is only possible after the full se ...

, and a 5.34 aftershock. The earthquakes resulted in nearly 20 fatalities and significant property losses.

Tectonic setting

The central Italian Peninsula is dominated by active extensional tectonics, forming the Apennine Mountains. One explanation is that slab rollback is occurring within the

Adriatic Plate The Adriatic or Apulian Plate is a small tectonic plate carrying primarily continental crust that broke away from the African Plate along a large transform fault in the Cretaceous period. The name Adriatic Plate is usually used when referring ...

as it subducts beneath 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 ...

. Another explanation is because the back-arc basin in the

opening at a faster rate 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 Plate ...

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 ...

. Extensional tectonics in the region have been active since the 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 ...

, mainly accommodated by northwest–southeast striking

normal fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tecton ...

s. The faults associated with large earthquakes on the peninsula are geologically young in age, and rarely rupture the surface. Occasionally, strike-slip events like the

1456 Central Italy earthquakes On December 5, the largest earthquake to occur on the Italian Peninsula struck the Kingdom of Naples. The earthquake had an estimated moment magnitude of 7.19–7.4 , and nucleated near the town of Pontelandolfo in present-day Province of Beneve ...

, as well as the 1971 ( 5.0) and 2012 ( 4.6) moderate earthquakes in the southern Apennine region suggest the dominant style of faulting is not limited to normal dip-slip. Strike-slip faults on the Italian Peninsula are oriented east–west.

Geology

Prior to the occurrence of the large foreshock at 18:09, a series of foreshocks were already present in the afternoon that same day. The mainshock struck at 18:19 with a

moment magnitude 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 ...

of 6.15 and

Richter scale The Richter scale —also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale—is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 ...

magnitude of 6.1 . Very few aftershocks were instrumentally recorded; the largest measured 5.4 . Both the foreshock and mainshock occurred at a depth of 8 km, based on waveform analysis, but this result is still controversial and unreliable. The lack of documented surface ruptures further instigated controversy into the mechanism of the earthquakes. The seismology community debated between strike-slip and normal faulting as the cause. A study in 2016 reevaluated its depth to 9 km, and generated a reliable strike-slip focal mechanism. The epicenters are located between the zone of northwest–southeast trending normal faults and east–west striking strike-slip faults. The earthquake sequence represent strike-slip faulting with small normal components along either east–west or north–south trending faults. The location of the 1962 earthquakes is close to the faults that triggered the 1456 earthquakes.

Impact

The first of three severe shocks occurred at 18:09 local time. While it did not cause any damage, it was felt strong enough to frighten residents in Benevento and Avellino. Many residents were driven out of their homes in fear of further shocks. The second shock was the most destructive and violent. It damaged 68 municipalities across the provinces of Benevento and Avellino. A maximum intensity of IX was assigned in the towns of

Melito Irpino Melito Irpino (Irpino: ) is a town and ''comune'' in the province of Avellino, in the Campania region of south-western Italy. History The remains of the ancient Melito were found in 1880. According to some theories, it could be a suburban villag ...

, Molinara, Reino, and

Sant'Arcangelo Trimonte Sant'Arcangelo Trimonte is a ''comune'' (municipality) in the Province of Benevento in the Italian region Campania, located about 70 km northeast of Naples and about 13 km east of Benevento. Sant'Arcangelo Trimonte was part of Province ...

. These towns sustained heavy damage, with at least 90% of all structures affected. More than 50% of the total buildings affected were a total loss due to the severity of damage or complete destruction. Nearly twenty people died and 16,000 were made homeless.

Aftermath

The

Council of Ministers A council is a group of people who come together to consult, deliberate, or make decisions. A council may function as a legislature, especially at a town, city or county/ shire level, but most legislative bodies at the state/provincial or nati ...

, allocated 2 billion

Italian lira The lira (; plural lire) was the currency of Italy between 1861 and 2002. It was first introduced by the Napoleonic Kingdom of Italy in 1807 at par with the French franc, and was subsequently adopted by the different states that would eventually ...

s for first responders and 400 million for assistance. More than 20,000 tents were erected over a period of next ten days for the homeless. Significant quantities of medical supplies, food and clothing were distributed. More than 2,000 barracks were constructed by civil and military engineers to house homeless. After the earthquakes, there were concerns about the potential for landslides as the shocks had destabalized ground conditions on the nearby hills. As a result, authorities decided to evict the residents of Melito Irpino and Apice. The old medieval Melito Irpino is currently a

ghost town Ghost Town(s) or Ghosttown may refer to: * Ghost town, a town that has been abandoned Film and television * ''Ghost Town'' (1936 film), an American Western film by Harry L. Fraser * ''Ghost Town'' (1956 film), an American Western film by All ...

.Melito Irpino on paesifantasma.it
(Italian ghost towns website)

References

{{Earthquakes in Italy 1962 earthquakes 1962 in Italy 20th century in Campania Disasters in Campania Earthquakes in Italy Province of Benevento Province of Avellino Buried rupture earthquakes

Tectonic setting

Geology

Impact

Aftermath

See also

References