1783 Calabrian earthquakes
Encyclopedia
The 1783 Calabrian earthquakes were a sequence of five strong earthquake
s that hit the region of Calabria
in southern Italy
(then part of the Kingdom of Two Sicilies), the first two of which produced significant tsunami
s. The epicenter
s form a clear alignment extending nearly 100 km from the Straits of Messina to about 18 km SSW of Catanzaro. The earthquakes occurred over a period of nearly two months, all with estimated magnitudes of 5.9 or greater. Estimates of the total number of deaths lie in the range 32,000 to 50,000.
extension
within the Siculo–Calabrian Rift Zone. This 350 km long zone developed within the Apennine chain during the Pleistocene
and takes up WNW-ESE directed extension.
. Many villages were damaged and as many as 180 almost completely destroyed, with more than 25,000 casualties. A tsunami affected the coastline on both sides of the Straits of Messina, destroying the harbour walls at Messina.
Near the epicenter the ground shaking was so intense that people were knocked off their feet and heavy stones were found to be dislodged and upturned. Large landslide
s caused major destruction at Terranova and Molochio
but even well-constructed buildings not thus affected were almost completely destroyed, such as in Oppido Mamertina
and Casalnuovo.
The earthquake is thought to have involved rupturing of the Galatro, Cittanova and Sant'Eufemia faults, which form the southeastern boundary to the Gioia Basin.
The earthquake is thought to have involved rupturing of the Scilla fault, which defines the coast around Scilla.
and Soriano Calabro
.
The earthquake is thought to have involved rupturing of the southern segment of the Serre fault that bounds the Mesima Basin.
The earthquake is thought to have involved rupturing of the northern segment of the Serre fault.
. Landslides were common and sand volcano
es were seen, particularly on the banks of the Amato
river.
This earthquake has not been tied to a particular fault, but a recent re-evaluation of the intensity data indicates that the isoseismal areas
are elongated NE-SW, suggesting faulting of similar trend to that observed for the other earthquakes in the sequence.
{| class=wikitable
! Location!! Date!! Time!! Coordinates !! Magnitude!! Intensity
|-
| near Oppido Mamertina
| February 5
| 12:00
| 38.30°N 15.97°W
| 7.0
| XI
|-
| 7 km NE of Messina
| February 6
| 00:20
| 38.22°N 15.63°W
| 6.2
| VIII–IX
|-
| 3 km SW of Soriano Calabro
| February 7
| 13:10
| 38.58°N 16.20°W
| 6.6
| X
|-
| 2 km SE of Filadelfia
| March 1
| 01:40
| 38.77°N 16.30°W
| 5.9
| IX
|-
| near Vallefiorita
| March 28
| 18:55
| 38.78°N 16.47°W
| 7.0
| X
|-
|}
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
s that hit the region of Calabria
Calabria
Calabria , in antiquity known as Bruttium, is a region in southern Italy, south of Naples, located at the "toe" of the Italian Peninsula. The capital city of Calabria is Catanzaro....
in southern Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
(then part of the Kingdom of Two Sicilies), the first two of which produced significant tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...
s. The epicenter
Epicenter
The epicenter or epicentre is the point on the Earth's surface that is directly above the hypocenter or focus, the point where an earthquake or underground explosion originates...
s form a clear alignment extending nearly 100 km from the Straits of Messina to about 18 km SSW of Catanzaro. The earthquakes occurred over a period of nearly two months, all with estimated magnitudes of 5.9 or greater. Estimates of the total number of deaths lie in the range 32,000 to 50,000.
Tectonic setting
The southwestern part of Calabria and the eastern part of Sicily are areas of active crustalCrust (geology)
In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...
extension
Extensional tectonics
Extensional tectonics is concerned with the structures formed, and the tectonic processes associated with, the stretching of the crust or lithosphere.-Deformation styles:...
within the Siculo–Calabrian Rift Zone. This 350 km long zone developed within the Apennine chain during the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
and takes up WNW-ESE directed extension.
February 5
This earthquake, with an estimated magnitude of 7.0, affected a large area including most of the southern Italian peninsula and shook the whole of SicilySicily
Sicily is a region of Italy, and is the largest island in the Mediterranean Sea. Along with the surrounding minor islands, it constitutes an autonomous region of Italy, the Regione Autonoma Siciliana Sicily has a rich and unique culture, especially with regard to the arts, music, literature,...
. Many villages were damaged and as many as 180 almost completely destroyed, with more than 25,000 casualties. A tsunami affected the coastline on both sides of the Straits of Messina, destroying the harbour walls at Messina.
Near the epicenter the ground shaking was so intense that people were knocked off their feet and heavy stones were found to be dislodged and upturned. Large landslide
Landslide
A landslide or landslip is a geological phenomenon which includes a wide range of ground movement, such as rockfalls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments...
s caused major destruction at Terranova and Molochio
Molochio
Molochio is a comune in the Province of Reggio Calabria in the Italian region Calabria, located about 80 km southwest of Catanzaro and about 40 km northeast of Reggio Calabria...
but even well-constructed buildings not thus affected were almost completely destroyed, such as in Oppido Mamertina
Oppido Mamertina
Oppido Mamertina is a town and comune of the province of Reggio Calabria in Calabria in southern Italy at about 62 kilometres northeast of Reggio Calabria and about 120 kilometres southwest of Catanzaro....
and Casalnuovo.
The earthquake is thought to have involved rupturing of the Galatro, Cittanova and Sant'Eufemia faults, which form the southeastern boundary to the Gioia Basin.
February 6
This magnitude 6.2 event occurred during the night following the first event and struck the area just to the southwest. Most of the damage and casualties appear to have been caused by a tsunami that was set off by a major collapse of Monte Pací into the sea near Scilla shortly after the earthquake. Many of Scilla's residents, frightened by the tremors of the previous day had moved onto the open beach for the night, where they were overwhelmed by the waves. The tsunami caused severe flooding in the town, reaching as far as 200 m inland, and there were more than 1500 deaths.The earthquake is thought to have involved rupturing of the Scilla fault, which defines the coast around Scilla.
February 7
This event occurred at about midday 40 km NE of the first mainshock on the 5th. Severe damage extended 15 km along the front of the Serre Mountains, levelling all the villages between AcquaroAcquaro
Acquaro is a comune in the Province of Vibo Valentia in the Italian region Calabria, located about 50 km southwest of Catanzaro and about 15 km southeast of Vibo Valentia...
and Soriano Calabro
Soriano Calabro
Soriano Calabro is a comune in the Province of Vibo Valentia in the Italian region Calabria, located about 45 km southwest of Catanzaro and about 15 km southeast of Vibo Valentia...
.
The earthquake is thought to have involved rupturing of the southern segment of the Serre fault that bounds the Mesima Basin.
March 1
This earthquake was the weakest of the sequence and caused relatively little damage.The earthquake is thought to have involved rupturing of the northern segment of the Serre fault.
March 28
The final event of the sequence was of similar magnitude to the first and had an epicenter about 20 km east of the fourth, near Borgia in the Catanzaro Basin. The earthquake lasted for about ten seconds, and many villages were destroyed with many hundreds dead in Borgia, Maida and CortaleCortale
Cortale is a comune and town in the province of Catanzaro in the Calabria region of Italy....
. Landslides were common and sand volcano
Sand volcano
A sand volcano or sand blow is a cone of sand formed by the ejection of sand onto a surface from a central point. The sand builds up as a cone with slopes at the sand's angle of repose. A crater is commonly seen at the summit...
es were seen, particularly on the banks of the Amato
Amato
Amato is a comune and town in the province of Catanzaro in the Calabria region of Italy.-History:Amato is one of the oldest towns in Calabria. It is mentioned by the Greek philosopher Aristotle, who calls it "Portus Amati Fluminis" . It is also mentioned by the Roman Pliny the Elder in one of his...
river.
This earthquake has not been tied to a particular fault, but a recent re-evaluation of the intensity data indicates that the isoseismal areas
Isoseismal map
In seismology an isoseismal map is used to show lines of equal felt seismic intensity, generally measured on the Modified Mercalli scale. Such maps help to identify earthquake epicenters, particularly where no instrumental records exist, such as for historical earthquakes...
are elongated NE-SW, suggesting faulting of similar trend to that observed for the other earthquakes in the sequence.
Summary of earthquakes
The earthquake parameters shown below are taken from the CFTI4 online catalogue, the epicentral locations are here related to the nearest large village or town.{| class=wikitable
! Location!! Date!! Time!! Coordinates !! Magnitude!! Intensity
|-
| near Oppido Mamertina
Oppido Mamertina
Oppido Mamertina is a town and comune of the province of Reggio Calabria in Calabria in southern Italy at about 62 kilometres northeast of Reggio Calabria and about 120 kilometres southwest of Catanzaro....
| February 5
| 12:00
| 38.30°N 15.97°W
| 7.0
| XI
|-
| 7 km NE of Messina
| February 6
| 00:20
| 38.22°N 15.63°W
| 6.2
| VIII–IX
|-
| 3 km SW of Soriano Calabro
Soriano Calabro
Soriano Calabro is a comune in the Province of Vibo Valentia in the Italian region Calabria, located about 45 km southwest of Catanzaro and about 15 km southeast of Vibo Valentia...
| February 7
| 13:10
| 38.58°N 16.20°W
| 6.6
| X
|-
| 2 km SE of Filadelfia
| March 1
| 01:40
| 38.77°N 16.30°W
| 5.9
| IX
|-
| near Vallefiorita
Vallefiorita
Vallefiorita is a town and comune in the province of Catanzaro in the Calabria region of Italy.-Geography:The town is bordered by Amaroni, Cenadi, Centrache, Cortale, Girifalco, Olivadi, Palermiti and Squillace....
| March 28
| 18:55
| 38.78°N 16.47°W
| 7.0
| X
|-
|}
Relationship between earthquakes
All the earthquakes in this sequence are thought to be linked by a process of triggering caused by stress redistribution following each individual event.External links
- A revision of the 1783–1784 Calabrian (southern Italy) tsunamis, L. Graziani et al., Natural Hazards Earth Syste Sciences Nr. 6, 1053–1060, 2006