An earthquake is a sudden phenomenon caused by the movement of the earth’s plates. The surface of the Earth called the earth’s crust is divided into many plates or big, separate pieces of rock.. When two plates move together, this cause an earthquake. The collision between the plates involves the breaking of the rocks at one point, called the fault line.
A main shock can occur during an earthquake, followed by a series of smaller aftershocks.
When the series of tremors are more or less of the same magnitude, it is called a seismic swarm.
The strength of earthquakes is measured in 2 ways:
1) MAGNITUDE, indicates the amount of energy released in the hypocenter. It is measured with the Richter Scale, which goes from 0 to 13 degrees. The measuring instrument is the seismograph.
2) INTENSITY, the major or minor effects caused by the earthquake on the environment and on the structures built by man are evaluated. It is measured with the Mercalli Scale, with values from I to XII, expressed in Roman numerals.
Unfortunately, earthquakes cannot be predicted, but it can only be assumed that in correspondence with a specific fault one will sooner or later occur, as it is thought will happen on the San Andreas Fault, which extends for about 1200 km through California ( in North America), between the North American plate and the Pacific plate.
Sometimes earthquakes happen under the sea. These create big waves called a Tsunami which can cause enormous destruction when it hits land.
We can limit the damage of an earthquake, mainly by respecting the anti-seismic regulations in the construction and renovation of buildings, using more resistant materials and adequate techniques.
And also by dividing the national territory into seismic zones (seismic classification).
Italy is a highly seismic nation. With the exception of Sardinia, part of Puglia, part of the Po Valley and the central-western Alps, where the seismic risk is low, the entire national territory is subject to frequent seismic phenomena.
To identify the seismic risk, Italy was divided into 4 seismic zones:
ZONE 1 – high risk – strong earthquakes can occur,
ZONE 2 – medium risk – fairly strong earthquakes can occur,
ZONE 3 – low risk – modest shaking may occur,
ZONE 4 – minimal risk – possibility of very low seismic damage.
Furci Siculo, the town where I live, is located in zone 1, with a high seismic risk!
Earthquakes in Italy:
Italy is located between 2 large plates, the African and the Eurasian one.
Their movement causes the accumulation of energy that is released in the form of earthquakes of various entities.
Among the most important earthquakes of recent years we remember:
2009, ABRUZZO – On 6 April 2009 at 3:32 am a violent earthquake struck L’Aquila and Abruzzo, causing victims and destruction (magnitude 6.3 degrees).
2016, UMBRIA – On 24 August 2016 at 3:36 am a strong earthquake struck central Italy, wiping out some countries such as Amatrice, Accumoli, Arquata del Tronto and Norcia (magnitude 6 degrees) and causing many victims.
Earthquakes in Sicily:
Sicily is one of the most seismic regions of Italy in terms of frequency and intensity of earthquakes.
In the twentieth century there were 2 disastrous earthquakes.
1908, MESSINA – The night between 27 and 28 December 1908 a strong earthquake with its epicenter in the sea, in the Strait of Messina, destroyed the cities of Messina and Reggio Calabria (maximum intensity XI degree Mercalli scale). The cities were also affected by the tsunami and the casualties and damage to homes were enormous.
1968, VALLE DEL BELICE – It occurred on January 15, 1968 in the area between Trapani, Palermo and Agrigento. Many villages were completely destroyed and 926 people died.
Rules of conduct in the event of an earthquake
If an earthquake arrives and we are in a closed environment (home, school) it is important to take shelter under the table, chairs, beams and protect yourself from falling objects such as glass, chandeliers and plaster; if we are outdoors, we must stay away from balconies, trees and light poles.
It is good to reach the collection point provided for by the Civil Protection Plan for your municipality.