The seismicity of the Italian peninsula is linked to its particular geographical position, because it is located in the area of convergence between the African and Eurasian plates and is subjected to strong compressive thrusts. Even if many earthquakes are not perceived by the population because they are characterized by a low magnitude, these do not escape the experts who work 24 hours a day in the INGV Operational Surveillance Rooms. To understand the characteristics of the seismicity of 2019, we interviewed Maurizio Pignone, geologist of the Institute, who, in addition to telling us what happened over the past year, provided us with precious resources to keep up to date.
Maurizio, how many earthquakes were recorded by the National Seismic Network in 2019?
During 2019 thanks to the 16584 earthquakes have been recorded in Italy and in the surrounding areas. Our researchers and technicians, on shift in the Surveillance rooms of the INGV 24 hours a day, they detected an average of more than 45 events a day, practically one every 30 minutes.
Where did the strongest seismic events occur?
The strongest events were located outside the national territory. Most seismic events of magnitude 5.0 or greater occurred in Albania during the. In this case but in the following hours and days there were four earthquakes ranging in magnitude from 5.1 to 5.4. The same area was also hit in September by two other events of magnitude 5.4 and 5.2. Furthermore, on 26 November an earthquake measuring 5.3 was located in Bosnian territory, while in July an earthquake measuring 5.0 occurred off the coast of Algeria.
What was the strongest seismic event of 2019 in Italy?
In December, an area in the province of Florence, about 20 km from the Tuscan capital, was affected by numerous seismic events. In particular, in the night between 8 and 9, an earthquake measuring 4.5 was recorded with its epicenter between the municipalities of Scarperia and San Piero and Barberino del Mugello. This was the strongest event of 2019 in Italy, and it was felt throughout the Tuscan-Emilian Apennines area, in particular in the province of Florence and throughout the northern part of Tuscany, also causing some damage. Other events took place in the following days and throughout the month of December: a total of over 230 occurred, of which 13 with a magnitude greater than or equal to 3.0.
And what about seismic events of lower magnitude?
About 90% of the earthquakes located in Italy in 2019 had a magnitude of less than 2.0 and most of the episodes were not felt by the population, except in the case of very superficial hypocentres and close to inhabited areas.
How was the frequency of earthquakes in 2019 compared to recent years?
Compared to the last three years, the number of earthquakes located in 2019 is decreasing, especially if we compare it with the events of 2016 and 2017. Already since 2018, the contribution of seismic events determined by, which began on August 24, 2016, was in sharp decline; for 2019 this contribution was further reduced, even if as a percentage it still represents a very high value compared to the total seismicity in Italy: about 40%.
And what about the new seismic sequences? Where did those that started in 2019 take place?
The seismic sequences that began in 2019 occurred in various areas of our territory and were short-lived, at most a few tens of days, with low magnitude values. In addition to the Mugello sequence we have mentioned, we recall the Balsorano sequence, in the province of L'Aquila. On November 7, a, on the border with the province of Frosinone. The earthquake was felt in a large region of central Italy and in the following days there were numerous aftershocks in the area. From November 7 to December 31, we recorded over 170 low-magnitude earthquakes and only one event with a magnitude greater than 3.0. Also in the province of Cosenza in the past year numerous earthquakes were recorded, about 115, of different magnitudes and hypocentral depths. In this sequence, the strongest and most felt event took place on October 25, it was of magnitude 4.4 and occurred at a depth of twelve kilometers. The other events were of low magnitude, with only six reaching or exceeding magnitude 3.0. Finally, we recall the sequence in the Benevento area: in the months of November and December, a few kilometers south of the city of Benevento, numerous seismic events took place, located between the municipalities of San Leucio del Sannio and Ceppaloni. Particularly on the days of and on 16 December, the National Seismic Network recorded several earthquakes with magnitudes between 3.0 and 3.9 and, among these events, the strongest earthquake was that of. This event was felt between the provinces of Benevento and Avellino and in some places in the nearby provinces of Naples and Salerno. In total, about 21 earthquakes were located in the area from November 31 to December 70.
Inside the INGVterremoti blog it is possible to ask questions an interactive map to get the complete picture of the events of 2019. What exactly is it about?
It is a dashboard, an application where earthquakes with a magnitude greater than or equal to 2.0 are represented, classified and themed according to their magnitude. Each event can be interrogated by the user who in this way displays the relative hypocentral parameters. Infographics are available in the application that show, for an area chosen by the user, the total number of earthquakes located in 2019, their maximum magnitude and their distribution during the year. But that is not all! It is possible to activate the TIME SLIDER to start a space-time animation of seismicity from 1 January 2019 or from other time intervals of your choice.
Where can we find these precious digital resources that help us better understand seismic phenomena?
is posted in the gallery while in the it is possible to find in-depth information on the events of the year. Finally browsing the the user can consult constantly updated material to find out what is happening in Italy and in the world.