During 2017, the National Institute of Geophysics and Volcanology (INGV) located, thanks to the National Seismic Network (RSN), 44.459 earthquakes in Italy and in the surrounding areas. An average of over 120 events per day, 5 every hour. An earthquake every 12 minutes.
The seismicity map localized in 2017 by the INGV National Seismic Network.
Of the 44.459 detected by the RSN in 2017, approximately 37.000 can be considered replicas of the sequence in central Italy, which began on 24 August 2016 and is still ongoing. The total number is significantly lower than the previous year (about 53.000), but much higher than in 2015 and 2014 (about 15.000 and 24.300 respectively).
Annual number of earthquakes located by INGV from 2012 to 2017
Some numbers for the 2017 earthquakes in and around Italy:
· 5 events of magnitude greater than or equal to 5.0: one of these occurred in Albania, 4 in the Campotosto area (AQ);
· 21 of magnitude between 4.0 and 4.9: 6 of these occurred in the surrounding seas and neighboring countries;
· 370 of magnitude between 3.0 and 3.9: of these, some occurred in the surrounding seas and neighboring countries;
· 4224 of magnitude ≥2.0: of these, some occurred in the surrounding seas and neighboring countries.
Almost 90% of the earthquakes located in Italy in 2017 have a magnitude of less than 2.0, which means that they were probably not felt by the population, with some exceptions (for example in the case of very superficial hypocentres).
The table below shows all the events recorded by the National Seismic Network of magnitude equal to or greater than 4.0 on the national territory.
Other events with a magnitude greater than 4 have been detected by the National Seismic Network in the countries and seas around Italy (especially in Switzerland, Bosnia and the Ionian Sea).
The trend of seismic activity in Italy in 2017 is dominated by the evolution of the sequence in central Italy, as shown in the graph below, which shows the seismic events recorded month by month. To understand the impact of the sequence that began in August 2016 on the overall seismicity, the graph also shows the total number of events located in the national territory (blue columns), as well as the number of events in the sequence area (in red) and the number of events outside the sequence area (in green).
The seismic events recorded month by month in 2017: the total monthly number of events located in the national territory (blue columns), the number of events that occurred in the sequence area in central Italy (in red), the number of events outside the sequence area (in green).
The trend of seismicity outside the area of the sequence (green columns) remains rather constant during all months of the year, with a monthly number of events ranging between 400 and 660. The graph above also points out the the downward trend of the activity relating to the sequence in central Italy (red columns): from about 9.000 events in January to about 1.000 in December 2017.
All earthquakes with magnitude greater than or equal to 2.0 are available in a story maps published in the StoryMaps&Earthquakes gallery.
In the application it is possible to select earthquakes month by month and query them for information on magnitude, date/time and depth.
Link to the INGVterremoti blog:
https://ingvterremoti.wordpress.com/2018/01/22/speciale-2017-un-anno-di-terremoti/