Press release of 9 October 2009 (20 pm)
Today, the National Seismic Network recorded 13 earthquakes in the Frusinate area with a maximum magnitude of ML 2.1 at 4:45 Italian time on 9 October 2009. The analysis of the recorded data shows that the sequence affects an area of about 10 km2 . The spatial distribution of the tremors indicates the activation of a portion of the fault with dip to the SW and plane in the Apennine direction. Do earthquakes affect a depth? between 12 and 8 km. The structure outlined by seismicity? Could it correspond to the fault system of the Alto Sangro valley included, from the point of view of seismicity? historical, between the 1915 earthquake (Avezzano Mw6.7) to the north and the great earthquake of 1349 (M6.6) to the south. Other minor historical earthquakes (1654 and 1922) and the 1984 event (ML5.9) occurred around the structure active today. In the last 20 years the seismicity? in the area ? been scarce and without earthquake swarms.
Press release of 8 October 2009 (13 pm)
Between the evening of 6 October and today, 8 October 2009, some earthquakes of ML ?3.0 were recorded located in a small area in the province of Frosinone. The most common close to the epicentral area (within about 10 km) are: Alvito, Broccostella, Campoli Appennino, Fontechiari, Pescosolido, Posta Fibreno, Sora, Vicalvi, all in the Province of Frosinone. The most earthquakes strong these days took place on October 8 at 02:51 02:53 (Italian time) with ML equal to 3.5 and 3.4, respectively. Other events of ML =3.0 occurred on 6 and 7 October.
In the previous months, the most important events? significant ones took place on 6 August at 15:36 (ML3.9) and on 30 September at 19:52 (ML3.5).
The earthquakes of these days, accompanied by numerous events of minor magnitude, testify to the resumption of activity? microseismic in an area that had shown the beginning of activity? in the last months. The localized events in the area (a total of a dozen ML events between 2.0 and 3.9 and numerous instrumental shocks, including about 100 events in the last 3 days) show a space-time trend of the seismic swarm type. The depths? hypocentral are those typical of the seismic zones of the Apennines (in the first 12 km of the crust).
The seismicity? it affects the area hit by the destructive earthquake of 1349 (intensity X degree) and since then other minor shocks reported in historical catalogs but generally lower than VIII degree. Also the area in question? adjacent to the area affected by the ML 5.9 earthquake of 7 May 1984 (Val di Comino). The activity seismic event that we record takes place in a seismotectonic context where there are potentially active faults capable of earthquakes with a magnitude equal to or greater than 6, and therefore falls within a dangerous area? high seismic. The Municipalities of the Frosinone area where the business is? in progress are included in the I or II seismic class (see:
http://zonesismiche.mi.ingv.it/ e http://www.protezionecivile.it/cms/attach/editor/Classificazione.jpg )
The National Institute of Geophysics and Volcanology is carefully following the evolution of the sequence through the National Seismic Network, which for the area in question has good location accuracy, even at depth. All information on major earthquakes is communicated to the National Civil Protection Department and published on our website: http://www.ingv.it/ and are viewable on http://cnt.rm.ingv.it/earthquakes_map.php. The information on all the earthquakes that we record can be consulted and displayed on paper at: http://iside.rm.ingv.it
