At the moment (7.00 am) numerous aftershocks have been recorded and there are 39 localized seismic events of magnitude equal to or greater than 3.0. The strongest occurred in the Norcia (PG) area with a magnitude of 5.4 at 04:33. (*)
In the table the list of seismic events located after the earthquake of 03:36 Italian time.
The area affected by the aftershocks, which in a first approximation represents the extension of the activated fault, is approximately 25 km and is aligned in the NNW – SSE direction. This dimension is consistent with a magnitude 6 earthquake. The shaking map of the strongest earthquake, calculated with data from the accelerometric networks of INGV and the Civil Protection Department, indicates a relatively higher ground shaking in the North-Western area . The highest peak values recorded are equal to about 45% of g at the National Accelerometric Network station of Arquata del Tronto, 11 km from the epicenter.
The earthquake that occurred last night in the central Apennines area at 3:36 (Italian time) had its epicenter in the province of Rieti (near Accumoli) and also affected the provinces of Perugia, Ascoli Piceno, L'Aquila and Teramo. The municipalities closest to the epicenter are: Accumoli, Amatrice, Arquata del Tronto.
The local magnitude (Richter) of the earthquake is 6.0. The moment magnitude Mw, calculated with the analysis of the waveforms of the National Seismic Network, is equal to 6.0.
According to the questionnaires that have arrived so far on the site http://www.haisentitoilterremoto.it/, last night's earthquake was felt in a large part of central Italy. Below is the map (updated at 06:53) showing the distribution of grievances on the territory on the MCS scale (Mercalli-Cancani-Sieberg).
Map of seismic effect in MCS scale (Mercalli-Cancani-Sieberg) showing the distribution of the effects of the earthquake on the territory as reconstructed from the online questionnaires. The map contains a legend (on the right). The purple star indicates the epicenter of the earthquake, the colored circles refer to the intensities associated with each municipality. The caption above shows the characteristics of the earthquake: date, magnitude (ML), depth (Prof) and local time. The number of questionnaires processed to obtain the map itself is also indicated.
The focal mechanism indicates the movement of an extensional type fault with NNW-SSE oriented planes, in coherence with the distribution of the aftershocks and with the tectonic regime of the Apennines.
The area has been hit by strong earthquakes in the past. The main historical earthquakes occurred in 1639 (Magnitudo 6.2), 1646 (Magnitudo 5.9) and 1703 (Magnitudo 6.9) (source: CPTI15).
In this map, the data of historical earthquakes (squares, source: CPTI11) have been superimposed with those of the seismicity of these hours (circles, source: cnt.rm.ingv.it).
The area affected by today's earthquake falls within the highly dangerous seismic zone that runs along the axis of the Apennine chain.
Seismic hazard map with the events of the current sequence superimposed.
The hypocentral depths of the replicas are modest, almost all within the first 10 km. The seismic room shift workers are locating the main aftershocks of the sequence, currently focusing on the strongest ones. Some teams of researchers and technicians from the Institute are on the ground to install temporary monitoring networks to complement the permanent network.
(*) In this morning's post and on the cnt.rm.ingv.it website, an event of magnitude 5.1 was erroneously reported at 04:32 Italian time, which instead turns out to be an earthquake of magnitude 2.5. This glitch of the localization system occurred due to the large amount of events that occur in the first few minutes after the strongest event. We apologize for the inconvenience.