The L’Aquila seismic sequence - April 2009
On April 6 th 2009 an earthquake (Ml=5.8; Mw= 6.2) occurred at 03:33 a.m. ( local time) near L’Aquila as a result of normal faulting on a NW-SE oriented structure about 15 km long. The fault dips toward SW and the town of L’Aquila lies on the hanging wall. The seismic sequence includes hundreds of events located in real time by the seismologists at INGV monitoring room, using data from both the National seismic network and from the satellite emergency network installed in the epicentral area.
During the days following the main event the Italian National Seismic Network located several hundreds of aftershocks (Figure1). Three large aftershocks (Ml 4.8, 4.7 and 5.3) occurred on April 7th near L’Aquila and south-east of the town ( close to Onna, Fossa, Ocre villages). None of the aftershocks of April 8th was larger than Ml 4. On April 9th a Ml 5.1 was located to the north of L’Aquila, close to Barete, Pizzoli, Campotosto. We had more than 30 aftershocks 3.5<Ml< 5., and several thousands events of lower magnitude.
The area interested by seismicity is about 30 km long and strikes in the NW-SE direction, parallel to the Apennine mountain axis and to the main fault structures known in the area.
The seismicity is confined in the upper crust: the northern events are located above 12 km depth, while the southernmost Ml 5.3 aftershock occurred at 15 km depth.
The mainshock occurred on a fault about 15 km long having a NW-SE strike and a SW dip.
UPDATED INFORMATION about the sequence - June 27, 2009
LOCATION of April 6, 2009 earthquake updated with all the available data
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6 Aprile 2009 3.33 Reset - Sito ad aggiornamento aperiodico ai sensi della Legge n. 62 del 07.03.2001 - Le fotografie firmate contenute nel sito sono di propriet degli autori, per il loro uso e la loro pubblicazione necessario chiederne espressa autorizzazione. Alcune delle foto presenti sono state prese da Internet, e quindi valutate di pubblico dominio. Email: info@laquilanuova.org
