Macroseismic survey of the April 6, 2009 L’Aquila earthquake (central Italy)
Abstract
On April 6, 2009, at 01:33 GMT, central Italy has been hit by a strong earthquake (Ml 5.8, Mw 6.3) representing the mainshock of a seismic sequence of over 20.000 aftershocks recorded in about five months. The event, located in the inner of the Abruzzi region just a few kilometres SW of the town of L’Aquila, has produced destructions and heavy damage in a 30 km wide area and was felt in almost Italy, as far as the coasts of Slovenia, Croatia and Albania. In all, 308 people lost their lives. A macroseismic survey was carried out soon after the earthquake by the QUEST group (QUick Earthquake Survey Team) with the aim to define, for Civil Protection purposes, the damage scenario over a territory which is densely urbanised. Damage generally depended on the high vulnerability of the buildings both for problems related to the old age of the buildings - it is the case of the historical centre of l’Aquila - and to site effects, as in some quarters of the town and in the nearby villages. Rubble-stone and masonry buildings suffered heaviest damage - a lot of old small villages almost entirely collapsed - while reinforced concrete (RC) frame buildings generally experienced moderate structural damage except in particular condition. The macroseismic effects reached intensity IX-X MCS (Mercalli-Cancani-Sieberg scale) at Onna and Castelnuovo, while many others villages reached VIII-IX MCS, amongst which the historical centre of L’Aquila. This town was investigated in detail due to the striking difference of damage between the historical centre and the more recent surrounding areas. In all, more than 300 localities have been investigated (Galli and Camassi, 2009). The earthquake has also provoked effects on natural surroundings (EMERGEO WG, 2009). Two types of phenomena have been detected: (i) surface cracks mainly observed along previously mapped faults and (ii) slope instability processes, such as landslides and secondary fractures. The pattern of macroseismic effects looks like that of the 1461 event, which produced heavy damages in L’Aquila and destructions in the surrounding south-eastern areas. Historical sources report, also in this case, many aftershocks, some of them very strong. References EMERGEO Working Group. (2009): Rilievi geologici nell’area epicentrale della sequenza sismica dell’Aquilano del 6 aprile 2009. Quaderni di Geofisica, 70, pp. 1-55. Galli P. and Camassi R. (eds.), (2009): Rapporto sugli effetti del terremoto aquilano del 6 aprile 2009, Rapporto congiunto DPC-INGV, 12 pp. available on the web at http://portale.ingv.it/real-time-monitoring/quest/macrodef_sito.pdf
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.U23A0025C
- Keywords:
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- 7200 SEISMOLOGY