Learning from Construction Failures due to the 2009 L'Aquila, Italy, Earthquake

An earthquake sequence struck the province of L'Aquila (central Italy) leaving 305 dead, about 1,500 injured, and 29,000 homeless. Hundreds of low-intensity events occurred between January and March, 2009. The mainshock took place on April 6, 2009, and its epicenter was located at about 6 km southwest of L'Aquila town; three stronger aftershocks happened on April 7 and 9, 2009. This paper focuses on actual performance of older and more recently constructed building structures during the earthquake sequence. After the main seismological characteristics of the sequence are described, the most significant observed damages are analyzed and associated with theoretical failure modes for both reinforced concrete and unreinforced masonry buildings. Since older masonry structures were more seriously damaged, the effects of the earthquake are described with more emphasis to ordinary masonry and cultural heritage buildings (churches, palaces, and castles). In conclusion, a number of lessons may be learned from the L'Aquila earthquake sequence. Several features are highlighted and some proposals are given to upgrade the current methods of structural analysis, as well as the existing codes.