The New Auditorium of the Castle in l’Aquila, designed by Architect Renzo Piano, financed by the Province of Trento, temporarily relieves the Concert Hall of the 16th century Spanish fort, unfitted for use by the earthquake of April 6, 2009. The new hall is an oblique cube with 18m-long edges.The principles upon which the overall design is based are seismic action drop and building mass reduction. The choice of using wood comes from both architectural and structural reasons. Wood is a lightweight but very strong material. Little mass reduces the danger in case of earthquake. The Hall has a limited dissipative behaviour, because of its shape and of the chosen structural technology. There- fore we have adopted a base isolation system, composed by sixteen elastomeric isolators that reduce the seismic force by about 80%. The two additional buildings are used by the audience and the orchestra and are designed with the standard cross- lam panels building method, as an example of the application of lightweight and innovative earthquake-resistant techniques that can be used for the safe reconstruction of the Town too.
L’Aquila
Reconstruction strategies after the Friuli Earthquake in 1976
This paper is available in Italian only.
Prevedere i terremoti: la lezione dell’Abruzzo
During the first three months of 2009 a sequence of small shocks M ≤ 2.7 occurred near the city of L’Aquila. Towards the end of March the frequency of the shocks was rising and on March 30 an M = 4 earthquake occurred. A Committee of experts was charged to examine the likelihood of an impending strong earthquake. On March 31 the Committee concluded that nowadays no short-term prediction is possible and whatever proposed forecasting is not founded on a scientific basis. In this paper some critical comments are presented both on the content of this conclusion and on the method used by the Committee for the analysis. We observe that foreshocks are considered by the scientific community as a very real precursory phenomenon, even though with a high probability of false alarm. Statistical researches carried out in Italy and in California found that this probability is of the order of 0.98, so that the probability of a strong earthquake after the foreshock is of the order of 0.02. In absolute terms the risk is very small, however it is more than 100 times larger than the basic risk of the zone. As far as the method is concerned the analysis should take into account, besides all other possible seismolgical symptoms, also the social scenario in which the foreshock happens. Some results of theoretical researches on alarm systems based on more than one precursor are then summarized. They show how, starting from the characteristics of the precursors, it is possible to define new quantities that are helpful when the matter is to issue a public warning. It is a typical case of decision in uncertain conditions (small probabilities, heavy possible damage) in which an important role is played by social repercussions.
For this paper is available an extended abstract after the text in Italian