GIS procedure to evaluate the relationship between the period of construction and the outcomes of compliance with building safety standards. The case of the earthquake in L’Aquila (2009)

The earthquake (Ml=5.8; Mw=6.3) that shook L’Aquila (Abruzzo region, Italy) on 6 April 2009 and caused huge widespread damage in the other 56 municipalities of the seismic crater has also provided important input to reflect proactively on the need to avoid the repetition of similar tragedies, learning from the ca-lamities that have occurred. In fact, L’Aquila and the other municipalities hit by the earthquake represent an open-air analysis laboratory to reveal and directly see the weak points of the different buildings on the field which did not adequately resist the shocks. In order to provide important data for social utility, in this paper we illustrate the steps which constitute a GIS procedure that we have thought in order to evaluate the relationship between the period of construction and the outcomes of compliance with building safety stand-ards. Through sequential activities which have enabled us to also produce three-dimensional scenarios – of immediate communicative impact and able to show details for interdisciplinary analysis and strategical planning – we have portrayed the urban evolution of L’Aquila per period of construction and mapped the level of damage to the buildings. The relational analysis and quantitative data have permitted us to show that in the case of L’Aquila the major percentages of “unusable buildings”, and also these together with “condemned buildings due to external risks” concern the structures erected until 1955 and then in the 1956-1975 period, followed by the ones constructed in the periods of 1976-1988 and 1989-1994. Similar results, in conjunction with other specific information, can offer the possibility to define and apply the consolida-tion measures necessary to tackle future earthquakes in an appropriate way, without a passive sense of res-ignation and with a deeper awareness of seismic risk.