A research team from the University of Trento has developed digital maps of seismic risk in the Riva del Garda area, in the province of Trento. Here, the December 13, 1976at 6:24 an earthquake of magnitude 4.4 (which was later renamed the “Santa Lucia earthquake”) caused serious damage. Almost fifty years later, thanks to the analysis of a large amount of historical, geological and satellite data and computer simulations, it was possible to develop a new model for risk assessment particularly accurate in the affected area. The objective is to contribute to the prevention of the most serious consequences of any future earthquakes.
The creation of seismic risk maps
On 13 December 1976, at 6.24 in the morning, a strong tremor surprised the population of Riva del Garda, and more generally of Alto Garda and the Ledro valley. There were no victims, but some injured, hundreds of displaced people and extensive damage for a total of 10 billion lire: most of the historic buildings were damaged, with damage also to the town hall, schools and churches. The researchers’ work, financed by the Autonomous Province of Trento, started from one territory mapping to analyze the three elements that define seismic risk: the dangeri.e. the probability that a certain level of ground shaking will occur in a certain time interval; The exposed valuewhich concerns for example the number of inhabitants and the value of buildings; there vulnerabilitythat is, the predisposition of structures and people to suffer damage. In particular, the research took into account the local geological featureswhich can amplify the effects of an earthquake (seismic microzonation). In this way it was possible to build digital maps of seismic risk very accurate. Seismicity in the Alto Garda area was found to be medium widespread, with the risk of phenomena of amplification of seismic waves in the historic center of Riva.
The simulation of the 1976 earthquake
To calibrate the developed map model, the researchers have recreated the 1976 earthquake with a computer simulation which also included the reproduction of the damage recorded that day. The results were then verified by comparing them with satellite data, historical documents and geological surveys. The model was further validated with the 2019 earthquake in Vallarsa, in the province of Trento. The aim of the research is to contribute to the monitoring of the structures present in the area, one correct territorial planning and to preparation of emergency plans adequate, which guarantee the safety of the population. In particular, the work highlights the need to reorganize emergency plans, reviewing escape routes in order to guarantee rescue operations. The ultimate goal is to achieve a single digital system of information collection and management, with the possibility of accessing seismic risk maps for all citizens, who in this way could learn more about the territory in which they live and the risks to which it is subject.
