Description
At the surface, seismic shaking can be modified in amplitude, frequency and duration according to local subsurface characteristics and topography. The technical reference document describing these processes is the Seismic Microzonation Guidelines and Criteria, a text approved in 2008 by the Conference of the Regions and Autonomous Provinces and the Presidency of the Council of Ministers (Civil Protection Department). Seismic microzonation studies are an important tool for seismic risk prevention on a national scale, which is why a special 'Technical Commission for the support and monitoring of seismic microzonation studies' was established, of which the Autonomous Province of Trento is also a member.
The main objectives of seismic microzonation are to provide useful information for spatial planning and governance, design, emergency planning and post-earthquake reconstruction. Seismic microzonation can be subdivided into three in-depth levels, characterised by progressively increasing cognitive stages, starting from a qualitative or semi-quantitative description of phenomena up to their specific and detailed quantitative definition. These studies are strictly interdisciplinary in nature, as they require the expertise of geologists, seismologists, geophysicists, geotechnicians and engineers.
The very first studies conducted in the past on the provincial territory concerned an earthquake damage zonation in the Basso Sarca area (Riva del Garda; year 1996) in collaboration with the Politecnico di Milano, as well as experimental instrumental measurement studies in the northern area of Trento (years 1997-1999) and in Val di Sole (Monclassico; years 2000-2001). In 2012, a first version of the First Level Seismic Microzonation Map was drawn up for the entire Trentino territory, which qualitatively defines zones of homogeneous seismic behaviour, taking into account possible topographic or stratigraphic amplifications. In addition, Third Level Seismic Microzonation Studies have so far been carried out in Canazei (Val di Fassa) and Caldes (Val di Sole) and, in more recent years, in the Basso Sarca area. The third-level study in the Rovereto area is planned for the period 2024-2027.
Within the activities aimed at updating the First Level Seismic Microzonation Map, the Survey Map and the Geological-Technical Map of the entire provincial territory were recently completed. This map, drawn up in accordance with the Standards for Computerised Representation and Archiving of Seismic Microzonation, was created using the data and information contained in the currently available geological and geophysical databases.
Local seismic response analyses are also available for some buildings and structures in the provincial territory which, due to their type and use, are classified in use class III (buildings whose use involves significant crowding) and IV (buildings with important public or strategic functions) (according to Ministerial Decree 14.01.2008). This is in order to more reliably define the seismic action at such works.