Earthquake scenarios and seismic input for cultural heritage: applications to the cities of Rome and Florence

TL;DR

This paper discusses the use of scenario-based seismic hazard assessment, especially neo-deterministic methods, for protecting cultural heritage in cities like Rome and Florence, emphasizing realistic ground motion estimates over probabilistic models.

Contribution

It introduces a neo-deterministic approach for seismic hazard assessment tailored for cultural heritage preservation, applied specifically to Rome and Florence.

Findings

Scenario earthquakes provide upper bounds for ground motion levels.

Neo-deterministic methods generate realistic ground motion time series.

Application to Rome and Florence demonstrates effectiveness in seismic microzoning.

Abstract

For historical buildings and monuments, i.e. when considering time intervals of about a million year (we do not want to loose cultural heritage), the applicability of standard estimates of seismic hazard is really questionable. A viable alternative is represented by the use of the scenario earthquakes, characterized at least in terms of magnitude, distance and faulting style, and by the treatment of complex source processes. Scenario-based seismic hazard maps are purely based on geophysical and seismotectonic features of a region and take into account the occurrence frequency of earthquakes only for their classification into exceptional (catastrophic), rare (disastrous), sporadic (very strong), occasional (strong) and frequent. Therefore they may provide an upper bound for the ground motion levels to be expected for most regions of the world, more appropriate than probabilities of exceedance in view of the long time scales required for the protection of historical buildings. The neo-deterministic approach naturally supplies realistic time series of ground motion, which represent also reliable estimates of ground displacement readily applicable to seismic isolation techniques, useful to preserve historical monuments and relevant man made structures. This methodology has been successfully applied to many urban areas worldwide for the purpose of seismic microzoning, to strategic buildings, lifelines and cultural heritage sites; we will discuss its application to the cities of Rome and Florence.