Evaluation of Damages to the Architectural Heritage of Naples as a Result of the Strongest Earthquakes of the Southern Apennines

Abstract

The city of Naples (Campanian region, Southern Italy) has been hit by the strongest earthquakes located inside the seismogenic areas of the Southern Apennines, as well as by the volcano-tectonic earthquakes of the surrounding areas of the Campi Flegrei, Ischia and Vesuvius volcanic districts. An analysis of the available seismic catalogues shows that in the last millennium, more than 100 earthquakes have struck Naples with intensities rating I to III on the Mercalli–Cancani–Sieberg (MCS) scale over the felt level. Ten of these events have exceeded the damage level, with a few of these possessing an intensity greater than VII MCS. The catastrophic earthquakes of 1456 (I0 = XI MCS), 1688 (I0 = XI MCS) and 1805 (I0 = X MCS) occurred in the Campania–Molise Apennines chain, produced devastating effects on the urban heritage of the city of Naples, reaching levels of damage equal to VIII MCS. In the 20th century, the city of Naples was hit by three strong earthquakes in 1930 (I0 = X MCS), 1962 (I0 = IX MCS) and 1980 (I0 = X MCS), all with epicenters in the Campania and Basilicata regions. The last one is still deeply engraved in the collective memory, having led to the deaths of nearly 3000 individuals and resulted in the near-total destruction of some Apennine villages. Moreover, the city of Naples has also been hit by ancient historical earthquakes that originated in the Campanian volcanic districts of Campi Flegrei, Vesuvio and Ischia, with intensities up to VII–VIII MCS (highest in the Vesuvian area). Based on the intensity and frequency of its past earthquakes, the city of Naples is currently classified in the second seismic category, meaning that it is characterized by “seismicity of medium energy”. In this paper, we determine the level of damage suffered by Naples and its monuments as a result of the strongest earthquakes that have hit the city throughout history, highlighting its repetitiveness in some areas. To this aim, we reconstructed the seismic history of some of the most representative urban monuments, using documentary and historical sources data related to the effects of strong earthquakes of the Southern Apennines on the city of Naples. The ultimate purpose of this study is to perform a seismic macro-zoning of the ancient center of city and reduce seismic risk. Our contribution represents an original elaboration on the existing literature by creating a damage-density map of the strongest earthquakes and highlighting, for the first time, the areas of the city of Naples that are most vulnerable to strong earthquakes in the future. These data could be of fundamental importance to the construction of detailed maps of seismic microzones. Our study contributes to the mitigation of seismic risk in the city of Naples, and provides useful advice that can be used to protect the historical heritage of Naples, whose historical center is a UNESCO World Heritage site.

Keywords

• Naples (Southern Italy), historical earthquakes
• Southern Apennines
• seismic hazard