Critical analysis of the damage – Casamicciola earthquake of 21 August 2017
Summary Report Critical Analysis of the damage during the Casamicciola earthquake of 21 August 2017
(Giulio Zuccaro, Francesco Cacace, Stefano Nardone, Mauro Iacuaniello)
Plinivs Study Center Mission of 08.23.2017
The complete report can be downloaded at the link report.
On 08.21.2017 at 8.57.5 pm Italian time, a seismic event with a magnitude of 4.0 and a hypocentral depth of approximately 1.7 km occurred on the island of Ischia. As reported by INGV, the epicenter is located in the municipality of Casamicciola, (40.74° lat.N, 13.90 ° long E).
Due to the very low depth and a marked local amplification effect, the shock recorded rather high acceleration values near the epicenter (0.28 g at the OV-OC9 station, located approximately 0.8 km from the epicenter) and a very rapid attenuation, such that the shock did not cause significant damage in nearby locations, even in the Municipality of Casamicciola itself.
The figure shows the position of the epicenter and the macroseismic intensity as indicated in the report of the ENEA QUEST operational group.
As can be seen in the following map, produced by the Plinivs Study Center following the mission conducted on 08.23.2018, the earthquake caused heavy damage in a rather limited area. The earthquake was felt, with varying intensity, across the entire island, but caused serious damage only in Casamicciola Alta, in particular in the Piazza Maio-La Rita area, and in a small area in the Fango area of Lacco Ameno.
Immediately on the edges of these areas (e.g. in Sentinella, Piazza Bagni and in the area around the Town Hall) there are numerous damaged buildings, but with minor damage and only in rare cases medium damage.
As far as it has been possible to observe, moving further away from the epicentral area (e.g. in the central area of Lacco Ameno and in the Perrone district of Casamicciola), there are no buildings with significant damage nor the activation of damage mechanisms. In the Municipality of Ischia there was no damage, in Ischia Ponte, for example, the earthquake only caused apprehension among the population even if it was not even felt by some.
Obviously, surveys and records of damage and usability are not yet available, so it is not possible to numerically quantify the extent of the damage, but it was possible to carry out an inspection in the affected area, obtaining a precise idea of the seismic impact on the buildings .
The PLINIVS Center has developed a map that reports a first quick estimate of the level of damage observed (according to the E.M.S. 98 classification) on a wide selection of buildings in the area around Piazza Maio, Via Montecito and Via D’Aloisio. Considering the ongoing emergency situation, it was not possible to access the inside of the buildings. Further refinements will be carried out following processing currently underway.
Georeferenced photographic documentation is also reported.
