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On 21 August 2017 at 20:57 (local time) a very shallow (H = 1.2 km), moderate (Md = 4.0), earthquake hit the volcanic island of Ischia (Southern Italy), causing the death of two people. The study of the damage to the buildings with the European Macroseismic Scale 98 (EMS-98), carried out immediately after the earthquake, highlighted that hilly area of Casamicciola Terme, on the northern side of the Mt. Epomeo, was the most damaged part of the island with locally quite relevant damage (I = VIII EMS). This seismic event is the first damaging earthquake in Ischia during the instrumental era. In fact, this provides, for the first time, the opportunity to integrate historical seismicity, macroseismic observations, instrumental information, and detailed mapping of the geological coseismic effects. In this work we evaluate the effects induced by the 2017 Casamicciola earthquake on the environment using the Environmental Seismic Intensity 2007 (ESI-07) macroseismic scale. This macroseismic analysis, together with the superficial coseismic faulting characteristics and the available geophysical information, allows us to reconsider the source model for the 2017 earthquake and the previous damaging historical earthquakes in the Casamicciola Terme area. The application of the ESI scale to the Casamicciola Terme earthquake of 21 August 2017 and the assignment of seismic intensity offers better spatial resolution, as well as an increase of the time window for the assessment of the seismic hazard, allowing to reduce the implicit uncertainty in the intensity attenuation laws in this peculiar volcano-tectonic setting. Since intensity is linked to the direct measure of damage, and it is commonly used in hazard assessment, we argue that building damage at Casamicciola Terme is strongly influenced by earthquake surface faulting and near field effects, and therefore controlled by the geometry of the seismic source.

The aim of this study is a critical revision of historical and recent seismicity of the Salento peninsula (Apulia, Southern Italy), offering an updated evaluation of its seismic hazard currently underestimated. This area is actually included in the least dangerous IV category of the Italian seismic classification. The Salento Peninsula was struck by the February 20, 1743 earthquake, considered as the strongest seismic event of this area. The reassessment of both the macroseismic effects on man-made structures, and the triggered effects in the natural environment has been carried out on the basis of archival documents and recent literature, according to the MCS and the ESI 2007 scale. The main result of our study has been the re-evaluation of the maximum intensity (Imax=XMCS) of the 1743 earthquake, besides new intensity values for some localities along the Apulian coasts.

EARTHQUAKE ENVIRONMENTAL EFFECTS, INTENSITY AND SEISMIC HAZARD ASSESSMENT: THE EEE CATALOGUE (INQUA PROJECT #0418)

The traditional approach for seismic intensity assessment based mostly on effects on humans and manmade structures often results poorly constrained, especially in the epicentral area of strong-to-large earthquakes (intensity degree >IX) when the intensity scales are afflicted by saturation, and in sparsely populated areas. The application of the recent ESI intensity scale, which uses characteristics and distribution of earthquake environmental effects to evaluate seismic intensity, has confirmed that this approach provides more complete and reliable images of earthquakes, being its environmental effects more closely related to the earthquake size. Remote sensing techniques (multispectral images, hi-res DEMs from IFSAR and LIDAR data, D-InSAR and PS-InSAR) play a crucial role in mapping earthquake environmental effects. Therefore, seismic intensity assessments based on environmental effects are expected to strongly benefit from the regular application of remote sensing techniques to recent earthquakes and, in perspective, to the earthquakes that will occur in the next future.