Correlazione tra sismicità ed elementi strutturali nell'isola d'Ischia

- Relationships between seismicity and tectonlc structures in the island of Ischia (Gu/f of Naples, Southern ltaly) - 11 Quaternario ltalian Journal of Quaternary Sciences, 9(1), 1996, 303-308 -An integrated study on historical seismicity and tectonic structures has made it possible to recognize the relationships between macroseismic data and strain field in the northern part of the island of Ischia (Gulf of Naples, Southern ltaly). Macroseismic maps based on new data and information from the literature suggest that the epicentral area was probably located in a restricted area that coincides with the northern bordar of Mt. Epomeo "horst''; this is the most conspicuous morphostructural feature of the island and is thought to control both seismic and tectonic activity in the island. lsoseismallines have a clear E-W trend; the maximum gradient is oriented N-Sand coincides with the least damaged areas. Kinematic analyses of the faults in the volcanic deposits of Casamicciola (a villaga on the nor.th of Mt. Epomeo), indicate a principal extension along the N to NNE direction in the oldest (>35 ka) tuffs; a secondary extension and transtension occur along a NNW direction and seem to affect also younger (10+2 ka) pumiceous formations. 8oth extensional episodes are localized on E-W to WNW-ESE trending structures. Major dip-slip displacements present along the Mt. Epomeo bordar faults are markedly attenuated to the east, where younger volcanic edifices (<10 ka) seem to seal most of the deformation structures. This situation conforms to the geometry of isoseismallines and sug­ gests a possible genetica! link between macroseismic and local strain fields, in turn controlled by the ragionai strain field of Southern ltaly.