The Santa Maria di Licodia earthquake of May 14, 1898

The earthquake of S.M. di Licodia is a typical shock of the Etnean area, characterized by a strong intensity concentrated in a very narrow area. The shock took place in an historical period quite favourable for seismological studies on Mount Etna. In particular, the instrumental surveillance of the volcano and macroseismic surveies of areas affected by earthquake, were usually carried out by volcanologists of that period. Thus it has been possible to find out very detailed information gathered with scientific purposes by contemporary volcanologists studying the geodynamic phenomena of the volcano (Ricco, Arcidiacono). The quality of descriptions allows better detail in the interpretation of intensity values compared to that which would be possible considering only the descriptions given by Baratta, who in this case is a contemporary author as well. Especially good accuracy in the determination of the mesoseismal area was obtained. The earthquake took place at 4.46 (G.M.T.) on May 14,1898 Mt. Etna was in a relatively quiet period since the end of the eruption of 1892 and only little shocks of modest magnitude occurred in that period, mostly in the eastern flank of the volcano (2). The studied earthquake, instead, involved the south-western part of Mount Etna, the villages of S.M. di Licodia, Ragalna, Biancavilla and Paterno, which were heavily struck and several houses damaged. In particular, S.M. di Licodia and the countryside Sparadrappo suffered heavy damage, though there were no victims. In the former village, twenty houses were destroyed and the rest of the houses were more or less damaged. The shock was also felt without heavy damage in several Etnean villages located mainly on the southern flank of the volcano, while in the north and in the eastern part of Mt. Etna the intensity of the shock was rather reduced. In Mascali and Giarre, located about 30 km away from the epicentral area, the shock seems to have not been felt at all (1). The area where the shock was felt was greatly expanded to the south, and the majority of the inhabitants of Mineo and Augusta, villages located in the northernmost part of hyblaean foreland, felt the earthquake as a strong shock (3). Moreover, it seems that aftershocks took place in the same area at 6.3 (G.M.T.) of the same day and the 22nd of the same month. The good quality of information gathered allowed the drawing of a isoseismal map (see figure), in which localities where the shock was not felt are indicated as well. The earthquake attained intensity VIII in the epicentral area. The mesoseismal area stretched in a NE-SW direction according to the trend of the tectonic structures existing in the area. The mesoseismal area is very narrow (7 km2) which indicates the shallowness of the event whose focal depth, macroseismically calculated, is about 6 km. The trend of isoseismals of lower degrees brings into evidence the sharp intensity decrease mainly towards the east and west from the epicentral area, while in the north-south direction the effects of the shock are distributed in a wider area. It is remarkable to note that effects of intensity IV are detectable towards the south till Mineo and Augusta. This further confirms the great energy propagation in the hyblaean foreland, as already observed for other shocks of northern Sicily and southern Calabria.