A schematic subdivision of the Hyblean foreland, based un structural fcatures and the tectonic sedimentary evolution of tbe Upper Miocene Quaternary intcrval, is prescntcd. The foreland is formed by a horst with NE-SW alignment (Altipiano calcareo s.s.). It is bounded south-eastwards by the Depressione di Ispica-Capo Passero (Ispica-Capo Passero depression) and northwestwards by a (Zona di transizione (transition zone) passing to the «Avanfossa Gela-Catania» (GelaCatania forcdeep). In detail, the ({Settore Ionico» (Ionian sector) is considered separately from the l'est of the "Altipiano calcareo», because an originai common tectonic-sedimentary evolution became distinctly separate after the Upper Miocene. The evolution of the Ionian Sector is probably linked to the Hyblean Maltese Escarpment a NNW-SSE fault system affecting the Ionian border or Sicily. Outcrops along the NW margin all the foreland are truncated by the NESW system, which carries tbe «transition zone», below the nappes of the Northern Chain. Within the NW margin of the Hyblean Plateau it is postulated that the tensional phenomena are the shallow effect of a general cumpressive regime. In contrast, thc eastern bordcr (" Ionian ScctoP» is interpreted as a sector with continental collapsed crl1st. Also the location of epicentres in SE Sicily points aut the existence of two main scctors. The western sector displays a great number of events with small intensity; the eastern sector is characterized by a modest number of earthquakes which have a very high intensity. These variations indicate two different kinds of encrgy release. Geo-structural evidencc and the distribution of hypocentres or the two sectors showing different seismotectonic styles further strengthen thc subdivision. The western sector is charactcrized by superficial crustal seismicity linked to tensional structures reprcsenting the shallow seismic cffeets of an overall compressive field. The Ionian sector exhibits deeper earthquakes; these are located close to the coast line and are probably related to the tensional structures connected with the Malta-Hyblean Escarpment.
Elementi per una prima valutazione dei caratteri sismotettonici dell'avampaese ibleo (Sicilia sud - orientale)
CARBONE, Serafina;LOMBARDO, Giuseppe;
1982-01-01
Abstract
A schematic subdivision of the Hyblean foreland, based un structural fcatures and the tectonic sedimentary evolution of tbe Upper Miocene Quaternary intcrval, is prescntcd. The foreland is formed by a horst with NE-SW alignment (Altipiano calcareo s.s.). It is bounded south-eastwards by the Depressione di Ispica-Capo Passero (Ispica-Capo Passero depression) and northwestwards by a (Zona di transizione (transition zone) passing to the «Avanfossa Gela-Catania» (GelaCatania forcdeep). In detail, the ({Settore Ionico» (Ionian sector) is considered separately from the l'est of the "Altipiano calcareo», because an originai common tectonic-sedimentary evolution became distinctly separate after the Upper Miocene. The evolution of the Ionian Sector is probably linked to the Hyblean Maltese Escarpment a NNW-SSE fault system affecting the Ionian border or Sicily. Outcrops along the NW margin all the foreland are truncated by the NESW system, which carries tbe «transition zone», below the nappes of the Northern Chain. Within the NW margin of the Hyblean Plateau it is postulated that the tensional phenomena are the shallow effect of a general cumpressive regime. In contrast, thc eastern bordcr (" Ionian ScctoP» is interpreted as a sector with continental collapsed crl1st. Also the location of epicentres in SE Sicily points aut the existence of two main scctors. The western sector displays a great number of events with small intensity; the eastern sector is characterized by a modest number of earthquakes which have a very high intensity. These variations indicate two different kinds of encrgy release. Geo-structural evidencc and the distribution of hypocentres or the two sectors showing different seismotectonic styles further strengthen thc subdivision. The western sector is charactcrized by superficial crustal seismicity linked to tensional structures reprcsenting the shallow seismic cffeets of an overall compressive field. The Ionian sector exhibits deeper earthquakes; these are located close to the coast line and are probably related to the tensional structures connected with the Malta-Hyblean Escarpment.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
