Recent crustal deformations and tectonics of the Messina Strait area |
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| Authors: | F Mulargia P Baldi V Achilli F Broccio |
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| Institution: | Istituto Geofisico e Geodetico, Universitàdi Messina, Messina, Italy;Istituto di Geofisica, Universitàdi Bologna, Bologna, Italy;Istituto Nazionale di Geofisica, Rome, Italy;Istituto Geofisico e Geodetico, Universitàdi Messina, Messina, Italy |
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| Abstract: | Summary. The tectonics of the region at the convergence of the Tyrrhenian and Ionian basins is very complicated. The seismicity is particularly interesting in the area 38°–39° 30'N, 14° 30'–16° 30'E, where both deep events occur with compressive mechanism and crustal events with predominant normal faulting in excess of magnitude 7.0. The tectonic origin of this apparently contradictory behaviour can be traced to a remanent downgoing slab in the southern Tyrrhenian basin which is now inactive but is still undergoing considerable horizontal bending. Sedimentological studies suggest the bending to be accompanied by a marked uplift of Calabira reaching its highest rates in the area of the Strait of Messina. We performed a spirit levelling campaign in the Strait and found that a differential uplift of the inner lands with respect to coastlines took place in the period 1970–82. he question regarding the possibilities of either an absolute uplift of inner lands or a subsidence of coastlines can only be resolved after detailed tidal studies; the available tidal data seem to support the uplift hypothesis but they are substantially incomplete. The apparent pattern of vertical deformations seems to be a marked steady uplift with episodic subsidence periods in connection with large normal faulting earthquakes. Furthermore, our measurements and the results of a recently completed trilateration campaign tend to confirm the hypothesis of the existence of an angular graben in the Strait and a south–north right lateral slip of Sicily with respect to Calabria. |
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