GNGTS 2014 - Atti del 33° Convegno Nazionale

Rovere M., Gamberi F., Mercorella A., Rashed H., Gallerani A., Leidi E., Marani M., Funari V. and Pini G.A.; 2014a. Venting and seepage systems associated with mud volcanoes and mud diapirs in the southern Tyrrhenian Sea . Mar. Geol., 347 , 153–171. Rovere M., Rashed H., Pecchioni E., Ceregato A. and Gamberi F.; 2014b: Normal faults control fluid flow structures and cold seep habitats at the rear of the Calabrian Arc (Paola Ridge, southeastern Tyrrhenian Sea) . Geophys. Res. Abstr., 16 , 24240. Rovere M., Rashed H., Pecchioni E., Mercorella A., Ceregato A., Leidi E., Gamberi F., and Vaselli O.; 2014: Habitat mapping of cold seeps associated with authigenic mineralization (Paola Ridge, southern Tyrrhenian Sea): combining seafloor backscatter with biogeochemistry signals . Italian Journal of Geosciences, in press. Schneider von Deimling J., Brockhoff J. and Greinert J.; 2007: Flare imaging with multibeam systems: Data processing for bubble detection at seeps . Geochemistry, Geophys. Geosystems, 8 , Q06004. Serié C., Huuse M. and Schodt N.H.; 2012: Gas hydrate pingoes: Deep seafloor evidence of focused fluid flow on continental margins . Geology, 40 , 207–210. Sultan N., Bohrmann G., Ruf ne L., Pape T., Riboulot V., Colliat J.-L., Prunelé, A. De, Dennielou, B., Garziglia S., Himmler T., Marsset T., Peters C.A., Rabiu A., Wei J.; 2014: Pockmark formation and evolution in deep water Nigeria: Rapid hydrate growth versus slow hydrate dissolution . J. Geophys. Res. Solid Earth, 119 , 2679–2694. Van Dijk J., Bello M., Brancaleoni G., Cantarella G., Costa V., Frixa A., Golfetto F., Merlini S., Riva M., Torricelli S., Toscano, C. and Zerilli A.; 2000: A regional structural model for the northern sector of the Calabrian Arc (southern Italy) . Tectonophysics, 324 , 267–320. Cause of East-West Earth Asymmetry G. Scalera Retired from INGV, Istituto Nazionale di Geofisica e Vulcanologia, Roma, Italy Introduction. Many efforts to explain some asymmetric characteristics of our globe and of the global tectonics have been made (Bostrom, 1971; Stevenson and Turner, 1977; Marotta and Mongelli, 1998; Doglioni et al. , 1999; Carminati and Doglioni, 2012) most of them using the implicit or explicit assumptions of plate tectonics geodynamics. A non exhaustive list of asymmetries of the Earth is: The magnetic polarity (Gilbert, 1600); The land-hemisphere and the water-hemisphere; southern tips of the continents (Bacon, 1620; Mantovani, 1909; Barnett, 1969; Carey, 1996; among others); Larger extension of expanding mid-oceanic ridges on the southern hemisphere. South-eastward trend of younger ages in the long Pacific seafloor volcanic chains; A larger width of the seafloor isochrones bands on the Nazca region; Apear-shaped Earth; etc. Many other additional asimmetries have been described [see for a review: Carey (1959, 1963)]. It is a few decades that the different slopes of the Wadati-Benioff zones oriented towards the east and west has been enclosed in the list of asymmetries of the Earth. Namely, the alleged subductions under the Americas have an angle of about 30°, while under the east Pacific coasts (Asia, Japan) the angle is steeper (Luyendyk, 1970; Isacks and Barazangi, 1977; Riguzzi et al. , 2010; and many others). The cause of this difference has been identified by main stream in the tidal drag that would cause a global shift of the lithosphere towards west (the so called “westward drift”). The Coriolis inertial effect. The unavoidable existence of the Coriolis fictitious force on a rotating Earth (Gerkema and Gostiaux, 2012; Gerkema et al. , 2008) has inspired several authors to search for the possible effects of this sollecitation on the surface observable tectonic features (Van Bemmelen, 1971; Rance, 1967; Howell, 1970; Kane, 1972; Hughes, 1973; Storetvedt, 1992; Pan,1993; Donescu and Munteanu, 2011). In the opposite party was Jeffreys (1928) and many others up to our days (Jordan, 1974; Ranalli, 2000; Ricard, 2007; Doglioni et al. , 2011), whose main argument is the extremely large viscosities of mantle, and the consequent assumption that the inertial terms in the Navier-Stokes equations are negligible. GNGTS 2014 S essione 1.2 175