GNGTS 2017 - 36° Convegno Nazionale

GNGTS 2017 S essione 3.1 587 Daubechies I.; 1992: Ten Lectures on Wavelets . Society of Industrial and Applied Mathematics, 357 pp. DOI 10.1137/1.9781611970104 Deighan A. J. and Watts D.R.; 1997: Ground roll suppression using the wavelet transform . Geophysics, 62 , 1896– 1903. DOI 10.1190/1.1444290 Farge M.; 1992: Wavelet transforms and their applications to turbulence . Annual Review of Fluid Mechanics, 24 , 395-457. DOI 24.010192.002143 Lau K. M. and Weng H.; 1995: Climate signal detection using wavelet transform: how to make a time series sing . Bulletin of the American Meteorological Society, 76 , 2391-2402. Mallat S.; 2009: A Wavelet Tour of Signal Processing. 3rd ed, Academic Press Inc. Sadowsky J.; 1996: Investigation of signal characteristics using the continuous wavelet transforms. Johns Hopkins APL Technical Digest, 17 , 258–269. Sinha S., Routh R., Anno P. and Castagna J.; 2005: Spectral decomposition of seismic data with continuous-wavelet transform. Geophysics, 70 , 19–25. Tognarelli A. and Stucchi E.; 2016: S/N anhancement by means of array simulation for near surface seismic investigations . Near Surface Geophysics, 14 (3), 221-229. DOI 10.3997/1873-0604.2016013 Torrence C. and Compo G. P.; 1998: A practical guide to wavelet analysis . Bulletin of the American Meteorological Society, 79 , 61-78. STUDY OF THE SEISMICALLY CHAOTIC UNITS NORTH OF THE GORRINGE BANK (SW IBERIAN MARGIN, ATLANTIC OCEAN): IMPLICATIONS FOR COASTAL TSUNAMI HAZARD F. Turco 1 , J.C. Duarte 2 , U. Tinivella 3 , M. Giustiniani 3 , A. Del Ben 1 , P. Terrinha 4 1 Dip. Matematica e Geoscienze (DMG), University of Trieste, Italy 2 Instituto Dom Luiz - Faculdade de Ciências da Universidade de Lisboa, Lisbon, Portugal 3 Istituto Nazionale di Geofisica e Oceanografia Sperimentale - OGS, Sgonico (TS), Italy 4 Instituto Português do Mar e da Atmosfera (IPMA), Lisbon, Portugal Introduction. The Gulf of Cadiz, located at the African-Eurasian plate boundary, is a natural laboratory to study a broad spectrum of geological processes. Moderate to high magnitude earthquakes are frequent in this region. Moreover, the irregular seafloor morphology, characterized by huge seamounts, abyssal plains, steep slopes and submarine canyons, is a preconditioning factor for large submarine avalanches. Both earthquakes and landslides are potential triggering mechanisms for devastating tsunamis along the SW Iberian and NWAfrican coasts. Historically, these areas have suffered major earthquakes and tsunamis, such as the famous 1755 M W 8.7 Lisbon earthquake, one of the largest earthquake ever recorded in western Europe (Baptista et al. , 1998). The source of the 1755 earthquake is still matter of debate. In the SW Iberian margin, the plate boundary is diffuse, and deformation occurs along a 200 km wide band, in a transpressive regime (Zitellini et al. , 2009). The relative plate movement is accommodated by the recently discovered SWIM dextral strike – slip faults, and by a series of NE – SW trending thrusts that are often related to submarine anticlines and seamounts, such as the Gorringe Bank thrust (Fig. 1). The Gorringe Bank is a thrust – related anticline that elevates over 5000 m above the surrounding abyssal plains. The North Gorringe Chaotic Bodies are seismically chaotic units whose analysis is presented in this work; they were identified at the feet of the Gorringe Bank’s northern flank. Both accretionary prisms and landslides deposits are usually characterized by a seismically chaotic acoustic image caused by internal tectonic deformation in the first case, and by strong lithological and granulometrical heterogeneity, in the second case. The fact that the Gorringe Bank lies on the top of a regional thrust that has accommodated from 20 to 50 km of plate convergence between Africa and Eurasia since Early Cenozoic (Sartori et al. , 1994; Jimenez-Munt et al. , 2010) makes this area a favourable geological environment both for the