GNGTS 2017 - 36° Convegno Nazionale

GNGTS 2017 S essione 1.1 63 References Boncio P., Galli P., Naso G. and Pizzi A., 2012; Zoning Surface Rupture Hazard along Normal Faults: Insight from the 2009 Mw 6.3 L’Aquila, Central Italy, Earthquake and Other Global Earthquakes . Bulletin of the Seismological Society of America, 102, 918–935, doi: 10.1785/0120100301. Livio F., Serva L. and Gurpinar A., 2016; Locating distributed faulting: Contributions from InSAR imaging to Probabilistic Fault Displacement Hazard Analysis (PFDHA). Quaternary International, 451/7, 223-233, 10.1016/ j.quaint.2016.09.034. Petersen M., Dawson T.E., Chen R., Cao T., Wills C.J., Schwartz, D.P., and Frankel A.D., 2011; Fault displacement hazard for strike-slip faults . Bull. Seismol. Soc. Am, 101 (2), 805–825. Youngs R. R., Arabasz W. J., Anderson R. E., Ramelli A. R., Ake J. P., Slemmons D. B., McCalpin J. P., Doser D. I., Fridrich C. J., Swan III F. H., Rogers A. M., Yount J. C., Anderson L. W., Smith K. D., Bruhn R. L., Knuepfer P. L. K., Smith R. B., dePolo C. M.,.O’Leary D. W, Coppersmith K. J., Pezzopane S. K., Schwartz D. P., Whitney J. W., Olig S. S., and Toro G. R., 2003; A methodology for probabilistic fault displacement hazard analysis (PFDHA) . Earthq. Spectra, 19, 191–219. Wells D. and Coppersmith K., 1994; New empirical relationships among magnitude, rupture length, rupture width, rupture area, and surface displacement . Bull. Seismol. Soc. Am., 84 (4), 974-1002. Zhou Q., Xu X., Yu G., Chen X., He H. and Yin G., 2010; Width Distribution of the Surface Ruptures Associated with the Wenchuan Earthquake: Implication for the Setback Zone of the Seismogenic Faults in Post-earthquake Reconstruction . Bull. Seismol. Soc. Am., 100, 5B, 2660-2668. THE INFLUENCE OF FAULTING STYLE AND TECTONIC REGIME ON THE FREQUENCY-MAGNITUDE DISTRIBUTION: A GLOBAL SURVEY A. Petruccelli 1 , D. Schorlemmer 2 , T. Tormann 3 , A.P. Rinaldi 3 , S. Wiemer 3 , P. Gasperini 1 , G. Vannucci 4 1 Department of Physics and Astronomy, University of Bologna, Italy 2 Helmholtz Centre GFZ, Potsdam, Germany 3 Swiss Seismological Service, ETH Zurich, Switzerland 4 Istituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy One of the ongoing debates in seismological research concerns the understanding of the frequency-magnitude distribution (FMD) of earthquakes, its potential variations on different scales, and its significance and interpretation. The large amount of publications on FMD reflects the importance of a proper understanding: observed spatial and temporal variations in Gutenberg and Richter (1944) GR relation b -value are often interpreted in a seismotectonic context, unraveling a wide range of processes that take place in the Earth’s crust. In fact, evidences from natural seismicity and laboratory measurements suggest an inverse relation between b -values and differential stress (Amitrano, 2003; Scholz, 1968, 2015): on local to regional scale, portions of highly stresses crust, like asperity structures, should result in lowering of b -value, indicating potential future rupture patches, while low stress zones should result in increasing of b -value. We want to propose a global synoptic picture of earthquakes frequency-magnitude distribution dependence on different tectonic regimes through a map of the GR relation b - value. Spatial patterns of b -values (higher for extensive and normal faulting regimes, lower for compressive-to-thrust faulting regimes and intermediate for heterogeneous zones) highlight the main global seismotectonic structures (oceanic ridges, subduction zones and continents). Moreover, our global b -value data independently distinguishes between previously established (Uyeda, 1982) types of subduction zones: a young, hot, slow-moving, low dipping angle, high buoyant slab (Chilean-type) produces high normal and shear stresses on the plate interface (low b -value), whereas an old, cold, fast-moving, high dipping and heavy slab (Mariana-type) produces lower stresses (high b -value). Differences in b -value for different tectonic styles are in line withAnderson (1905) theory of faulting: thrust faults are under higher stress with respect to normal faults, with strike-slip lying in