Earth-printshttps://www.earth-prints.orgThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Sat, 24 Oct 2020 05:25:24 GMT2020-10-24T05:25:24Z5021The exploding-reflector concept for ground-penetrating-radar modelinghttp://hdl.handle.net/2122/724Title: The exploding-reflector concept for ground-penetrating-radar modeling
Authors: Carcione, J. M.; Feliciangeli, L. P.; Zamparo, M.
Abstract: The simulation of a stacked radargram requires the calculation of a set of common-source experiments and application of the standard processing sequence. To reduce computing time, a zero-offset stacked section can be obtained with a single simulation, by using the exploding-reflector concept and the so-called non-reflecting wave equation. This non-physical modification of the wave equation implies a constant impedance model to avoid multiple reflections, which are, in principle, absent from stacked sections and constitute unwanted artifacts in migration processes. Magnetic permeability is used as a free parameter to obtain a constant impedance model and avoid multiple reflections. The reflection strength is then implicit in the source strength. Moreover, the method generates normal-incidence reflections, i.e. those having identical downgoing and upgoing wave paths.Exploding reflector experiments provide correct travel times of diffraction and reflection events, in contrast to the plane-wave method.
Tue, 01 Jan 2002 00:00:00 GMThttp://hdl.handle.net/2122/7242002-01-01T00:00:00ZAssessing the completeness of Italian historical earthquake datahttp://hdl.handle.net/2122/789Title: Assessing the completeness of Italian historical earthquake data
Authors: Stucchi, M.; Albini, P.; Mirto, M.; Rebez, A.
Abstract: The assessment of the completeness of historical earthquake data (such as, for instance, parametric earthquake catalogues) has usually been approached in seismology - and mainly in Probabilistic Seismic Hazard Assessment(PSHA) - by means of statistical procedures. Such procedures look «inside» the data set under investigation and compare it to seismicity models, which often require more or less explicitly that seismicity is stationary. They usually end up determining times (Ti), from which on the data set is considered as complete above a given magnitude (Mi); the part of the data set before Ti is considered as incomplete and, for that reason, not suitable for statistical analysis. As a consequence, significant portions of historical data sets are not used for PSHA.
Dealing with historical data sets - which are incomplete by nature, although this does not mean that they are of low value - it seems more appropriate to estimate «how much incomplete» the data sets can be and to use them together with such estimates. In other words, it seems more appropriate to assess the completeness looking «outside
» the data sets; that is, investigating the way historical records have been produced, preserved and retrieved. This paper presents the results of investigation carried out in Italy, according to historical methods. First, the completeness of eighteen site seismic histories has been investigated; then, from those results, the completeness of areal portions of the catalogue has been assessed and compared with similar results obtained by statistical
methods. Finally, the impact of these results on PSHA is described.
Thu, 01 Jan 2004 00:00:00 GMThttp://hdl.handle.net/2122/7892004-01-01T00:00:00Z