The Campi Flegrei caldera (Italy) has been the site of intense seismic activity over the past decades. This area is densely populated and includes important towns such as Napoli with historical sites and supporting many industries. For the proper use and management of the region, the evaluation of the dynamic properties of near-surface rocks is necessary.
The volcanological pattern has been reconstructed from the lithostratigraphies of several drillings. The most interesting and widespread pyroclastic products are the pozzolana deposit (soil) and the Neapolitan Yellow Tuff (rock). Both pozzolana and tuff products are covered by recent eluvial and coastal sandy deposits and younger volcanic products (<12 000 years). The characteristic ranges of the shear wave velocity (Vs) of the Campi Flegrei–Neapolitan soils and tuffs are defined and the primary influencing factors are evaluated. For the sandy deposits, the results show that eluvial and lacustral products have lower shear wave velocities than coastal products. For the volcanic products younger than 12 000 years b.p. the influence of vertical pressure is emphasized. As regards the pozzolana deposit (soil) and the Neapolitan Yellow Tuff (rock), a major influencing factor is shown by the textural characteristics and the different hardening degrees as a consequence of the diagenetic processes. The scattering of the Vs velocities for the same formation is so wide that only the variability ranges can be individuated. These results suggest a need to carry out detailed Vs measurements or, at least, to make a parametric study of the effect of the Vs ranges on seismic response analysis in order to give safe building codes. 相似文献
It is well accepted that the parent distribution for individual ocean wave heights follows the Weibull model. However this
model does not simulate significant wave height which is the average of the highest one-third of some ‘n’ (n- varies) wave heights in a wave record. It is now proposed to redefine significant wave height as average of the highest one-third
of a constant number (n-constant, say,n = 100) of consecutive individual wave heights. The Weibull model is suggested for simulating redefined significant wave height
distribution by the method of characteristic function. An empirical support of 100.00% is established by Χ2-test at 0.05 level of significance for 3 sets of data at 0900, 1200 and 1500 hrs at Valiathura, Kerala coast. Parametric
relations have been derived for the redefined significant wave height parameters such as mean, maximum one-third average,
extreme wave heights, return periods of an extreme wave height and the probability of realising an extreme wave height in
a time less than the designated return period. 相似文献