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61.
62.
We investigate some statistical properties of the solar soft X-ray flux and of the Auroral Electrojet (AE) index. For both these signals, the probability density functions (PDFs) of normalized differences are shown to display wide, non-Gaussian tails. The shape of the PDFs is nearly unchanged as the timelag, used to calculate differences, varies. Moreover, the two time series are characterized by a power-law distribution for waiting times between successive bursts and by a clear departure from an hypothesis of locally Poisson statistics. A similar behavior is found in a shell model of magnetohydrodynamic (MHD) turbulence. 相似文献
63.
Mine subsidence damage from room and pillar mining in Illinois 总被引:1,自引:0,他引:1
Summary Data is presented on case histories of subsidence damage occurring over abandoned room and pillar mines in Illinois. The major modes of behaviour and damage in houses from sag-subsidence are described and summarized. The houses rested on crawl-space and basement foundations built from concrete and masonry. The prevalent mode of failure of bearing walls was inward bending. Failure is analysed and conventional design procedures are used to evaluate foundation failure. 相似文献
64.
Earthquake Damage Scenarios of the Building Stock of Potenza (Southern Italy) Including Site Effects 总被引:3,自引:0,他引:3
Mauro Dolce Angelo Masi Maria Marino Marco Vona 《Bulletin of Earthquake Engineering》2003,1(1):115-140
Damage scenarios relevant to the building stock of the town of Potenza, Southern Italy, are presented. A procedure for the
preparation of scenarios has been purposely set up. In the first step, the inventory of the building stock has been made.
Location and characteristics of buildings have been obtained from a survey carried out after the 1990 Potenza earthquake and
further updated in 1999. In the second step, the absolute vulnerability of the buildings has been evaluated. A hybrid technique
has been used, where typological analyses and expert judgement are combined together. Beyond the classes of vulnerability
A, B and C of the MSK scale, the class D of EMS98 scale, for the less vulnerable buildings, has been considered. The third
step has been the selection of the reference earthquakes by including also local amplification effects. Two events with 50
and 475 years return periods have been chosen as representative, respectively, of a damaging and of a destructive seismic
event expected in Potenza. The sites that may exhibit important amplification effects have been identified using the first
level method of the TC4 Manual. Damage scenarios of dwelling buildings have been prepared in the fourth step and reported
in a GIS. They are relevant to the selected reference earthquakes, taking into account or not site effects. The generally
low vulnerability of buildings results in a limited number of damaged buildings for the lower intensity earthquake, and of
collapsed buildings, for the higher intensity earthquake. The influence of site effects on the damage distribution is significant.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
65.
Marino Martini Luciano Giannini Antonella Buccianti Franco Prati Paola Cellini Legittimo Paolo Iozzelli Bruno Capaccioni 《Journal of Volcanology and Geothermal Research》1991,48(1-2)
A systematic geochemical investigation on the thermal manifestations of the volcanic area of Phlegrean Fields started in 1980, with the aim of obtaining useful information about the changes possibly occurring at the same time of vertical ground movements, termed as “bradyseismic”, which frequently interested this area.The attention was initially given to the fumaroles and the boiling pools of Solfatara and Pisciarelli, then subsequently extended to thermal springs, dug wells, and crater lakes.Analytical data pertaining to a period preceding the last crisis of 1982–1984 were then available, as well as other data collected during the previous crisis of 1970; a comprehensive picture of the variations observed before, during and after the acceleration of vertical movement has been drawn.According to the results obtained, the intrusion of a magmatic body as the trigger of the observed ground deformation is considered unrealistic. The whole area appears now in a quiet stage, and no further perturbation is expected without previous significant tectonic activity; chemical precursors appear suitable for an early detection of changes occurring at depth, to forecast possible consequences to be expected in the surface environment. 相似文献
66.
In order to investigate how the apparent separation of jointing varies according to the distance from faults, and how the mechanical properties of rock masses depend on this distance and jointing density, a number of regression analysis were performed on the variables s (apparent joint separation), d (distance from major fault), and sh (rebound value of Schmidt hammer).The variables were measured at 380 stations distributed over a wide study area located in the Aspromonte range in Calabria, Southern Italy.The most significant results of simple regression analysis are expressed by the formulas:
s=c+Fd05