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Understanding rainfall-landslide relationships in man-modified environments: a case-history from Caramanico Terme, Italy 总被引：2，自引：0，他引：2
J. Wasowski 《Environmental Geology》1998,35(2-3):197-209
The expansion of Caramanico Terme in this century has led to the urbanization of marginally stable valley slopes, and this
has coincided with the apparent acceleration of landslide processes. Recent landslides on man-modified slopes were caused,
but not necessarily triggered, by heavy precipitation (antecedent moisture was a more critical factor than the amount of storm
rainfall). Because no important landslides on natural slopes in the same period were reported in the Caramanico area, a clear
distinction must be made between natural settings and those modified by man when determining rainfall thresholds for predictive
purposes. In recently urbanized mountainous environments, the thresholds used to assess landslide hazards should not be weighted
too heavily on old historical records of precipitation and associated mass movements. Instead, more weight ought to be given
to the period following the occurrence of any major anthropogenic and natural (e.g. high-magnitude earthquake) modification
of slope setting.
Received: 19 October 1996 · Accepted: 25 June 1997 相似文献
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Time probabilistic evaluation of seismically induced landslide hazard in Irpinia (Southern Italy) 总被引：2，自引：0，他引：2
A recently proposed method, which incorporates the Newmark model to evaluate the earthquake-induced landslide hazard at regional scale, was applied to Irpinia, one of the most seismically active regions of Italy. The method adopts a probabilistic approach to calculate values of critical acceleration ac representing the minimum strength required for a slope not to fail at a fixed probability level in a given time interval. Regional probabilistic hazard maps were generated for the two failure types most common in Irpinia (slump–earthflows and rock falls). The results suggest that quite moderate critical acceleration (0.05–0.08 g) could suffice to keep the slope failure probability low. However, the available data indicate that potential slide surfaces with ac below these values could be common in Irpinia, where, perhaps in relation to particular geo-environmental conditions, a relative large number of marginally stable slopes might survive other destabilising actions and fail even on occasion of not particularly strong earthquake shaking. 相似文献
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Factors Controlling Seismic Susceptibility of the Sele Valley Slopes: The Case of the 1980 Irpinia Earthquake Re-Examined 总被引：3，自引：0，他引：3
Janusz Wasowski Vincenzo Pierri Pierpaolo Pierri Domenico Capolongo 《Surveys in Geophysics》2002,23(6):563-593
Most of the documented slope failures triggered by the 1980 Irpinia earthquake (Ms 6.9) occurred in the upper Sele valley epicentral area (southern Italy). The early investigations revealed some puzzling characteristics of the slope failure distribution, i.e., (i) the higher landslide concentration on the valley slopes located farther away from the earthquake fault; (ii) the predominance of re-activations over first-time movements. The analyses of factors controlling the landslide concentrations indicates that the differences in hydrological setting and in slope were the two main causal factors whereas the seismic shaking, according to the radiation pattern modelling, could have been characterised by a relatively low rate of decrease across the valley. The aspect of the slopes did not play a significant role. The differences in groundwater conditions between the western and eastern valley sides were probably enhanced by the earthquake. In addition to the probable pore-water pressure rise, the seismic shaking caused large increases in the flow of springs draining the western aquifer, and this made the adjacent flysch slopes more prone to landsliding. Data from the available literature suggest that the effects of earthquake-induced groundwater release on seismic landslide distribution is especially important for normal-fault events. The Sele valley case also indicates that the slope of the pre-existing landslides is an important factor controlling their susceptibility to seismic re-activations. 相似文献
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Na+-humates obtained from humic acid before and after extraction with ethanol possess similar rather moderate surface activities, which do not vary with the ionic strength of the solution. The cross-sectional area of their surface-active molecule has been calculated 相似文献
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Investigating landslides with space-borne Synthetic Aperture Radar (SAR) interferometry 总被引：7，自引：0，他引：7
This paper is addressed to readers without advanced knowledge of remote sensing. It illustrates some current and potential uses of satellite Synthetic Aperture Radar interferometry (InSAR) for landslide assessment. Data acquired by SAR systems can provide 3D terrain models and be used to assist in regional scale investigations, e.g. aimed at evaluation of susceptibility of slopes to failure. Under favourable environmental conditions, the innovative Permanent Scatterers (PS) technique, which overcomes several limitations of conventional SAR differential interferometry (DInSAR) applications in landslide studies, is suitable for monitoring slope deformations with millimetric precision. The PS technique combines the wide-area coverage typical of satellite imagery with the capability of providing displacement data relative to individual image pixels. With the currently available radar satellites, however, only very slow ground surface displacements can be reliably detected and measured. The presented case study of a landslide from the Liechtenstein Alps indicates that the most attractive and reliable contribution provided by this remote sensing technique lies in the possibility of (i.) wide-area qualitative distinction between stable and unstable areas and (ii.) qualitative (relative) hazard zonation of large, slow landslides based on the identification of segments characterised by different movement rates. Since only the radar line of sight projection of the displacements can be detected, a quantitative exploitation of the PS data is possible only where sufficient ground truth is available. In site specific or single landslide investigations the PS data can represent a very useful complementary data source with respect to the information acquired through ground based observations and in situ surveying. However, the difficulties associated with the feasibility assessments of the applicability of SAR data to local scale problems, as well as with the interpretation of PS results, require a close collaboration between landslide experts and specialists in advanced processing of radar satellite data. The interpretation of the exact geotechnical significance of small, radar sensed ground surface deformations is challenging, especially where ground truth is lacking. Although any ground deformation is potentially of interest to an engineering geologist, detection of movements in both vertical and horizontal directions is needed in the case of landslides to evaluate slope failure mechanisms. With their high radar viewing angles, however, the current space-borne systems can detect only a fraction of the horizontal component of movement. It is expected that the upcoming SAR dedicated missions with new sensors and different acquisition geometries, combined with the rapid developments in the field of advanced radar data processing, will allow a full 3D reconstruction of deformation data and help to further reduce the current limitations of the PS and similar DInSAR approaches. 相似文献
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Landslide Activity Maps for Landslide Hazard Evaluation: Three Case Studies from Southern Italy 总被引：7，自引：0，他引：7
This paper focuses on the application of landslideactivity maps for evaluating the mass movementhazard in selected areas of the Southern Apenninesof Italy: Bisaccia, Calitri, and Buoninventre. Theavailability of multi-year aerial photo coveragehelped to assess the morphological changes whichoccurred in the last 40 years. This information,integrated with historical data on slope instabilityand field checks, were used to produce landslideactivity maps. These maps represent a short-cut inthe assessment of mass movement hazard, because theyfocus on the effects of slope instability ratherthan on the causative conditions and processes;however, if kept simple and prepared at large scale,they may help the local administrators and land-useplanners to reduce the socio-economic costs oflandslides. Furthermore, the comparative study oflandslide activity represents a relativelyinexpensive and quick method for evaluating theperformance of the engineering control efforts.The quantification of landslide activity in terms ofareal frequency can represent an additional step,useful to determine the relative landslide hazard(zonation in more or less hazardous areas). Forexample, the estimates of areal frequency of activelandsliding for the last 40 years demonstrated thegreat influence of the 1980 Irpinia earthquake(Ms = 6.9) on the stability of slopes situatedclose to its epicenter (within a radius of about20 km). 相似文献
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Mass movements and earthquakes represent two major geological hazards in the municipal territory of Caramanico Terme (south-central Apennines). Available records revealed the contemporaneous occurrence of earthquakes and slope failures on four occasions in the last four centuries (1627, 1706, 1933, and 1984). These events, with local intensities ranging from VI to IX, generated mass movements varying from a rotational slope failure to rock/block falls. All occurred in the southern periphery of the town and involved a thick carbonate megabreccia caprock and coarse colluvia which overlie a clayey substratum. Field investigation and review of historical records helped to delimit the areas susceptible to seismically triggered rockfalls. The mapping of historic and pre-historic rockfall deposits revealed their dispersal patterns and provided the basis for a determination of potential hazard zones. We approximate the temporal hazard assessment by relating the rockfall occurrence to the probability of earthquake triggering. Considering the VI degree triggering threshold indicated by local historical data, the statistical analysis of the regional seismic activity shows that events capable of inducing rockfalls have an approximately decennial recurrence in Caramanico. The approach presented could be readily applied to other potential risk areas of Italy by exploiting the rich long-term record of historical seismicity. In general, temporal hazard estimates at relatively low intensity levels will be possible even where the seismic history of the site is only well documented for a relatively limited time interval, provided that this interval is much longer than the recurrence time of the events exceeding the threshold considered. 相似文献
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V. Del Gaudio J. Wasowski P. Pierri U. Mascia G. Calcagnile 《Surveys in Geophysics》2000,21(4):391-406
Post-failure activity of the December 1993 Senerchia slump-earthflow was characterised by intermittent recession of the headscarp and earthflow movements. The retrogression showed considerable spatial variability, depending on the properties of the geological materials. The retrogressive failures were preceded by intense fissuring of the ground in the crown zone. Two microgravimetric surveys were carried out in order to detect possible spatial-temporal density variations in an area upslope of the headscarp. Although it was not possible to recognise any significant temporal density changes, this surveying revealed the presence of a negative anomaly which coincided with the area of maximum headscarp retreat. The gravity modelling was constrained by borehole information and new headscarp exposures produced by a series of retrogressive failures suggested that the origin of the anomaly might be associated with a hollow in an underlying clay-rich bedrock which had been subsequently filled by coarse colluvium. A possible concentration of groundwater in the hollow and its discharge towards the headscarp area controlled the local slope instability. The results of this study showed that microgravimetric surveys conducted upslope of retrogressive landslides can provide useful information on subsurface lithological heterogeneities that may control the amount and preferential direction of upslope landslide enlargement. 相似文献