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691.
A critical relation for mobilization (failure) of an inclined, uniform soil layer is developed, based on the requirement for
balancing the driving stress and the resistance stress acting on the soil layer. Taking into consideration of the uncertainties
of parameters of the considered soil layer, the equation of the failure probability (Eq. 18) and the equation of the critical slope at various probabilities of failure (Eq. 22) for the soil layer by applying the first-order second-moment method (FOSM) were developed. The failure probabilities at
various mean relative water depths subject to the upper and lower values of the coefficients of variations of parameters and
two inclined angles of the soil layers are also estimated by using the Monte Carlo simulation method (MCSM) as well as by
using FOSM for comparisons. The results obtained by FOSM are in good agreement with that obtained by MCSM, but the former
is more efficient. Given the mean values and the coefficients of variation of related parameters of the soil layer, one can
easily estimate the failure probability and the critical failure slope of the soil layer by applying the equations or graphs
developed in the present study. 相似文献
692.
Floods and associated landslides account for the largest number of natural disasters and affect more people than any other
type of natural disaster. With the availability of satellite rainfall analyses at fine time and space resolution, it has also
become possible to mitigate such hazards on a near-global basis. In this article, a framework to detect floods and landslides
related to heavy rain events in near-real-time is proposed. Key components of the framework are: a fine resolution precipitation
acquisition system; a comprehensive land surface database; a hydrological modeling component; and landslide and debris flow
model components. A key precipitation input dataset for the integrated applications is the NASA TRMM-based multi-satellite
precipitation estimates. This dataset provides near real-time precipitation at a spatial-temporal resolution of 3 h and 0.25° × 0.25°.
In combination with global land surface datasets it is now possible to expand regional hazard modeling components into a global
identification/monitoring system for flood/landslide disaster preparedness and mitigation. 相似文献
693.
Trends in landslide occurrence in Nepal 总被引:2,自引:0,他引:2
David N. Petley Gareth J. Hearn Andrew Hart Nicholas J. Rosser Stuart A. Dunning Katie Oven Wishart A. Mitchell 《Natural Hazards》2007,43(1):23-44
Nepal is a mountainous, less developed kingdom that straddles the boundary between the Indian and Himalayan tectonic plates.
In Nepal, landslides represent a major constraint on development, causing high levels of economic loss and substantial numbers
of fatalities each year. There is a general consensus that the impacts of landslides in countries such as Nepal are increasing
with time, but until now there has been little or no quantitative data to support this view, or to explain the causes of the
increases. In this paper, a database of landslide fatalities in Nepal has been compiled and analysed for the period 1978–2005.
The database suggests that there is a high level of variability in the occurrence of landslides from year to year, but that
the overall trend is upward. Analyses of the trends in the data suggest that there is a cyclicity in the occurrence of landslide
fatalities that strongly mirrors the cyclicity observed in the SW (summer) monsoon in South Asia. Perhaps surprisingly the
relationship is inverse, but this is explained through an inverse relationship between monsoon strength and the amount of
precipitation in the Hill District areas of Nepal. It is also clear that in recent years the number of fatalities has increased
dramatically over and above the effects of the monsoon cycle. Three explanations are explored for this: land-use change, the
effects of the ongoing civil war in Nepal, and road building. It is concluded that a major component of the generally upward
trend in landslide impact probably results from the rural road-building programme, and its attendant changes to physical and
natural systems. 相似文献
694.
Cheng Qiu Tetsuro Esaki Mowen Xie Yasuhiro Mitani Chunxiang Wang 《Environmental Geology》2007,52(8):1569-1579
A shallow landslide triggered by rainfall can be forecast in real-time by modeling the relationship between rainfall infiltration
and decrease of slope stability. This paper describes a promising approach that combines an improved three-dimensional slope
stability model with an approximate method based on the Green and Ampt model, to estimate the time–space distribution of shallow
landslide hazards. Once a forecast of rainfall intensity and slope stability-related data, e.g., terrain and geology data,
are acquired, this approach is shown to have the ability to estimate the variation of slope stability of a wide natural area
during rainfall and to identify the location of potential failure surfaces. The effectiveness of the estimation procedures
described has been tested by comparison with a one-dimensional method and by application to a landslide-prone area in Japan. 相似文献
695.
Generation of a landslide risk index map for Cuba using spatial multi-criteria evaluation 总被引:5,自引:2,他引:5
This paper explains the procedure for the generation of a landslide risk index map at national level in Cuba, using a semi-quantitative
model with ten indicator maps and a cell size of 90 × 90 m. The model was designed and implemented using spatial multi-criteria
evaluation techniques in a GIS system. Each indicator was processed, analysed and standardised according to its contribution
to hazard and vulnerability. The indicators were weighted using direct, pairwise comparison and rank-ordering weighting methods,
and weights were combined to obtain the final landslide risk index map. The results were analysed per physiographic region
and administrative units at provincial and municipal levels. The Sierra Maestra mountain system was found to have the largest
concentration of high landslide risk index values while the Nipe–Cristal–Baracoa system has the highest absolute values, although
they are more dispersed. The results obtained allow designing an appropriated landslide risk mitigation plan at national level
and to link the information to the national hurricane early warning system, allowing also warning and evacuation for landslide-prone
areas. 相似文献
696.
A new hazard zonation methodology is applied to the East Coast Bays area of North Shore City, one of the most residentially
developed cliffed shorelines in New Zealand. It is based on a series of geotechnical cliff profiles from three pilot study
areas (George Gair Lookout, Rahopara Reserve–Kennedy Memorial Park, and Mairangi Bay–Rothesay Bay) which detail many of the
variables that influence overall cliff stability.
The methodology requires calculation of a Coastal Landslide Hazard Zone (CLHZ) width for each geotechnical profile and is
derived by quantifying three factors: the rate of long-term sea-cliff retreat; the amount of horizontal retreat expected from
either joint block fall, fault plane failure, or bedding plane failure, coupled with the amount of horizontal retreat resulting
from slumping of the top weathered layer; and a safety factor. The rate of long-term sea-cliff retreat is multiplied by a
hazard assessment period of 100 years, which is then added with the two other factors to derive a CLHZ width. Finally, the
widths are entered into a Geographic Information System (GIS) to delineate a hazard zone.
Owing to the very low rates (< 0.1 m a−1) of sea-cliff retreat in the East Coast Bays area, the long-term rate of sea-cliff retreat at each profile location could
not be quantified by conventional survey techniques. Instead, a Sea-cliff Vulnerability Index (SVI) was employed to quantify
the long-term rate. Weighted variables considered in the SVI include the bedding dip direction, the occurrence of faults and
their orientation, sea-cliff aspect, cliff-toe and cliff-face lithology, cliff-top height, and the presence of groundwater
seepage.
Calculated CLHZ widths along East Coast Bays range between 13 m and 34 m inland of a reference cliff-line in response to spatial
variations of the sea-cliff geology and morphology. The widths reflect the estimated degree of risk over the next 100 years
from coastal erosion and landslips. 相似文献
697.
The Yudonghe landslide is located in a upcoming reservoir region of a 233-m-high Shuibuya rockfill dam, 2,300 m away from
the dam site. It consists of a massive landslide with upper and lower segments and two secondary slides, i.e. an eastern secondary
slide and a western secondary slide. In this paper, values of factor of safety (FS) for various masses were calculated in
a scenario of reservoir impounding-induced increase in groundwater levels, using a method of three-dimensional (3D) limit
equilibrium. Results showed that the smallest value of FS for the massive landslide is 1.12 computed on the presupposition
of reactivating along a bottom slide zone in case of an earthquake. The smallest FS value of the lower slide mass is 1.12
in a possible direction, given earthquake occurrence and a groundwater level of 225 m above the sea level. This FS value shows
that the lower slide mass is stable in case of groundwater increasing. In addition, by the calculation of the 3D limit equilibrium
method, the FS value of the east secondary slide is approximately 1.0 in different groundwater levels under consideration
of earthquake occurrence, which reflects that this mass is prone to reactivate when external factors are taken into effect. 相似文献
698.
Paula K. Dunbar 《Natural Hazards》2007,42(3):529-536
NOAA’s National Geophysical Data Center is using state-of-the-art Internet tools for natural hazards education, public outreach,
and access to natural hazards data. For example, NGDC acquires, processes, and provides access to geologic hazards event data
that are useful in natural hazards risk assessment and hazards-related research. In addition, a collection of natural hazards
slides and a teacher’s guide on volcanoes are available online. NGDC also created an online “Kids Hazards Quiz” to test the
user’s knowledge of disaster safety information. An online Natural Hazards Data Resources Directory provides access to information
and links to organizations that provide natural hazards data and information. Expanded access to these data and information
by the public and researchers can increase public awareness of natural hazards, improve hazards research, and ultimately reduce
the devastating impacts of natural disasters. 相似文献
699.
The present study investigates the factors associated with the occurrence of landslides along with the National Highway (NH
39) connecting Assam-Manipur (India) to Myanmar. Kinematics and slope stability analyses were used to gain an understanding
of the causes of slope failure despite the terrain comprising material with a high safety factor. The study area falls within
a high seismic zone along the regional Churachandpur-Mao Thrust (CMT) situated west of the Indo-Myanmar subduction zone. Based
on these studies of seismicity, slip rates, creeping, among others, it was inferred that CMT is a creeping regional fault
running parallel to the subduction zone boundary creeping segment of CMT and that the CMT requires further monitoring to assess
the landslide hazard in the region. 相似文献
700.