排序方式： 共有18条查询结果，搜索用时 62 毫秒
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Reid Mark E. Godt Jonathan W. LaHusen Richard G. Slaughter Stephen L. Badger Thomas C. Collins Brian D. Schulz William H. Baum Rex L. Coe Jeffrey A. Harp Edwin L. Schmidt Kevin M. Iverson Richard M. Smith Joel B. Haugerud Ralph A. George David L. 《Landslides》2021,18(9):2993-3009
On 22 March 2014, a massive, catastrophic landslide occurred near Oso, Washington, USA, sweeping more than 1 km across the adjacent valley flats and killing 43 people. For the following 5 weeks, hundreds of workers engaged in an exhaustive search, rescue, and recovery effort directly in the landslide runout path. These workers could not avoid the risks posed by additional large-scale slope collapses. In an effort to ensure worker safety, multiple agencies cooperated to swiftly deploy a monitoring and alerting system consisting of sensors, automated data processing and web-based display, along with defined communication protocols and clear calls to action for emergency management and search personnel. Guided by the principle that an accelerating landslide poses a greater threat than a steadily moving or stationary mass, the system was designed to detect ground motion and vibration using complementary monitoring techniques. Near real-time information was provided by continuous GPS, seismometers/geophones, and extensometers. This information was augmented by repeat-assessment techniques such as terrestrial and aerial laser scanning and time-lapse photography. Fortunately, no major additional landsliding occurred. However, we did detect small headscarp failures as well as slow movement of the remaining landslide mass with the monitoring system. This was an exceptional response situation and the lessons learned are applicable to other landslide disaster crises. They underscore the need for cogent landslide expertise and ready-to-deploy monitoring equipment, the value of using redundant monitoring techniques with distinct goals, the benefit of clearly defined communication protocols, and the importance of continued research into forecasting landslide behavior to allow timely warning.
相似文献3.
J.F. Harp 《Journal of Hydrology》1974,21(1):27-31
This brief paper presents an extension of the moving boat method whereby intermediate sized streams may be gaged automatically, by means of a moving meter, by remote control with no operator at the point of the velocity measurement. The paper is clearly innovative in that no velocity magnitude measurement is required, only an angle measurement and a known input constant velocity of traversing meter. The technique presented here is most unusual in that a new technique is combined with classical methodology to produce a reliable field measurement of streamflow rates in a remarkably short time. 相似文献
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Progressive rock‐fall failures in natural rock slopes are common in many environments, but often elude detailed quantitative documentation and analysis. Here we present high‐resolution photography, video, and laser scanning data that document spatial and temporal patterns of a 15‐month‐long sequence of at least 14 rock falls from the Rhombus Wall, a sheeted granitic cliff in Yosemite Valley, California. The rock‐fall sequence began on 26 August 2009 with a small failure at the tip of an overhanging rock slab. Several hours later, a series of five rock falls totaling 736 m3 progressed upward along a sheeting joint behind the overhanging slab. Over the next 3 weeks, audible cracking occurred on the Rhombus Wall, suggesting crack propagation, while visual monitoring revealed opening of a sheeting joint adjacent to the previous failure surface. On 14 September 2009 a 110 m3 slab detached along this sheeting joint. Additional rock falls between 30 August and 20 November 2010, totaling 187 m3, radiated outward from the initial failure area along cliff (sub)parallel sheeting joints. We suggest that these progressive failures might have been related to stress redistributions accompanying propagation of sheeting joints behind the cliff face. Mechanical analyses indicate that tensile stresses should occur perpendicular to the cliff face and open sheeting joints, and that sheeting joints should propagate parallel to a cliff face from areas of stress concentrations. The analyses also account for how sheeting joints can propagate to lengths many times greater than their depths behind cliff faces. We posit that as a region of failure spreads across a cliff face, stress concentrations along its margin will spread with it, promoting further crack propagation and rock falls. Published in 2012. This article is a US Government work and is in the public domain in the USA. 相似文献
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Dylan R. Harp Velimir V. Vesselinov 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(7):1023-1042
An approach is presented for identifying statistical characteristics of stratigraphies from borehole and hydraulic data. The
approach employs a Markov-chain based geostatistical framework in a stochastic inversion. Borehole data provide information
on the stratigraphy while pressure and flux data provide information on the hydraulic performance of the medium. The use of
Markov-chain geostatistics as opposed to covariance-based geostatistics can provide a more easily interpreted model geologically
and geometrically. The approach hinges on the use of mean facies lengths (negative inverse auto-transition rates) and mean
transition lengths (inverse cross-transition rates) as adjustable parameters in the stochastic inversion. Along with an unconstrained
Markov-chain model, simplifying constraints to the Markov-chain model, including (1) proportionally-random and (2) symmetric
spatial correlations, are evaluated in the stochastic inversion. Sensitivity analyses indicate that the simplifying constraints
can facilitate the inversion at the cost of spatial correlation model generality. Inverse analyses demonstrate the feasibility
of this approach, indicating that despite some low parameter sensitivities, all adjustable parameters do converge for a sufficient
number of ensemble realizations towards their “true” values. This paper extends the approach presented in Harp et al. (doi:, 2008) to (1) statistically characterize the hydraulic response of a geostatistical model, thereby incorporating an uncertainty
analysis directly in the inverse method, (2) demonstrate that a gradient-based optimization strategy is sufficient, thereby
providing relative computational efficiency compared to global optimization strategies, (3) demonstrate that the approach
can be extended to a 3-D analysis, and (4) introduce the use of mean facies lengths and mean transition lengths as adjustable
parameters in a geostatistical inversion, thereby allowing the approach to be extended to greater than two category Markov-chain
models. 相似文献
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Dylan R. Harp Velimir V. Vesselinov 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(1):159-168
Decision making under severe lack of information is a ubiquitous situation in nearly every applied field of engineering, policy, and science. A severe lack of information precludes our ability to determine a frequency of occurrence of events or conditions that impact the decision; therefore, decision uncertainties due to a severe lack of information cannot be characterized probabilistically. To circumvent this problem, information gap (info-gap) theory has been developed to explicitly recognize and quantify the implications of a severe lack of information in decision making. This paper presents a decision analysis based on info-gap theory developed for a contaminant remediation scenario. The analysis provides decision support in determining the fraction of contaminant mass to remove from the environment. An info-gap uncertainty model is developed to characterize uncertainty due to a lack of information concerning the contaminant flux. The info-gap uncertainty model groups nested, convex sets of functions defining contaminant flux over time based on their level of deviation from a nominal contaminant flux. The nominal contaminant flux defines a best estimate of contaminant flux over time based on existing, though incomplete, information. A robustness function is derived to quantify the maximum level of deviation from nominal that still ensures compliance for alternative decisions. An opportuneness function is derived to characterize the possibility of meeting a desired contaminant concentration level. The decision analysis evaluates how the robustness and opportuneness change as a function of time since remediation and as a function of the fraction of contaminant mass removed. 相似文献
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The 12 May 2008 M7.9 Wenchuan earthquake in the People’s Republic of China represented a unique opportunity for the international
community to use commonly available GIS (Geographic Information System) tools, like Google Earth (GE), to rapidly evaluate
and assess landslide hazards triggered by the destructive earthquake and its aftershocks. In order to map earthquake-triggered
landslides, we provide details on the applicability and limitations of publicly available 3-day-post- and pre-earthquake imagery
provided by GE from the FORMOSAT-2 (formerly ROCSAT-2; Republic of China Satellite 2). We interpreted landslides on the 8-m-resolution
FORMOSAT-2 image by GE; as a result, 257 large landslides were mapped with the highest concentration along the Beichuan fault.
An estimated density of 0.3 landslides/km2 represents a minimum bound on density given the resolution of available imagery; higher resolution data would have identified
more landslides. This is a preliminary study, and further study is needed to understand the landslide characteristics in detail.
Although it is best to obtain landslide locations and measurements from satellite imagery having high resolution, it was found
that GE is an effective and rapid reconnaissance tool. 相似文献
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Multi-element analyses of more than 600 panned heavy-mineral concentrate samples from the Jameson Land area of central East Greenland were investigated by discriminant analysis which, combined with an a priori knowledge of the geology, was used to assist interpretation and classification the data. The importance of sample density, and the method and degree of sample grouping were investigated. Also the effect of using either the within-covariance or the pooled covariance matrices in the discriminant functions was studied.Discriminant analysis assumes the element concentrations to be normally distributed and that equality of within-covariances exists. These assumptions were not always met, and this was probably the main reason why one-third of the samples could not be classified. However, the study shows that interpretation of the data, although it is historical and forms only part of a regional reconnaissance survey, benefits from the application of discriminant analysis. 相似文献
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