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1.
On a novel approach to forecast sparse rare events: applications to Parkfield earthquake prediction 总被引：1，自引：1，他引：0
Natural Hazards - Rare events are plentiful in nature and most of them have devastating consequences on human lives and property. Modeling such events is intrinsically challenging due to their very... 相似文献
2.
Chih-Hsiang Ho 《Mathematical Geology》1992,24(7):775-787
In an important paper, Mulargia et al. (1987) address the importance of quantitative and objective identification of different regimes of a volcano. They develop a procedure based on the two-sample Kolmogorov-Smirnov (K-S) statistic. The K-S test is a general-purpose test that discriminates between two data sets as belonging to two different regimes based on their empirical distribution functions. The empirical distribution function is designed to describe the aggregate behavior of the volcanic activity, and it is constructed from the orders of the length of the collected repose times in each data set. In this article, we use the idea of statistical process control to distinguish between the variation inherent in the observed repose times and the extraordinary variation that signals a real change in the regimes. We construct a table of control limits, and we demonstrate the procedure of regime identification based on a simple control chart. It shows a point outside the control limits almost as soon as the process enters a new regime. The basis of the statistical process control mechanism is a simple Poisson process, which is state of the art. The proposed control charting procedure is an eruption by eruption procedure, which follows the original chronological order of the eruptions. This procedure is applied to the eruptive history of the Mount Etna volcano. The application shows schematically that the procedure presents a visual interpretation of the identified regimes and can be practically translated for tabular or manual use. 相似文献
3.
Jen-Chen Fan Che-Hsin Liu Chih-Hsiang Yang Hsiao-Yu Huang 《Environmental Geology》2009,57(7):1509-1519
In this study, soil samples collected from the sides of two streams with high debris flow potential at Shenmu and Fengchiou
village in Nantou County, Taiwan, were used for seepage tank tests in the laboratory. While the tests were being conducted,
observations were made to investigate the relationships among displacement of the slope, quality of the seepage water and
occurrence of mass movement. The results showed that according to the change rate, displacement could be divided into two
stages, namely, the initial failure displacement stage and primary failure displacement stage. While the displacement of the
slope was in primary failure displacement stages, the probability of slope failure became much higher. Before general slope
failure, electrical conductivity (EC) and sulfate ion (SO4
2−) concentration of the seepage water increased significantly. The time when EC of the seepage water started to increase rapidly
was much earlier than that when displacement of the slope started to increase significantly. Therefore, from the hazard mitigation
view, there will be a longer time for response if EC of the seepage water was monitored. 相似文献
4.
Chih-Hsiang Ho 《Mathematical Geology》1992,24(4):347-364
In this article, we model the volcanism near the proposed nuclear waste repository at Yucca Mountain, Nevada, U.S.A. by estimating the instantaneous recurrence rate using a nonhomogeneous Poisson process with Weibull intensity and by using a homogeneous Poisson process to predict future eruptions. We then quantify the probability that any single eruption is disruptive in terms of a (prior) probability distribution, since not every eruption would result in disruption of the repository. Bayesian analysis is performed to evaluate the volcanic risk. Based on the Quaternary data, a 90% confidence interval for the instantaneous recurrence rate near the Yucca Mountain site is (1.85×10–6/yr, 1.26×10–5/yr). Also, using-these confidence bounds, the corresponding 90% confidence interval for the risk (probability of at least one disruptive eruption) for an isolation time of 104 years is (1.0×10–3, 6.7×10–3), if it is assumed that the intensity remains constant during the projected time frame. 相似文献
5.
Chih-Hsiang Ho 《Mathematical Geology》1991,23(2):167-173
A simple Poisson process is more specifically known as a homogeneous Poisson process since the rate was assumed independent of time t. The homogeneous Poisson model generally gives a good fit to many volcanoes for forecasting volcanic eruptions. If eruptions occur according to a homogeneous Poisson process, the repose times between consecutive eruptions are independent exponential variables with mean=1/. The exponential distribution is applicable when the eruptions occur at random and are not due to aging, etc. It is interesting to note that a general population of volcanoes can be related to a nonhomogeneous Poisson process with intensity factor(t). In this paper, specifically, we consider a more general Weibull distribution, WEI (, ), for volcanism. A Weibull process is appropriate for three types of volcanoes: increasing-eruption-rate (>1), decreasing-eruption-rate (<1), and constant-eruption-rate (=1). Statistical methods (parameter estimation, hypothesis testing, and prediction intervals) are provided to analyze the following five volcanoes: Also, Etna, Kilauea, St. Helens, and Yake-Dake. We conclude that the generalized model can be considered a goodness-of-fit test for a simple exponential model (a homogeneous Poisson model), and is preferable for practical use for some nonhomogeneous Poisson volcanoes with monotonic eruptive rates. 相似文献
6.
Hawaiian volcanoes such as Kilauea and Mauna Loa have drawn the attention of researchers for quite some time and numerous theories abound hinting at a possible inverse relationship between the two. Most of these analyses are intrinsically qualitative and are bereft of data-driven statistical justification. The present work attempts to address this issue adopting a more mathematical approach and endeavours to examine the existence of such a relationship through the novel use of a smoothing statistic termed as the empirical recurrence rates ratio. Additionally, it is shown that useful knowledge about the possible interplay between these two volcanoes is coded into this single statistic and based on it; construction of new dependence measures such as the two introduced, becomes simpler and much more intuitive. The recent decade is witnessing an increased activity of Kilauea and the methods proposed here can be successfully implemented to safeguard human lives and property against the unpredictable advances of all-engulfing molten lava flow. 相似文献
7.
Multiple-expert hazard/risk assessments have considerable precedent, particularly in the Yucca Mountain site characterization
studies. A certain amount of expert knowledge is needed to interpret the geological data used in a probabilistic data analysis.
As may be the situation in science, experts disagree on crucial points. Consequently, lack of consensus in some studies is
a sure outcome. In this paper, we present a Bayesian approach to statistical modeling in volcanic hazard assessment for the
Yucca Mountain site. Specifically, we show that the expert opinion on the site disruption parameterp is incorporated into the prior distribution, π(p), based on geological information that is available. Moreover, π(p) can
combine all available geological information motivated by conflicting but realistic arguments (e.g., simulation, cluster analysis,
structural control, ..., etc.). The incorporated uncertainties about the probability of repository disruptionp
eventually will be averaged out by taking the expectation over π(p). We use the following priors in the analysis: (1) priors
selected for mathematical convenience: Beta (r,s) for (r,s) = (2, 2), (3, 3), (5, 5), (2, 1),(2, 8), (8, 2), and (1, 1);and (2) three priors motivated by expert knowledge. Sensitivity analysis is performed for each prior distribution. Our study
concludes that estimated values of hazard based on the priors selected for mathematical simplicity are uniformly higher than
those obtained based on the priors motivated by expert knowledge. And, the model using the prior, Beta (8, 2), yields the
highest hazard (=2.97 × 10-2
. The minimum hazard is produced by the “three-expert prior” (i.e., values of
p
are equally likely for
p = 10-3, 10-2,and 10-1
. The estimate of the hazard is 1.39 × 10-3, which is only about one order of magnitude smaller than the maximum value. The term, “hazard, ” is defined as the probability
of at least one disruption of a repository at the Yucca Mountain site by basaltic volcanism for the next 10,000 years. 相似文献
8.
Models that calculate the probability that a new volcano or a dike from a nearby eruption will intersect the footprint of the proposed high-level nuclear waste repository are generalized based on a conceptual model developed for the space transportation industry. The proposed hazard area, defined such that every new eruption that occurs there will disrupt the repository, plays a fundamental role in developing probability models. This hazard area is used not only to hedge the uncertainties in predicting patterns of future volcanic activity, but also to account for the characteristics of a new eruption during the post-closure performance period of an underground geologic repository. The paper discusses the advantages of probability comparisons, capabilities of conservativeness measurements and expert-elicitation on model parameters, and the implications to the proposed repository.Paper funded by a contract from the Agency for Nuclear Projects, State of Nevada, USA. 相似文献
9.
We present a 3-D Poisson model that permits identification and quantification of volcanic phenomena distributed through space and evolving in time (i.e., spatiotemporal data). Specifically, the model: (1) is volcanologically informative in solving problems of volcanic risk/hazard which depends on the location and time of future events; (2) contains model fitting computation algorithms that are efficient; and (3) is flexible enough to handle a large class of volcanic risk/hazard studies. Furthermore, we apply the model fitting techniques developed in this paper to the volcanic data from the Yucca Mountain project to demonstrate a unified volcanic hazard analysis. This study also evaluates the sensitivity of the statistical models developed by experts who have addressed the volcanic hazard/risk assessment problem near the Yucca Mountain region. 相似文献
10.
Toxicity assessments of nanoscale zerovalent iron and its oxidation products in medaka (Oryzias latipes) fish 总被引：1，自引：0，他引：1
Iron-based nanotechnologies are increasingly used for environmental remediation; however, toxicologic impacts of iron nanoparticles on the aquatic ecosystem remain poorly understood. We treated larvae of medaka fish (Oryzias latipes) with thoroughly characterized solutions containing carboxymethyl cellulose (CMC)-stabilized nanoscale zerovalent iron (nZVI), aged nanoscale iron oxides (nFe-oxides) or ferrous ion (Fe[II]) for 12-14 days' aqueous exposure to assess the causal toxic effect(s) of iron NPs on the fish. With the CMC-nZVI solution, the dissolved oxygen level decreased, and a burst of reactive oxygen species (ROS) was generated as Fe(II) oxidized to ferric ion (Fe[III]); with the other two iron solutions, these parameters did not significantly change. CMC-nZVI and Fe(II) solutions caused acute lethally and sublethally toxic effects in medaka larvae, with nFe-oxide-containing solutions causing the least toxic effects. We discuss modes of toxic action of iron NPs and chronic toxic effects in terms of hypoxia, Fe(II) toxicity and ROS-mediated oxidative damage. 相似文献