共查询到20条相似文献，搜索用时 15 毫秒
1.
The overall objective of this study is to improve the forecasting accuracy of the precipitation in the Singapore region by means of both rainfall forecasting and nowcasting. Numerical Weather Predication (NWP) and radar‐based rainfall nowcasting are two important sources for quantitative precipitation forecast. In this paper, an attempt to combine rainfall prediction from a high‐resolution mesoscale weather model and a radar‐based rainfall model was performed. Two rainfall forecasting methods were selected and examined: (i) the weather research and forecasting model (WRF); and (ii) a translation model (TM). The WRF model, at a high spatial resolution, was run over the domain of interest using the Global Forecast System data as initializing fields. Some heavy rainfall events were selected from data record and used to test the forecast capability of WRF and TM. Results obtained from TM and WRF were then combined together to form an ensemble rainfall forecasting model, by assigning weights of 0.7 and 0.3 weights to TM and WRF, respectively. This paper presented results from WRF and TM, and the resulting ensemble rainfall forecasting; comparisons with station data were conducted as well. It was shown that results from WRF are very useful as advisory of anticipated heavy rainfall events, whereas those from TM, which used information of rain cells already appearing on the radar screen, were more accurate for rainfall nowcasting as expected. The ensemble rainfall forecasting compares reasonably well with the station observation data. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
2.
This study examines a new methodology to predict the final seismic mortality from earthquakes in China. Most studies established the association between mortality estimation and seismic intensity without considering the population density. In China, however, the data are not always available, especially when it comes to the very urgent relief situation in the disaster. And the population density varies greatly from region to region. This motivates the development of empirical models that use historical death data to provide the path to analyze the death tolls for earthquakes. The present paper employs the average population density to predict the final death tolls in earthquakes using a case-based reasoning model from realistic perspective. To validate the forecasting results, historical data from 18 large-scale earthquakes occurred in China are used to estimate the seismic morality of each case. And a typical earthquake case occurred in the northwest of Sichuan Province is employed to demonstrate the estimation of final death toll. The strength of this paper is that it provides scientific methods with overall forecast errors lower than 20 %, and opens the door for conducting final death forecasts with a qualitative and quantitative approach. Limitations and future research are also analyzed and discussed in the conclusion. 相似文献
3.
We present a simple method for long- and short-term earthquake forecasting (estimating earthquake rate per unit area, time, and magnitude). For illustration we apply the method to the Pacific plate boundary region and the Mediterranean area surrounding Italy and Greece. Our ultimate goal is to develop forecasting and testing methods to validate or falsify common assumptions regarding earthquake potential. Our immediate purpose is to extend the forecasts we made starting in 1999 for the northwest and southwest Pacific to include somewhat smaller earthquakes and then adapt the methods to apply in other areas. The previous forecasts used the CMT earthquake catalog to forecast magnitude 5.8 and larger earthquakes. Like our previous forecasts, the new ones here are based on smoothed maps of past seismicity and assume spatial clustering. Our short-term forecasts also assume temporal clustering. An important adaptation in the new forecasts is to abandon the use of tensor focal mechanisms. This permits use of earthquake catalogs that reliably report many smaller quakes with no such mechanism estimates. The result is that we can forecast earthquakes at higher spatial resolution and down to a magnitude threshold of 4.7. The new forecasts can be tested far more quickly because smaller events are considerably more frequent. Also, our previous method used the focal mechanisms of past earthquakes to estimate the preferred directions of earthquake clustering, however the method made assumptions that generally hold in subduction zones only. The new approach escapes those assumptions. In the northwest Pacific the new method gives estimated earthquake rate density very similar to that of the previous forecast. 相似文献
4.
K. Z. Nanjo J. B. Rundle J. R. Holliday D. L. Turcotte 《Pure and Applied Geophysics》2006,163(11-12):2417-2432
Pattern Informatics (PI) technique can be used to detect precursory seismic activation or quiescence and make an earthquake forecast. Here we apply the PI method for optimal forecasting of large earthquakes in Japan, using the data catalogue maintained by the Japan Meteorological Agency. The PI method is tested to forecast large (magnitude m ≥ 5) earthquakes spanning the time period 1995–2004 in the Kobe region. Visual inspection and statistical testing show that the optimized PI method has forecasting skill, relative to the seismic intensity data often used as a standard null hypothesis. Moreover, we find in a retrospective forecast that the 1995 Kobe earthquake (m = 7.2) falls in a seismically anomalous area. Another approach to test the forecasting algorithm is to create a future potential map for large (m ≥ 5) earthquake events. This is illustrated using the Kobe and Tokyo regions for the forecast period 2000–2009. Based on the resulting Kobe map we point out several forecasted areas: The epicentral area of the 1995 Kobe earthquake, the Wakayama area, the Mie area, and the Aichi area. The Tokyo forecast map was created prior to the occurrence of the Oct. 23, 2004 Niigata earthquake (m = 6.8) and the principal aftershocks with 5.0 ≤ m. We find that these events were close to in a forecasted area on the Tokyo map. The PI technique for regional seismicity observation substantiates an example showing considerable promise as an intermediate-term earthquake forecasting in Japan. 相似文献
5.
介绍对瀑布沟水库用加卸载响应比和波速比监测预测水库诱发地震的实践过程,通过课题以往的预测和对应其后期实际发生的地震来分析,结果显示:地震频度库水加卸载响应比Yn和Cr值、库水下方地震波速比这两种方法都可以作为监测预测水库诱发地震的新方法。 相似文献
6.
H.K. Acharya 《Physics of the Earth and Planetary Interiors》1981,24(1):53-65
The distribution of large shallow earthquakes (magnitude ?5.5) in central Luzon, Philippines, related to the underthrusting of the Eurasian plate, is examined by the technique of pattern recognition. The objective of the study is (1) to forecast restricted zones of seismic activity, (2) to determine geological features which, in combination, are associated with the earthquakes in the environment of subduction, and (3) to determine whether more insight into regional seismicity can be gained by pattern recognition studies than by conventional seismicity studies. It appears from this analysis that large earthquakes occur (a) in a zone between the shallower portion of Manila Trench on its landward side and the belt of volcanoes and (b) on large strike-slip faults in the region such as Verde Island Passage fault and the Philippine fault. In these zones, large earthquakes occur at locations identified by large topographic relief in the vicinity and a high degree of fractured crust. In contrast to characteristics in California and central Asia, the intersection of faults nearby is not a major characteristic for large earthquakes in and near central Luzon. Topography and degree of fractured crust are important characteristics in all areas studied so far. Several earthquakes which are known to have occurred were considered unknown, and control experiments were carried out to determine whether the locations of these earthquakes would be identified as having potential for large earthquakes. The results of control experiments indicate that the pattern recognition technique is fairly successful in spatial forecasting if the known historical record is assumed almost complete for various major zones (85% in this case). It fails to forecast if information is totally lacking about earthquake activity on a tectonic feature. In the present study, a control experiment was able to correctly identify the locations of two of the largest earthquakes known to have occurred in the area. It was better able to identify locations of large earthquakes than a simple contouring of known earthquake locations would suggest. 相似文献
7.
By combining conventional grey correlation analysis,grey clustering method and grey forecasting methods with our multi-goal forecast thoughts and the techniques of grey time series processing,we develop six different grey earthquake forecast models in this paper,Using the record of major earthquakes in Japan from 1872 to 1995,we forecast future earthquakes in Japan.We develop an earthquake forecast model.By using the major earthquakes in Japan from 1872 to 1984,we forecast earthquakes from 1985 to 1995 and check the precision of the grey earthquake models.We find that the grey system theory can be applied to earthquake forecast.We introduce the above analysis methods and give a real example to evaluate and forecast.We also further discuss the problems of how to improve the precision of earthquake forecast and how to strengthen the forecast models in future research. 相似文献
8.
K. F. Tiampo J. B. Rundle W. Klein J. S. SÁ Martins 《Pure and Applied Geophysics》2004,161(9-10):1957-1968
— Attempts to understand the physics of earthquakes over the past decade generally have focused on applying methods and theories developed based upon phase transitions, materials science, and percolation theory to a variety of numerical simulations of extended fault networks. This recent work suggests that fault systems can be interpreted as mean-field threshold systems in metastable equilibrium (Rundle et al., 1995; Klein et al., 1997; Ferguson et al., 1999), and that these results strongly support the view that seismic activity is highly correlated across many space and time scales within large volumes of the earth’s crust (Rundle et al., 2000; Tiampo et al., 2002). In these systems, the time averaged elastic energy of the system fluctuates around a constant value for some period of time and is punctuated by major events that reorder the system before it settles into another metastable energy well. One way to measure the stability of such a system is to check a quantity called the Thirumalai-Mountain (TM) energy metric (Thirumalai and Mountain, 1993; Klein et al., 1996). In particular, using this metric, we show that the actual California fault system is ergodic in space and time for the period in question, punctuated by the occurrence of large earthquakes, and that, for individual events in the system, there are correlated regions that are a subset of the larger fault network. 相似文献
9.
Robert Shcherbakov Donald L. Turcotte John B. Rundle Kristy F. Tiampo James R. Holliday 《Pure and Applied Geophysics》2010,167(6-7):743-749
The objective of this paper is to quantify the use of past seismicity to forecast the locations of future large earthquakes and introduce optimization methods for the model parameters. To achieve this the binary forecast approach is used where the surface of the Earth is divided into l° × l° cells. The cumulative Benioff strain of m ≥ m c earthquakes that occurred during the training period, ΔT tr, is used to retrospectively forecast the locations of large target earthquakes with magnitudes ≥m T during the forecast period, ΔT for. The success of a forecast is measured in terms of hit rates (fraction of earthquakes forecast) and false alarm rates (fraction of alarms that do not forecast earthquakes). This binary forecast approach is quantified using a receiver operating characteristic diagram and an error diagram. An optimal forecast can be obtained by taking the maximum value of Pierce’s skill score. 相似文献
10.
根据 198 8年以来全国地震趋势会商会 (NMSC)所提出的各类地震学异常资料 ,研究每一年异常与下一年大陆地震的对应关系 .9a内 46种地震学方法所提出的93 2项异常资料表明 :在 1989～ 1993年间 ,用地震学预报地震方法的数量有一个增大过程 ;各种方法所提出的异常对应地震的比率在 0～ 48%之间 ,平均为 2 8%左右 ,这也与我国地震预报中预报区数的成功率相当 ;统计预报、区域应力场增强、地震条带、小震调制比和b值等方法有较高的地震对应率 ,而地震活动异常平静、分数维、异常震群、c值和地震窗等方法要差一些 ;用地震学方法预报地震最成功的年份为1989年 ,最差年份为 1990年 ;与预报区数的成功比率一样 ,其地震的对应比率并未随时间的推移而有所提高 .各种地震学方法的物理内涵及其与地震孕育的内在联系及各种地震学方法间相互关联问题是今后用地震学方法预报地震的研究课题 . 相似文献
11.
The reason for the failure to forecast the Wenchuan M_S8.0 earthquake is under study, based on the systematically collection of the seismicity anomalies and their analysis results from annual earthquake tendency forecasts between the 2001 Western Kunlun Mountains Pass M_S8.1 earthquake and the 2008 Wenchuan M_S8.0 earthquake. The results show that the earthquake tendency estimation of Chinese Mainland is for strong earthquakes to occur in the active stage, and that there is still potential for the occurrence of a M_S8.0 large earthquake in Chinese Mainland after the 2001 Western Kunlun Mountains Pass earthquake. However the phenomena that many large earthquakes occurred around Chinese Mainland, and the 6-year long quietude of M_S7.0 earthquake and an obvious quietude of M_S5.0 and M_S6.0 earthquakes during 2002～2007 led to the distinctly lower forecast estimation of earthquake tendency in Chinese Mainland after 2006. The middle part in the north-south seismic belt has been designated a seismic risk area of strong earthquake in recent years, but, the estimation of the risk degree in Southwestern China is insufficient after the Ning’er M_S6.4 earthquake in Yunnan in 2007. There are no records of earthquakes with M_S≥7.0 in the Longmenshan fault, which is one of reasons that this fault was not considered a seismic risk area of strong earthquakes in recent years. 相似文献
12.
We examined forecasting quiescence and activation models to obtain the conditional probability that a large earthquake will occur in a specific time period on different scales in Taiwan. The basic idea of the quiescence and activation models is to use earthquakes that have magnitudes larger than the completeness magnitude to compute the expected properties of large earthquakes. We calculated the probability time series for the whole Taiwan region and for three subareas of Taiwan—the western, eastern, and northeastern Taiwan regions—using 40 years of data from the Central Weather Bureau catalog. In the probability time series for the eastern and northeastern Taiwan regions, a high probability value is usually yielded in cluster events such as events with foreshocks and events that all occur in a short time period. In addition to the time series, we produced probability maps by calculating the conditional probability for every grid point at the time just before a large earthquake. The probability maps show that high probability values are yielded around the epicenter before a large earthquake. The receiver operating characteristic (ROC) curves of the probability maps demonstrate that the probability maps are not random forecasts, but also suggest that lowering the magnitude of a forecasted large earthquake may not improve the forecast method itself. From both the probability time series and probability maps, it can be observed that the probability obtained from the quiescence model increases before a large earthquake and the probability obtained from the activation model increases as the large earthquakes occur. The results lead us to conclude that the quiescence model has better forecast potential than the activation model. 相似文献
13.
14.
Majid Dehghani Bahram Saghafian Firoozeh Rivaz Ahmad Khodadadi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(3):861-874
In this research, a dynamic linear spatio-temporal model (DLSTM) was developed and evaluated for monthly streamflow forecasting. For parameter estimation, coupled expectation–maximization (EM) algorithm and Kalman filter was adopted. This combination enables the model to estimate the state vector and parameters concurrently. Different forecast scenarios including various combinations of upstream stations were considered for downstream station streamflow forecasting. Several statistical criteria, nonparametric and visual tests were used for model evaluation. Results indicated that the spatio-temporal model performed acceptably in almost all scenarios. The dynamic model was able to capitalize on coupled spatial and temporal information provided that there is spatial connectivity in the studied hydrometric stations network. Moreover, threshold level method was used for model evaluation in drought and wet periods. Results indicated that, in validation phase, the model was able to forecast the drought duration and volume deficit/over threshold, although volume deficit/over threshold could not be accurately simulated. 相似文献
15.
以华北地区1980——2010年资料为例,以单位边长的网格覆盖研究区,考察中小地震空间分布非空网格数的变化．网格尺度足够小则非空网格数趋于该时段的地震数,网格尺度足够大则非空网格数为1．实际资料显示,当空间网格尺寸大于0.5deg;之后,对结果稳定性的影响逐渐减弱．中小地震空间分布非空网格数的变化与ldquo;背景rdquo;地震活动的空间扩展（增强）或收缩（平静）有关．不同网格尺寸条件下的非空网格数有基本一致的变化趋势,可能间接反映了区域应力的短时扰动或起伏．小地震有更高的丛集特性,随着震级下限的提高,不同网格尺寸非空网格数之间差异逐渐变小．华北地区小震活动非空网格数的频次分布符合统计正态分布,因而给定置信概率、依据正态分布密度函数可计算非空网格数的ldquo;正常rdquo;分布范围,超出此范围的数据可视为异常．统计显示,就华北地区而言,中小地震非空网格数ldquo;平静rdquo;型异常的预测效率最低,ldquo;增强rdquo;型异常具有最高的报警对应率,而同时考虑ldquo;增强rdquo;及ldquo;平静rdquo;的异常判据则具有最高的预报评分．这也意味着,华北中强地震前以ldquo;增强rdquo;型的中小地震活动异常为主．研究结果还显示,小地震时空活动格局的改变与后续中强地震似乎具有更强的统计关联特性． 相似文献
16.
I. G. Kissin 《Izvestiya Physics of the Solid Earth》2013,49(4):587-600
The studies on forecasting earthquakes, which reached their greatest development in the last quarter of the past century, have not solved this problem. The present paper sheds light on this. It is concluded that the philosophy of investigations should be profoundly reconceived, and a systematic approach, which is extensively used for solving complex multicomponent problems, should be applied. If applied to earthquake prediction, it could reveal the weak points of the analysis and determine the necessary volume of observations; it would allow geophysicists to pass from poorly substantiated attempts at forecasting to the systematic study of all aspects of the problem which would provide the basis for the forecast. The current state of the problem and its composing subsystems, the geophysical environment and its stress-strain state, are discussed. The questions that have not been previously given due attention, namely, the relationship between the earthquakes and the paths of fluid migration, the reliability of precursors, and the factors responsible for the lack of their correspondence to the parameters of seismic rupture are analyzed. It is concluded that the current networks of seismic and other geophysical observations are incapable of recording the premonitory signs of an impending earthquake and providing the basis for forecasting large earthquakes. 相似文献
17.
In this study, the climate teleconnections with meteorological droughts are analysed and used to develop ensemble drought prediction models using a support vector machine (SVM)–copula approach over Western Rajasthan (India). The meteorological droughts are identified using the Standardized Precipitation Index (SPI). In the analysis of large‐scale climate forcing represented by climate indices such as El Niño Southern Oscillation, Indian Ocean Dipole Mode and Atlantic Multidecadal Oscillation on regional droughts, it is found that regional droughts exhibits interannual as well as interdecadal variability. On the basis of potential teleconnections between regional droughts and climate indices, SPI‐based drought forecasting models are developed with up to 3 months' lead time. As traditional statistical forecast models are unable to capture nonlinearity and nonstationarity associated with drought forecasts, a machine learning technique, namely, support vector regression (SVR), is adopted to forecast the drought index, and the copula method is used to model the joint distribution of observed and predicted drought index. The copula‐based conditional distribution of an observed drought index conditioned on predicted drought index is utilized to simulate ensembles of drought forecasts. Two variants of drought forecast models are developed, namely a single model for all the periods in a year and separate models for each of the four seasons in a year. The performance of developed models is validated for predicting drought time series for 10 years' data. Improvement in ensemble prediction of drought indices is observed for combined seasonal model over the single model without seasonal partitions. The results show that the proposed SVM–copula approach improves the drought prediction capability and provides estimation of uncertainty associated with drought predictions. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
18.
F.F. Evison 《Physics of the Earth and Planetary Interiors》1977,15(4):P19-P23
Prior swarms near the sites of eleven moderate to large earthquakes from diverse tectonic settings in the New Zealand and California regions yield regressions for the estimation of magnitude and time of occurrence, and thus offer a possible basis for long-range forecasting. 相似文献
19.
20.
Ground-motion prediction equations for the intermediate depth Vrancea (Romania) earthquakes 总被引：2，自引：1，他引：1
Vladimir Sokolov Klaus-Peter Bonjer Friedemann Wenzel Bogdan Grecu Mircea Radulian 《Bulletin of Earthquake Engineering》2008,6(3):367-388
We present the regional ground-motion prediction equations for peak ground acceleration (PGA), peak ground velocity (PGV),
pseudo-spectral acceleration (PSA), and seismic intensity (MSK scale) for the Vrancea intermediate depth earthquakes (SE-Carpathians)
and territory of Romania. The prediction equations were constructed using the stochastic technique on the basis of the regional
Fourier amplitude spectrum (FAS) source scaling and attenuation models and the generalised site amplification functions. Values
of considered ground motion parameters are given as the functions of earthquake magnitude, depth and epicentral distance.
The developed ground-motion models were tested and calibrated using the available data from the large Vrancea earthquakes.
We suggest to use the presented equations for the rapid estimation of seismic effect after strong earthquakes (Shakemap generation)
and seismic hazard assessment, both deterministic and probabilistic approaches. 相似文献