The sample interval for the selection of extreme magnitudes plays an important part in the quality of Gumbel model fitting. A short sample interval can produce many observations, which is helpful in obtaining a reliably fitting model. However a short sample interval can bring many dummy ``observations', a condition which adversely biases the fitting. The short sample interval also increases the chance to introduce non-independent observations as well, which violates a basic requirement of the Gumbel model. On the other hand, a large time interval not only reduces the number of observations, but also enlarges the observation error. Thus, for Greece, the most suitable parameters of the third Gumbel extreme model are obtained by using a sample interval which produces minimum error. In consideration of the reliability of the seismic data, earthquakes with magnitude M 5.5 in Greece and its surrounding region after 1900 are used mainly in the present paper. In order to obtain well resolved contour maps with smooth changes a 2°× 2° cell with half-degree overlap strategy was used to scan the region. The most expected largest earthquake for the next fifty, one hundred and two hundred years are estimated for each cell. Likewise, the events with magnitude at a probability of 90\% of non-exceedance over the next fifty, one hundred and two hundred years are estimated for each cell. In parallel to this procedure we also analyze the 67 shallow seismic zones outlined by Papazachos and his colleagues and detail individual zone results where these are obtained. The most perceptible earthquake magnitude for the range of intensities I = {VI}, VII and VIII are also calculated. All results show that the areas around the Hellenic Arc and the Cephalonia Transform Fault for Greece have comparatively high frequency of destructive earthquakes accompanied by a high occurrence probability of moderate earthquakes (M 5.5). 相似文献
Present status of earthquake prediction and warning is reviewed with special emphasis on the Large-Scale Earthquake Countermeasures Act in Japan. Following possible regionalization of occurrences of a great earthquake by means of historical data analysis and crustal strain monitoring, statistics of earthquake precursors are presented along with the nature of precursors of various disciplines.The precursor time of the first-kind precursor depends on the magnitude of the main shock. The larger the magnitude is, the longer is the precursor time. The precursor of the second kind has a precursor time amounting to about a few hours, while that for the third kind ranges from a few to several ten days. A practical approach to actual prediction is suggested on the basis of the analysis of precursors. Difficulties in converting a prediction to a warning is briefly pointed out as well. 相似文献
As one of the most powerful tools to reduce the earthquake loss, the Earthquake Disaster Management [EDM] and Insurance [EI] have been highlighted and have had a great progress in many countries in recent years. Earthquake disaster management includes a series of contents, such as earthquake hazard and risk analysis, vulnerability analysis of building and infrastructure, earthquake aware training, and building the emergency response system. EI, which has been included in EDM after this practice has been done for many years, include these contents: insurance model, financing. This paper presents the development of china in EDM and EI. The main contents include: (1) the statue and trend of earthquake disaster management and insurance in china; (2) the progresses and new methods about the seismic risk zonation and vulnerability analysis, and the future developing trend, the application of GIS in earthquake disaster assessment is introduced; (3) the way and illustration in building the earthquake disaster e 相似文献
The magnitude 9.0 Tohoku or Sendai Earthquake ( Fig. 1 ) struck just off the northeast coast of Honshu, Japan on 11 March 2011 making it the fourth largest earthquake to be recorded since 1900, and the largest Japanese earthquake since modern seismometers were developed 130 years ago. Despite the earthquake being much more powerful than had been expected from the subduction zone east of Honshu, the earthquake preparedness of Japan resulted in relatively little earthquake damage—despite the protracted shaking with ground accelerations up to three times that of gravity. However, it was the resulting 10–15 metre high tsunami waves that wreaked havoc along the coastal plain, resulting in a death toll in the tens of thousands and an on‐going drama at the Fukushima I nuclear power plant. Modern seismology has its origins in the analyses of the 1906 San Francisco and 1923 Great Kanto earthquakes. The 2011 Tohoku (or ‘northeast’) earthquake looks set to similarly significantly advance our understanding of earthquakes and tsunamis due to the unprecedented volume of seismic, GPS, tide gauge and video data available. There is much information to be gained on how large earthquakes rupture, how buildings behave under prolonged severe shaking and how tsunamis propagate. Figure 1 Open in figure viewer PowerPoint Tohoku earthquake global displacement wavefield from IRIS. http://www.iris.edu/hq/files/iris_news/images/Sendai_RS.jpg 相似文献
