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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
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云南地区地震灾情特点 总被引：3，自引：0，他引：3
本文分析了有记载以来发生在云南的一百多次破坏性地震,其中包括七十年代发生在通海、昭通、龙陵三次七级以上地震的灾情,概述了云南地区地震灾害的一般性特征和地方性特征,为减轻地震灾害对策研究参考。 相似文献
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本文利用晋冀蒙交界地区1500年以来记录较完整的MS5.0及以上历史地震烈度资料和2000年以来的地震活动资料，分别进行地震灾害危险性和地震活动性分析。首先，利用ArcGIS将历史地震烈度资料数字化，没有等震线记录的地震用烈度衰减关系计算烈度圈半径。将研究区划分成0.1°×0.1°的网格，将烈度资料分配到与之相交的每个网格，并用烈度-频度关系计算每个网格的烈度a、b值。基于地震发生遵从泊松分布的假定，估算未来50年内晋冀蒙交界区遭受某一地震烈度的超越概率。同时，计算50年超越概率10%对应的地震烈度，计算结果表明张家口蔚县、阳原和山西广灵县周边地区的地震危险性较高。最后，采用中小地震能量密度值计算方法，对2000年以来的现今地震活动进行定量分析，与历史地震烈度资料分析结果进行对比，发现中小地震活动圈定的危险区与历史地震烈度资料评估计算的概率高值区相对应，因此，这两种方法可为晋冀蒙交界地区的地震活动性和危险性评价提供参考。 相似文献
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城市震害预测中设定地震的确定问题 总被引：2，自引：0，他引：2
提出了一个确定震害预测中设定地震的方法,包括：确定贡献量最大的潜在震源区、潜在震源区内贡献量最大的震级档和设定地震的构造位置等。以福建省泉州市为例,获得５０年超赵概率６３％、１０％和２％等３个概率水平下的设定地震。本文给出的设定地震方法纵使了确定论方法和概率论方法的优点,有助于地震危险性分析方法的发展。 相似文献
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统计分析了中国大陆１９００年以来所有发生在东北的５级以上的学震及其与中国大陆２６个地震带６级以上（其中东部为５级以上）地震活动的相关性。结果表明７级以上深震有可能引发中国大陆地震活动进入应变能大释放阶段。其中与东北深震统计相关最高的地震带是：金沙江地震带、南天山地震带澜沧江－眉公河地震带以及巴颜喀拉山地震带;在中国东商地区相关性相对较高的地区是：郯城－营口地震带、长江下游－南黄海地震带以臁东南沿海 相似文献
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Seismic damage evaluation in urban areas using the capacity spectrum method: Application to Barcelona 总被引：8，自引：0，他引：8
Alex H. Barbat Luis G. Pujades Nieves Lantada 《Soil Dynamics and Earthquake Engineering》2008,28(10-11):851
Conceptual aspects related to seismic vulnerability, damage and risk evaluation are discussed first, together with a short review of the most widely used possibilities for seismic evaluation of structures. The capacity spectrum method and the way of obtaining seismic damage scenarios for urban areas starting from capacity and fragility curves are then discussed. The determination of capacity curves for buildings using non-linear structural analysis tools is then explained, together with a simplified expeditious procedure allowing the development of fragility curves. The seismic risk of the buildings of Barcelona, Spain, is analyzed in the paper, based on the application of the capacity spectrum method. The seismic hazard in the area of the city is described by means of the reduced 5% damped elastic response spectrum. The information on the buildings was obtained by collecting, arranging, improving and completing a broad database of the dwellings and current buildings. The buildings existing in Barcelona are mainly of two types: unreinforced masonry structures and reinforced concrete buildings with waffled-slab floors. The ArcView software was used to create a GIS tool for managing the collected information in order to develop seismic risk scenarios. This study shows that the vulnerability of the buildings is significant in Barcelona and, therefore, in spite of the low-to-moderate seismic hazard in the region, the expected seismic risk is considerable. 相似文献
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Faulting, shallow seismicity (0–30 km), and seismic hazard of the Costa Rican Central Valley were analyzed. Faults in the study area are oriented northwest or northeast. There is an active fault system in the south flank of the Central Volcanic Ridge and another in the north flank of the Talamanca Ridge. Faults of these systems have generated 15 destructive earthquakes in the area during the last 228 years all of them shallow and their locations show one cluster near the Poas Volcano and another southward the Central Valley. These earthquakes have damaged cities of the Central Valley, two of them destroyed Cartago city and almost 1000 people were killed. Regarding recent seismicity, there are three main seismic sources at the Central Volcanic Ridge: Irazu, Bajo de la Hondura and Poas and other three in the Talamanca Ridge: Puriscal, Los Santos and Pejibaye.A seismic hazard map for the Metropolitan Area of San José has been elaborated, based on local tectonic and seismic information. The area for the hazard computation covers an area of 20×15 km2 and includes the zone where the most population and socioeconomic activities are concentrated. The computation analysis are based on areas zones and faults, each one characterized by recurrence parameters, geometry, minimum and maximum magnitude and source depth. A recent local spectral attenuation model, which includes relations for shallow crustal sources and subduction zone earthquakes, has been applied in this study. The seismic hazard results are presented in terms of contour plots of estimated peak ground acceleration (PGA) for bedrock conditions for return period of 50, 100 and 500 years. In the Central Park of San Jose City the following PGA values were found: 0.29g for 50 years, 0.36g for 100 years, and 0.53g for 500 years. 相似文献
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从历史最大地震烈度分布图分析,可知揭阳、汕头、潮州三市位于Ⅶ～Ⅷ度高地震烈度区。该城市群地震灾害有以下特点:市区发生破坏性地震的潜在危险性大;地震时市区地震烈度高,地震灾害大,损失严重。采用宏观经济易损性的地震损失分析方法,重演该区的历史破坏性地震。分析表明:抓好该区的防震减灾工作是保持社会和经济建设持续发展的一项重要工作。 相似文献
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Mihailo D. Trifunac Maria I. Todorovska 《Soil Dynamics and Earthquake Engineering》2004,24(3):225-239
This paper compares the distribution of damage from the San Fernando, 1971, and Northridge, 1994, earthquakes. Both events had similar size, occurred on blind thrust faults beneath the densely populated San Fernando Valley of the Los Angeles metropolitan area, and hence offer a rare opportunity to compare the effects of the two earthquakes. In a previous study of the distribution of red-tagged (‘unsafe’) buildings and of breaks in the water distribution system caused by the Northridge earthquake, the authors discovered that buildings were damaged less where the soil response was not linear (as indicated by the breaks in the water pipes), except in localized areas of very severe shaking (peak ground velocity exceeding 150 cm/s). The study in this paper shows that the same applies to the damage caused by the San Fernando earthquake, and that the areas with severely damaged buildings (so called ‘gray zones’) for both earthquakes overlapped. This reoccurrence of damage within the same area is interpreted to result from some specific properties of local soil and geology. These properties are not fully understood at present, but should be explored to provide a basis for a new tool for forecasting microzonation maps, and reducing future seismic hazard. 相似文献
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陕西省"十五"数字测震台网的建成并投入运行,极大地提高了陕西测震台网地震监测能力和地震速报能力,并成功地经受了四川汶川8.0级地震的考验。在2008年5月12日14时28分汶川8.0级地震后至5月31日,陕西测震台网速报地震669个,其中在地震速报规定范围内速报5级以上地震11个。在应对2009年11月5日陕西高陵4.4级地震(Ⅰ类速报地震)和2013年7月22日甘肃岷县6.6级地震(Ⅲ类速报地震)及余震序列时,两个主震各种速报参数偏差全部符合地震速报规定对相应类别地震速报的要求。 相似文献
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云南近期姚安、澄江及丘北地震的孕育 总被引：1，自引：1，他引：1
从地震学的角度对姚安、澄江和丘北地震的孕育进行追踪研究，结果表明：云南地区3个月时间内发生多次中强震，震前云南省地震学的波速比，小震调制比以及震源深度等多项参数出现了中期同步异常，并且有区域性中小地震活跃，能量的加速一平静过程以及前兆震群出现等明显的近场异常，表明云南地区快速发生的多次中强地震，在地震学方面出现明显的中短期异常的孕震特征。 相似文献
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Zhang Guomin 《中国地震研究》2007,21(1):1-15
The paper describes firstly the principles and scientific train of thought involved in determining the significant seismic monitoring and protection regions (SSMPR) in China. The principles include the gradation principle, i.e. the national level SSMPR and the provincial level SSMPR, the principle of highlighting priorities, namely, the area of an SSMPR should be a fraction of the total area of the country or of the respective province, but the earthquake losses incurred in SSMPR should be a major proportion of the national or provincial ones. The scientific train of thought adopted is to determine the SSMPR on the basis of seismic hazard assessment and loss estimation. Secondly, it reviews the achievements in determining the SSMPRs for the period from 1996 to 2005. The result shows that 10 strong earthquakes occurred during that period in the areas with earthquake monitoring and prediction capability available on the Chinese continent, 8 of which occurred in SSMPRs with the economic loss and death toll accounting for 67% and 92% of the total loss on the Chinese mainland. Lastly, the paper introduces preparatory research for determining the SSMPR for the period from 2006 to 2020, including decade-scale mid-and long-range seismic risk assessment based on seismology, seismogeology, geodesy, earthquake engineering, sociology and stochastics and so on, and the national seismic risk probability map, the seismic hazard (intensity) map, earthquake disaster losses map and the comprehensive seismic risk index, etc. obtained for the period of 2006 to 2020. 相似文献
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The occurrence of the Algiers earthquake (M 6.8) of May 21, 2003, has motivated the necessity to reassess the probabilistic seismic hazard of northern Algeria. The fact that this destructive earthquake took place in an area where there was no evidence of previous significant earthquakes, neither instrumental nor historical, strongly encourages us to review the seismic hazard map of this region. Recently, the probabilistic seismic hazard of northern Algeria was computed using the spatially smoothed seismicity methodology. The catalog used in the previous computation was updated for this review, and not only includes information until June 2003, but also considers a recent re-evaluation of several historical earthquakes. In this paper, the same methodology and seismicity models are utilized in an effort to compare this methodology against an improved and updated seismic catalog. The largest mean peak ground acceleration (PGA) values are obtained in northernmost Algeria, specifically in the central area of the Tell Atlas. These values are of the order of 0.48 g for a return period of 475 years. In the City of Algiers, the capital of Algeria, and approximately 50 km from the reported epicenter of this latest destructive earthquake, a new mean PGA value of 0.23 g is obtained for the same return period. This value is 0.07 g greater than that obtained in the previous computation. In general, we receive greater seismic hazard results in the surrounding area of Algiers, especially to the southwest. The main reason is not this recent earthquake by itself, but the significant increase in the mmax magnitude in the seismic source where the city and the epicenter are included. 相似文献
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新疆南天山东段地震平静相关问题探讨 总被引：1，自引：0，他引：1
分析了南天山东段地震平静相关问题。得到如下结论：①将平静现象分为震前平静、震后平静．场兆平静、无震平静可能更能客观地反映平静状态;②南天山东段4级地震平静6个月以上具有前兆意义;③5级地震发生前的打破平静现象分为两类,由4级地震打破平静的5级地震其发震位置与4级地震关系密切,由5级地震打破平静的地震一般发生在地震弱活动区或南天山东段5级地震成组活动时期,前兆现象较难捕捉;④南天山东段5级地震最长平静时间为57个月。 相似文献