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非齐次复合 Poisson地震发生概率模型研究 总被引：4，自引：0，他引：4
依据现有地震发生概率模型合理性与局限性以及地震估计的基本思想提出五类非齐次复合 Poisson 地震发生概率模型,阐述各模型的基本特点及可能实用的前提。 以华北地区的地震序列为例大致模拟了不同阶段的地震发生概率水平,分析表明非齐次复合 Poisson 地震发生概率模型更能反映地震发生的时间不均匀性。 相似文献
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在系统地分析了目前各种测震学地震预报方法科学思路的基础上,认为测震学地震预报方法基本上可以分为两大类。一类是以已经发生的一些地震作为未来可能发生的地震的“因”,即由于已经发生的地震对区域应力场的影响,导致未来发生较强地震。这一类包括的预报方法较多,如空区、条带、ｂ值、地震迁移、相关地震等等及其由此衍生出来的各种方法。另一类是把已经发生的一些地震作为区域应力场增强的“果”,即已经发生的地震是区域应力场增强过程中的一种反映,而未来地震不一定是已经发生的地震所导致的结果。这一类包括“地震窗口”、小震群活动等方法。针对第一类方法,各种预报方法都是力图从地震三要素中提取未来地震的信息,而具体作法又都是利用地震三要素这个多维空间的某个剖面。为了从地震活动诸要素的多维空间提取综合信息,我们对每个地震加入了破裂面方位,构成了地震第四要素,并依据地震４要素建立了地震综合效应场函数。地震综合效应场函数概括了多种测震学地震预报方法的科学思路和预报经验,从而可以形成测震学的综合预报方法。 相似文献
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本文回顾总结了2020年地震活动,从全球到局部,呈现了全球、中国和四川的地震活动概况;分析了全球、中国和四川地震活动的特征;记叙了2020年四川区域内发生的突出地震事件;追踪了2008年汶川8.0级地震以来四川区域内发生的3次7级以上地震和2019年发生的长宁6.0级地震震群的余震活动.结果显示:2020年全球MS≥7... 相似文献
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长江三峡工程库首区胡家坪M_S4.1水库诱发地震研究 总被引：1，自引：0，他引：1
本文在系统收集有关资料并对地震现场进行考察的基础上,分析了2008年11月22日发生在秭归县归州镇香溪村胡家坪 M_S4.1级地震及其发生的地质-水文地质与地震活动背景条件,介绍了地震灾害. 并进一步讨论了相关的地震前兆异常、地震成因等科学问题,认为该地震是在水库水体荷载与库水下渗的共同作用下沿仙女山断裂发生的构造型水库诱发地震, 并认为震前有一定的前兆异常,这个地震的发生除了水库蓄水作用之外,可能还与汶川地震对该区应力场的影响有关. 相似文献
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阪神大震灾至今 ( 1月 1 7日 )整整 6周年了。去年 1 0月 ,日本西部地区发生了震级为7.3的鸟取县西部地震 ,人们再次感受到地震的恐惧。过去 ,四国至东海地区的近海一带一直有规律性地反复发生海沟型巨大地震 ,而在每次海沟型地震发生的前后其周边地区都频繁发生内陆型地震。部分地震学家认为 ,2 0 40年前后将要发生 M 8南海地震 ,在此之前 ,内陆地区将会不断发生大地震 ,尤其是日本海一侧很可能会连锁式地发生地震。大震发生后 ,日本西南部已进入地震活跃期。为确保人身安全 ,应提高警惕 ,常备不懈。南海地震“至下次南海地震之前 ,M 6.5… 相似文献
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淮河流域焦岗湖水质参数时空变化及影响因素 总被引：3，自引：1，他引：2
焦岗湖是淮河左岸一个天然湖泊,集防洪、灌溉、养殖、旅游等多种功能于一体.利用焦岗湖4个季节水质监测数据,运用Kriging方法,分析焦岗湖水质参数的时空变化及影响因素.结果表明:由于受水文季节变化过程及人类活动等综合影响,焦岗湖水质参数在时间及空间上均存在一定差异.从时间变化来看,夏季透明度较低、秋季较高;溶解氧浓度在春、冬季显著高于夏、秋季;总氮、总磷浓度与高锰酸盐指数均表现为夏季最高、秋季最低.从空间变化来看,4个季节的透明度空间差异较为显著;溶解氧浓度在春、冬季空间分布较为均匀,夏季呈现中心高周围低的变化趋势,秋季则表现为西高东低;总磷浓度春季分布较为均匀,夏、秋及冬季则呈西高东低之势;高锰酸盐指数在春、秋季节呈现东高西低之势,夏季高浓度主要集中在湖区北部,冬季浓度变化不大. 相似文献
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大通湖及东洞庭湖区生物体重金属的水平及其生态评价 总被引：4，自引：0，他引：4
于2005年11月采集了大通湖及东洞庭湖区湖水和水生生物样品,并测定了水和水生生物样品中重金属(Cd、Pb、Hg、As)的含量,并对湖区生物体重金属进行了污染评价.研究结果表明,大通湖及东洞庭湖区湖水中重金属含量较小,绝大部分采样点水质都属于国家Ⅰ类水标准;水生生物体内CD、Pb含量为虾＞螺＞鱼,Hg的含量为鱼＞螺＞虾,As的含量为螺＞虾＞鱼;而鱼类重金属含量则为底栖鱼类＞中上层鱼类,肉食性鱼类＞植食性鱼类.大通湖及东洞庭湖区生物体中CD、Pb的污染指数为虾＞螺＞鱼,Hg的污染指数则为鱼＞螺＞虾,As的污染指数则为螺＞虾＞鱼. 相似文献
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Spatial and temporal distributions of the trends of extreme precipitation indices were analysed between 1986 and 2005, over the Iberian Peninsula (IP). The knowledge of the patterns of extreme precipitation is important for impacts assessment, development of adaptation and mitigation strategies. As such, there is a growing need for a more detailed knowledge of precipitation climate change.This analysis was performed for Portuguese and Spanish observational datasets and results performed by the Weather Research and Forecast (WRF) model forced by the ERA-Interim reanalysis. Extreme precipitation indices recommended by the Expert Team for Climate Change Detection Monitoring and Indices were computed, by year and season. Then, annual and seasonal trends of the indices were estimated by Theil-Sen method and their significance was tested by the Mann-Kendal test. Additionally, a second simulation forced by the Max Planck Institute Earth System Model (MPI-ESM), was considered. This second modelling configuration was created in order to assess its performance when simulating extremes of precipitation.The annual trends estimated for the 1986–2005, from the observational datasets and from the ERA-driven simulation reveal: 1) negative statistically significant trends of the CWD index in the Galicia and in the centre of the IP; 2) positive statistically significant trends of the CDD index over the south of the IP and negative statistically significant trends in Galicia, north and centre of Portugal; 3) positive statistically significant trends of the R75p index in some regions of the north of the IP; 4) positive statistically significant trends in the R95pTOT index in the Central Mountains Chain, Leon Mountains and in the north of Portugal.Seasonally, negative statistically significant trends of the CWD index were found in Galicia, in winter and in the south of the IP, in summer. Positive statistically significant trends of the CWD index were identified in the Leon Mountains, in spring, and in Galicia, in autumn. For the CDD index, negative statistically significant trends were seen in Valencia, in the spring, and, in Galicia and Portugal (north and centre), in summer. Positive statistically significant trends of the CDD index were found: in the east of the IP, in the winter; in the Cantabrian Mountain, in the spring; and, in the south of the IP, in summer. Regarding to the R75p index, negative statistically significant trends were found in Galicia, in winter and positive statistically significant trends in the north of Portugal, in spring and in the Central Mountains Chain and north of Portugal, in autumn. For the R95pTOT index, negative statistically significant trends were found over the Sierra Cuenca and Sierra Cazorla, in winter and positive statistically significant trends were found over the Sierra Cebollera, in winter and in Castile-la Mancha region, in spring.The results of the annual and seasonal trends of the extreme precipitation indices performed for observational datasets and the simulation forced by ERA-Interim, are similar. The results obtained for the simulation forced by MPI-ESM are not satisfactory, and can be a source of criticism for the use of simulation forced by MPI-ESM in this type of climate change studies. Even for the relatively short period used, the WRF model, when properly forced is a useful tool due to the similar results of Portuguese and Spanish observational datasets and the simulation forced by ERA-Interim. 相似文献
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In order to understand the various processes responsible for siltation in the entrance channel and in the sand bar area near the old Mangalore port, variations in temperature, salinity, suspended sediment load, currents and extinction coefficient in the Netravathi-Gurpur Estuary and in the sea near the sand bar were studied in relation to tides during monsoon, post-monsoon and pre-monsoon seasons. The hydrographic characteristics in the estuary showed marked seasonal changes and were influenced by tides to a considerable extent. In the sea, seasonal variations of these parameters were less marked, and the effect of tides was not significant. Salinity and temperature values in the estuary and in the sea were maximum during the pre-monsoon season in general. The suspended sediment load values were always higher in the estuary than in the sea and they were found to be maximum in the monsoon season. Currents in the estuary were controlled by tides as well as by the river flow, particularly in the monsoon season, whereas currents in the sea mostly followed the general circulation pattern. Extinction coefficient values were higher in the monsoon season both in the estuary and in the sea due to increase in the particulate matter from inland drainage. 相似文献
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大姚地热动态特征分析 总被引：3，自引：1，他引：3
通过大姚高精度水温观测井水地质、井孔条件的分析，震例观测资料、实验观测数据的处理，以及井水水质分析结果，表明大姚水温周期性变化的突出位置是井深75m左右，根本原因是该地层石膏脉稳定释热，含水层热水与井内冷水混合过程中，在通道内形成钙盐类沉淀物（如CaSO4CaCO3），堵塞对流通道，含水层内外压差突破被阻塞通道，热水反复侵入井内，便形成水温周期性变化。地震的孕育、发生和调整过程，由于应力场作用，产生附加地热场，水温基值发生变化，周期畸变或消失，这种附加地热动态是可以恢复的。所以认为大姚地热动态是井区特殊地层地热信息的反映。 相似文献
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在1987年以来全球气温明显增高的同时，中国气温也显著增高，1997年达到了峰值，2006年又出现了次峰值.为搞清异常增暖对中国旱涝等灾害的发生可能带来的影响，本文重点统计分析了中国年平均气温对全球年平均气温的响应关系，并分析研究了1951～2006年期间中国月年平均气温的年际变化特征和汛期主要多雨带类型及发生严重洪涝区域之间的对应关系.结果发现：（1）3个中国年平均气温异常偏高但8月气温不高的来年汛期主要多雨带和严重洪涝区域都发生在淮河流域（3/3）；（2）5个年平均气温偏高且8月气温也明显偏高的来年汛期长江流域发生了大洪水和严重洪涝（5/5），特别是其中2个8月气温特高的来年（1954、1998年）汛期长江流域发生了特大洪水和严重洪涝（2/2）.对这个前兆强信号的发现和揭示，不但证明了全球和中国异常增暖对来年中国汛期水旱灾害的重大影响，也对准确预测中国汛期主要多雨带分布类型和江淮流域的大洪水和特大洪水有特别重要的应用价值. 相似文献
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讨论了强地震、孕震晚期阶段、震源区及附近介质的物理变化过程，证明了视电阻率变化最显著的方向与最大加载方向之间的正交关系，建立了真、视电阻率各向异性变化与裂隙率ν、骨架电阻率ρo、饱水裂隙电阻率ρf的本构关系，解释了视电阻率各向异性变化的原因.研究认为：在强地震孕震晚期阶段，在震源区及附近地壳近地表的较深部，介质微裂隙发育，其走向沿最大主压应力方位优势取向，低阻水充填微裂隙，导电通道连通，引起最大主压应力方向真电阻率变化最显著的真各向异性变化，从而产生垂直主压应力方向视电阻率变化最显著的视各向异性变化，低阻水在其物理过程中起了显著作用. 相似文献
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Spatial and seasonal patterns of flood change across Brazil 总被引：1，自引：1，他引：0
Brazil has some of the largest rivers in the world and has the second greatest flood loss potential among the emergent countries. Despite that, flood studies in this area are still scarce. In this paper, we used flood seasonality and trend analysis at the annual and seasonal scales in order to describe flood regimes and changes across the whole of Brazil in the period 1976–2015. We identified a strong seasonality of floods and a well-defined spatio-temporal pattern for flood occurrence. There are positive trends in the frequency and magnitude of floods in the North, South and parts of Southeast Brazil; and negative trends in the North-east and the remainder of Southeast Brazil. Trends in the magnitude (frequency) were predominant in the winter (summer). Overall, floods are becoming more frequent and intense in Brazilian regions characterized by wet conditions, and less frequent and intense in drier regions. 相似文献
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V. N. Mikhailov D. V. Magritsky V. I. Kravtsova M. V. Mikhailova M. V. Isupova 《Water Resources》2012,39(1):11-43
Regularities in the response of the mouths of major rivers, flowing into the Caspian Sea, to large-scale variations in its
level and river water runoff and sediment yield are considered. Changes in the morphological structure and hydrological regime
of the Volga, Terek, Sulak, Ural, and Kura mouths have been analyzed in both geological past and separately for three modern
periods: a considerable drop in Caspian Sea level before 1978, its abrupt rise in 1978–1995, and a relative stabilization
in the subsequent years. Specific features were identified in the hydrological-morphological processes in different mouths,
caused by the differences in river sediment yields, and the slopes of delta surface and mouth nearshore beds. Some theoretical
and methodological approaches were verified in the analysis and evaluation of the processes under consideration. The obtained
results of studies of the mouths of rivers flowing into the Caspian Sea can be regarded as examples and analogues in the assessment
of processes, which take place at the mouths of other Russian and world rivers at present and can take place in the future
under anticipated natural and anthropogenic variations in sea level and river runoff. 相似文献