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41.
巴基斯坦卡拉奇─海得拉巴区域地震危险性预测   总被引:1,自引:0,他引:1  
本文讨论了巴基斯坦的地震构造,潜在震源和历史与现代地震活动性,并在此基础上使用确定性和概率性两种方法计算了各发震断层50年内最大可能的地震在卡拉奇和海得拉巴两城市将引起的地面峰值加速度以及50年内超越概率为14%的等加速度区划图。  相似文献   
42.
热带太平洋地区SSTA和风应力场的海气耦合模态   总被引:13,自引:4,他引:13  
按国家气象局“八五”攻关力专家组提出的有关近海热带气候强度突变的标准,对1970-1991年在我国的近海发生强度突为的热带气旋进行了分类统计,发现如下气候特征:平均每年有8-9个热带气旋移到我国近海时发生强度突变,其中突然减弱的居多,占总个数的79.6%,突然增强的只占总个数的20.4%,突然增强只发和天5-10月,而突然减弱到5-12月均可发生;突然增强主要出现在浙闽沿海、南海中部,珠江口外西侧  相似文献   
43.
使用Bungum和Huseby方法对地方地震台网的监控能力和可靠性进行了分析。用震源位置的标准计算机码重新定位地震事件。由频率震级分布导出50%,90%和100%的累积监控能力阀值,对这些阀值23年内记录资料的监控能力水平作了估测。分析表明,在台网内发生的地震事件的台网100%监控能力水平为ML=1.7,从台网内固定实时震源对台网震源解精度作了分析。地震事件在台网内发生时,震中误差低于4km。最后讨论了地方地震台网连续运行期间影响监控能力的因素。  相似文献   
44.
2005年10月巴基斯坦MW7.6地震对余震的触发研究   总被引:6,自引:0,他引:6  
万永革  沈正康  尚丹 《中国地震》2006,22(3):277-286
本文研究分析了2005年10月8日巴基斯坦主震产生的库仑破裂应力变化对余震的影响。计算时考虑了以下因素:(1)断层泥区域的孔隙流体压力和介质弹性常数与周围介质中的不同;(2)地震震源区的构造应力场方向;(3)将震源区构造应力和主震破裂产生的应力叠加计算得到余震破裂机制。该研究考虑了多种因素,计算结果与余震的分布比较吻合。结果表明2005年10月8日巴基斯坦主震对大部分余震有触发作用。  相似文献   
45.
Tsunami deposits in the geological record   总被引:2,自引:0,他引:2  
A review is presented here of tsunami deposits in the geological record. It begins with a discussion of the relationships between the processes of tsunami generation and propagation and the sedimentary responses. This is followed by a consideration of the sedimentary processes associated with the passage of tsunami waves across coastlines. Attention is also given to the sedimentary processes associated with tsunami-triggered gravity backwash flows and comparisons are made with turbidity current action. We observe that despite sedimentary evidence for recent tsunamiites, geological research on ancient tsunamis has not identified stratigraphic units associated with onshore tsunami sedimentation. Equally, it is noted that nearly all published studies of sedimentary processes associated with modern tsunamis have not considered patterns of sediment transport and deposition in the offshore zone.  相似文献   
46.
2005年10月8日巴基斯坦7.8级地震热红外异常   总被引:4,自引:1,他引:4       下载免费PDF全文
收集了2005年巴基斯坦7.8级地震区Noaa17/AVHRR的2004-2005年的热红外遥感资料,并进行地表温度反演,得到了以震中为中心7°×7°范围的地表温度值。经热红外图像解译与构造关系对比分析,表明热红外解译图像与构造分布具有一致性。震源区地表温度时间序列显示:震前大约3个月内震源区存在明显的热红外异常。  相似文献   
47.
The use of logic trees in probabilistic seismic hazard analyses often involves a large number of branches that reflect the uncertainty in the selection of different models and in the selection of the parameter values of each model. The sensitivity analysis, as proposed by Rabinowitz and Steinberg [Rabinowitz, N., Steinberg, D.M., 1991. Seismic hazard sensitivity analysis: a multi-parameter approach. Bull. Seismol. Soc. Am. 81, 796–817], is an efficient tool that allows the construction of logic trees focusing attention on the parameters that have greater impact on the hazard.In this paper the sensitivity analysis is performed in order to identify the parameters that have the largest influence on the Western Liguria (North Western Italy) seismic hazard. The analysis is conducted for six strategic sites following the multi-parameter approach developed by Rabinowitz and Steinberg [Rabinowitz, N., Steinberg, D.M., 1991. Seismic hazard sensitivity analysis: a multi-parameter approach. Bull. Seismol. Soc. Am. 81, 796–817] and accounts for both mean hazard values and hazard values corresponding to different percentiles (e.g., 16%-ile and 84%-ile). The results are assessed in terms of the expected PGA with a 10% probability of exceedance in 50 years for rock conditions and account for both the contribution from specific source zones using the Cornell approach [Cornell, C.A., 1968. Engineering seismic risk analysis. Bull. Seismol. Soc. Am. 58, 1583–1606] and the spatially smoothed seismicity [Frankel, A., 1995. Mapping seismic hazard in the Central and Eastern United States. Seismol. Res. Lett. 66, 8–21]. The influence of different procedures for calculating seismic hazard, seismic catalogues (epicentral parameters), source zone models, frequency–magnitude parameters, maximum earthquake magnitude values and attenuation relationships is considered. As a result, the sensitivity analysis allows us to identify the parameters with higher influence on the hazard. Only these parameters should be subjected to careful discussion or further research in order to reduce the uncertainty in the hazard while those with little or no effect can be excluded from subsequent logic-tree-based seismic hazard analyses.  相似文献   
48.
The Cretaceous larger Foraminifera of Pakistan are restricted to the Upper Cretaceous belonging to the species of Orbitoides Lepidorbitoides, Omphalocyclus, and Siderolites. The species of these genera are quite distinct in comparison to other assemblages of the Tethys region. None of these species are identical in the Mediterranean or Caribbean regions, with the exception of few concordant species of Orbitoides recorded in the deep-sea cores of Bahama Island. The paleo-ecological factor is the most important consideration in paleogeographic distribution of the Upper Cretaceous larger Foraminifera.  相似文献   
49.
The objective of this study is to determine numerical estimations of seismic amplifications of waves traveling from offshore to shore considering the effect of sea floor configurations. According to the Boundary Element Method, boundary elements were used to irradiate waves and density force can be determined for each element. From this hypothesis, Huygens’ Principle is implemented since diffracted waves are constructed at the boundary from which they are radiated and this is equivalent to Somigliana's theorem. Application of boundary conditions leads to determine a system of integral equations of Fredholm type of second kind, which is solved by the Gaussian method. Various numerical models were analyzed, a first one was used to validate the proposed formulation and some other models were used to show various ideal sea floor configurations to estimate seismic amplifications. Once the formulation was validated, basic slope configurations were studied for estimating spectra of seismic amplifications for various sea floor materials. In general terms, compressional waves (P-waves) can produce seismic amplifications of the incident wave in the order of 2–5. On the other hand, distortional waves (S-waves) can produce amplifications up to 5.5 times the incident wave. A relevant finding is that the highest seismic amplifications due to an offshore earthquake are always located near the shore-line and not offshore despite the seafloor configuration.  相似文献   
50.
Drawing on a case study in Germany, this contribution explores the practical application of offshore aquaculture within offshore wind farms in view of the different stakeholders involved. Using a transdisciplinary research approach, an understanding of the rationalities and interests among the different involved stakeholder groups was explored. Offshore wind energy is high on the political agenda in Germany. The vast spatial requirements however inherit potential user conflicts with competing, and under current legislation excluded users such as fishermen. Solutions for combining sustainable uses of the same ocean space have thus seen increasing interest within the research community in Germany and in Europe over the past years. This paper was inspired by and presents the outcomes of a stakeholder analysis and in particular a stakeholder workshop. Central focus was placed on academics and private as well as public stakeholders engaged in current research efforts of combining offshore wind farms and aquaculture in the German North Sea. The paper identifies the overall acceptance of such a multi-use scenario in society, opportunities and constraints as perceived by the stakeholders, and key research gaps. The results confirm the assumption that there is a clear need, and also willingness on behalf of the policy makers and the research community, to find sustainable, resource- and space-efficient solutions for combined ocean use.  相似文献   
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