通州地电阻率对唐山地区中强地震的映震能力分析     

王同利  崔博闻  李然  王丽红  胡毅涛  邢海林  李经山 《中国地震》2022,38(3):455-463

基于通州地表地电阻率在1976年唐山M7.8地震前有明显前兆异常以及通州新建井下小极距地电阻率在2020年古冶M5.1地震和2021年滦州M4.3地震前出现的异常变化,从台站周边构造环境、地震特征等方面进行对比分析,认为通州台地电阻率对唐山地区中强地震的中短期映震能力比较强。同时分析结果也显示在目前观测环境条件下,井下小极距地电阻率再现了通州台地电阻率对周边地区中强地震具有较强地映震能力。  相似文献   

青海玛多M7.4地震中剪力墙结构抗震性能初步分析     

张波  陈学良  邱利军  梁玲玉 《地球与行星物理论评》2022,53(1):112-118

本文选取2021年5月22日青海玛多县发生的M7.4地震的大武地震台实测加速度及课题组用经验格林函数法模拟的野马滩大桥处的加速度,并将二者的绝对加速度反应谱与中国地震动参数区划图(GB18306—2015)给出的“双参调整”设计反应谱进行对比分析,得到地震波观测值和模拟值对当地抗震设防结构的影响程度应视结构形式而定.然后将两条地震波分别输入到某11层剪力墙结构,用PKPM的SATWE模块进行多遇地震、设防地震下的线弹性分析,并用PUSH模块进行罕遇地震下的静力弹塑性分析.该剪力墙结构在两地区不同地震波作用时,均达到了“小震不坏,中震可修,大震不倒”的设防目标,其抗震性能目标达到C级.结论可为房屋建筑的抗震设防及震后应急响应提供很重要的参考.  相似文献   

发生短时强降雨的对流云合并作用分析     

刘裕禄  邱学兴  黄勇 《湖北气象》2015,34(1)

利用静止气象卫星、新一代多普勒天气雷达、地面、wrf数值模拟和LAPS再分析资料,对2013年6月30日皖南山区一次短时强降雨过程中的对流云合并现象进行了观测和分析。综合观测显示,这是一次由三个强弱不同的对流云先后发生合并的过程;强弱不同或强度相当的两对流云合并后的新对流云系统短时间内强度是增强的。分析认为,山区夏季对流云合并发生在水平垂直风切变及垂直涡度增大的湿斜压不稳定增强的环境中;对流云合并过程中伴有中气旋、地形涡等中γ系统形成,中气旋与地形涡系统内的强烈垂直运动导致低层形成辐合的垂直环流是山区短时强降雨触发机制。  相似文献   

Cross-axis sensitivity of accelerographs with pendulum like transducers—mathematical model and the inverse problem     

Maria I. Todorovska 《地震工程与结构动力学》1998,27(10):1031-1051

A mathematical model for a three-component accelerograph is presented that accounts for the effects of transducer misalignment and cross-axis sensitivity. The former refers to departures in the alignment of the transducer penduli (typically of the order of few degrees) from an ideal orthogonal system, and the latter to a transducer recording components of motion in directions other than its principal sensitivity axis. Transducer misalignment magnifies the effects of cross-axis sensitivity. These effects are significant only for large amplitude recordings (peak acceleration close to 1g), for example in the near-field of the 1994 Northridge, California, earthquake. The misalignment angles and the angular amplification constant can be determined by a static tilt test, performed in the field, and solving a generalized inverse problem. This paper presents an algorithm for solution of this inverse problem on a routine basis. Practical implementation of the algorithm and results for 76 instruments of the Los Angeles Strong Motion Array are presented in a separate paper. © 1998 John Wiley & Sons, Ltd.  相似文献   

Advanced sensitivity calibration of the Los Angeles strong motion array     

Maria I. Todorovska  Elena I. Novikova  Mihailo D. Trifunac  Sanja S. Ivanovi&#x; 《地震工程与结构动力学》1998,27(10):1053-1068

Results are presented of recent sensitivity calibration of 76 accelerographs (SMA-1) of the Los Angeles Strong Motion Array. These have pendulum-like transducers and optical recording system. One characteristic of their design is off-axis sensitivity, which is magnified by transducer misalignment. A new calibration procedure was applied, which considers off-axis sensitivity and measures the angles of misalignment (φ and ψ), as well as the incident angle of the light beam onto the film (θ₀). These are required (1) for accurate estimation of sensitivity, and (2) for proper instrument correction of recorded accelerograms which considers also cross-axis sensitivity and misalignment. These effects are important near large acceleration peaks (approaching and exceeding 1g), e.g. like the ones recorded near the source of the 1994 Northridge earthquake (M_L=6·4). This earthquake was recorded by 65 stations of the Los Angeles Strong Motion Array, at epicentral distances from 2 to 85 km. Histograms showing distribution of the misalignment angles, light beam incidence angle θ₀ (for unloaded position) and the transducer sensitivities are presented. These indicate that the misalignment angles are typically 1–1·5°, but may also be 3–4°. Angle θ₀ (usually neglected), is mostly between ±8°, but may reach ±12°. Assuming θ₀=0 leads to systematically smaller values of the measured sensitivity (e.g. by ∼3% for θ₀=8° and ∼4% for θ₀=12°). Comparison of the newly measured sensitivities with those measured prior to installation (in 1979/1980), s^old, shows that, in general, the new values are systematically smaller. The difference is typically within 5 per cent, but in some cases is as large as 10 per cent. Other principal sources of the observed differences and their mechanisms are discussed. Those include long-term changes in the transducers (e.g. change of stiffness, reflected in changes of the natural frequency) and differences in the calibration procedure (e.g. errors associated with manual reading film records with tilt test data, and with transducer and instrument housing misalignment). The presented results may be considered typical of similar strong motion arrays worldwide. © 1998 John Wiley & Sons, Ltd.  相似文献   

临界曲线附近的微引力透镜效应模拟          下载免费PDF全文

杨絮柳  陈雪纯  郑文雯  罗煜 《天文学报》2023,64(2):17-55

在光滑物质分布模型下,临界曲线是强引力透镜系统中像平面上一条放大率为无穷的线,而考虑少量离散质量的微透镜效应后,源平面上的放大率分布会出现复杂的结构,为暗物质成分的探测提供了一种有效途径.模拟临界曲线附近微透镜效应存在临界曲线上放大率无穷大和计算量巨大的困难.要达到所需的模拟精度,直接使用传统的光线追踪算法需要巨大的计算资源.为此发展了一个能实现海量计算的Graphics Processing Unit (GPU)并行方法来模拟临界曲线附近的微引力透镜效应.在型号为NVIDIA Tesla V100S PCIe 32 GB的GPU上,对于需要处理13000多个微透镜天体、发射1013量级光线的模拟,耗时在7000 s左右.在GPU并行的基础上,与直接的光线追踪算法相比,插值近似的引入使计算速度提升约两个数量级.利用该方法生成80个放大率分布图,并从中抽取800条光变曲线,进行了微焦散线数密度和峰值放大率的统计.  相似文献   

强台风“黑格比”暴雨洪涝特征及成因分析   总被引：3，自引：0，他引：3  

何慧  陆虹  欧艺 《热带地理》2009,29(5)

利用NCEP/NCAR再分析资料,分析0814号强台风"黑格比"引发华南西南部严重暴雨洪涝特征及其成因.结果显示:①2008年9月下旬副高强度偏强,位置偏北偏西,台风易受其南侧偏东气流引导而西行;②台风"黑格比"强度强,辐合上升运动强烈,触发强降雨;③南海夏季风增强和季风辐合带北抬,西南暖湿气流强盛,增强了辐合上升运动,并为台风降雨带来了源源不断的水汽,使降雨加强和持续;④除了气象因素外,地形对西行台风降雨量的显著增幅作用,是造成强台风"黑格比"暴雨洪涝的重要原因.  相似文献   

四川3次7级以上地震序列和余震分布特征的对比   总被引：1，自引：0，他引：1  

韩渭宾  蒋国芳 《四川地震》2009,(4):12-17

本文对比了汶川8．0级、炉霍7．6级和松潘、平武7．2级地震的地震序列类型、余震分布形状及其阶段性特征,并分析了这些特征异同与发震断裂带的特性关系。主要结论有：（1）扩大川滇其他震例对比统计认为,位于活动地块边界的大型活动断裂带上的强震往往是主震—余震型,双震或震群型地震往往不在块体边界大断裂带上。（2）强震余震区形状和余震随时间分布的阶段性受发震断裂带组合方式制约。  相似文献   

利用近场数字强震资料重新定位伽师、乌恰4次中强地震     

唐明帅  李锰 《内陆地震》2009,23(2):191-195

利用近场数字强震记录资料,采用和达法、台网地震编目程序(BLOC86)分别对新疆乌恰、伽师地区4次中强地震进行了重新定位.通过对定位结果的对比分析,结合新疆台网的部分实际工作,认为充分利用近场数字强震资料参与定位对于提高、总结和研究新疆部分地区地震定位精度是很有必要的.  相似文献   

Retrospection on the Conclusions of Earthquake Tendency Forecast before the Wenchuan M_S8.0 Earthquake     

Liu Jie  Guo Tieshuan  Yang Liming  Su Youjin  Li Gang 《中国地震研究》2009,23(2):119-133

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