汶川M_S8.0地震河谷地形对汉源县城高烈度异常的影响          下载免费PDF全文

李平  刘红帅  薄景山  李孝波  于晓辉 《地球物理学报》2016,59(1):174-184

汉源县城位于汶川M_S8.0特大地震六度区内唯一的八度异常区,为典型且罕见的远震高烈度异常区.汉源县城处于流沙河的河流阶地之上,河谷地形对地震震害有显著的影响.为定量分析河谷地形对汶川大地震汉源县高烈度异常的影响,基于汉源县城震害科学考察和场地勘察获取的资料,根据震害分布特征和流沙河谷地形的特点,选取1条实测得到的横切汉源县城并垂直流沙河河谷方向的典型剖面作为计算模型,以脉冲作为基底输入,采用有限差分方法研究了该剖面的场地放大效应,分析了地形对高烈度异常的影响.计算结果表明:汉源县城场地对地震动放大效应的显著频段是1.0~10Hz,且这一频段老县城场地的放大效应比新县城场地显著;汉源老县城场地对汶川M_S8.0地震主震的地震动有显著的放大效应,地表峰值加速度大大超过了抗震设计规范的规定值;汉源场地地形放大效应显著频段与汶川M_S8.0地震的能量集中频段基本吻合,汉源老县城建筑物的自振频率恰恰位于该频段,产生共振效应,从而造成更显著的放大效应,这也是汉源震害异常的主要原因之一.由此可见,河谷地形对地表地震动有重要的影响,在工程选址和抗震设计时应考虑其影响.  相似文献   

C-ATS地电仪常见故障分析及排除     

陈智群  黄晖  刘吉平  李敬  刘东辉 《华南地震》2015,35(1):119-123

对C-ATS地电仪系统构成、工作原理和特点进行了介绍,结合维护检修经验对C-ATS地电仪常见故障的原因进行了详细分析,对故障的排除方法进行阐述,检查维护仪器的方法经验,对其它地电台站有一定的参考意义。  相似文献   

河北及邻区平均波速比变化特征分析     

王亚茹  王想  宫猛  郭蕾  刘晓丹 《中国地震》2016,32(4):747-755

用和达法计算河北及邻区地震波速比并按照不同震级不同窗口作滑动平均。通过对唐山地区波速比变化特征与中强地震对应关系的定性分析,发现M_L≥1.5地震波速比曲线与M_L≥4.0的地震对应较好,提出异常指标进行定量统计得到该区波速比异常与地震的对应关系和预报效能;按照同样的思路对河北另外3个地区进行分析,发现各分区波速比异常既有共性特征也有差异。  相似文献   

宁波九龙湖火山岩非地热异常区地热资源勘查     

石晓今  秦莉红  邱京卫 《城市地质》2019,14(1):34-39

宁波地区属浙东南陆相火山岩区,地层在数千米深度内以侏罗系和白垩系的火山碎屑岩(凝灰质粉砂岩为主)及少量熔岩为主。这一套地层总体上孔隙不发育,渗透性极弱,岩石热导率低,属于非地热异常区。地质构造发展的长期地质历史造就了断裂和裂隙系统,该地区地热类型属隆起区断裂深循环型。九龙湖地区采用可控源音频大地电磁测深、氡气和热释汞综合测量及高精度重力等综合物探手段,以寻找孔隙度较高的地层或断裂构造带,对于寻找地热资源起到了很好的效果。分析研究区地表水和地热水的水文地球特征,运用地球化学温标预测地热水温度,表明地层深部可能还赋存有更高温度的热水。  相似文献   

安徽胡家碾地区井中地电异常现象探讨          下载免费PDF全文

王占孝  王显光 《山东国土资源》2012,28(3):32-34

以岩石电性特征差异为基础的电测井,在金属矿产、地下水资源勘探中,发挥着重要的作用。在视电阻率测井装置中,地井系统是较为常用装置形式。通过安徽省胡家碾地区地质背景和钻孔地层以及对井中电法测量资料的分析对比,探讨了井中地电异常产生的原因及与寻找地下水的关系,认为井中负视电阻率异常与井中正自然电位异常相对应时,通常是寻找地下水的有利地段。  相似文献   

模拟水氡异常判别   总被引：1，自引：0，他引：1  

廖丽霞 《内陆地震》2008,22(2):143-150

阐述了模拟水氡测值的影响因素,并以福州乌鸦嘴泉点为例阐述了模拟水氡异常的判识方法,为模拟水氡的异常判识提供了实例。对模拟水氡异常进行判别,充分了解水点的基本情况及所有影响因素,并了解这些影响因素对水氡的影响规律,在此基础上对干扰因素加以排除,同时用同一水点其他测项的同步变化特征来佐证该异常不是观测过程中人为及仪器因素造成的,最后进行区域背景场对比分析,再用同一区域其他水点同测项测值的同步变化情况加以佐证,以判断是否是该区域应力场所致。分析结果表明,乌鸦嘴泉出现水氡年动态畸变异常的成因在很大程度上可能是区域应力场发生变化所致。  相似文献   

Anomalies in Water Level Records in Yunnan Caused by the Great Indonesian Earthquakes and Their Significance     

Fu Hong  Wu Chengdong  Liu Qiang  Wang Shiqin  Chen Yan 《中国地震研究》2008,22(4):440-447

Two great earthquakes occurred in the sea northwest of Sumatra, Indonesia, on December 26, 2004 and March 29,2005. The observation of water levels in Yunnan yielded abundant information about the two earthquakes. This paper presents the water level response to the two earthquakes in Yunnan and makes a preliminary analysis. It is observed that the large earthquake- induced abnormal water level change could be better recorded by analog recording than by digital recording. The large earthquake-caused water level rise or decline may be attributed to the effect of seismic waves that change the stress in tectonic units, and is correlated with the geological structure where the well is located. The water level response mode in a well is totally the same for earthquakes occurring on the same fault and with the same fracture mode. The only difference is that the response amplitude increases with the growth of the earthquake magnitude.  相似文献   

Application on Anomaly Detection of Geoelectric Field Based on Deep Learning     

WEI Lei  AN Zhanghui  FAN Yingying  CHEN Quan  YUAN Lihu  HOU Zeyu 《中国地震研究》2020,34(3):358-377

The deep learning method has made nurnerials achievements regarding anomaly detection in the field of time series. We introduce the speech production model in the field of artificial intelligence, changing the convolution layer of the general convolution neural network to the residual element structure by adding identity mapping, and expanding the receptive domain of the model by using the dilated causal convolution. Based on the dilated causal convolution network and the method of log probability density function, the anomalous events are detected according to the anomaly scores. The validity of the method is verified by the simulation data, which is applied to the actual observed data on the observation staion of Pingliang geoeletric field in Gansu Province. The results show that one month before the Wenchuan M_S8.0, Lushan M_S7.0 and Minxian-Zhangxian M_S6.6 earthquakes, the daily cumulative error of log probability density of the predicted results in Pingliang Station suddenly decreases, which is consistent with the actual earthquake anomalies in a certain time range. After analyzing the combined factors including the spatial electromagnetic environment and the variation of micro fissures before the earthquake, we explain the possible causes of the anomalies in the geoelectric field of before the earthquake. The successful application of deep learning in observed data of the geoelectric field may behefit for improving the ultilization rate both the data and the efficiency of detection. Besides, it may provide technical support for more seismic research.  相似文献   

Spatial Correlation Anomalies of the Diurnal Variation of the Geomagnetic Vertical Component before the Yingjiang MS6.1 and Ludian MS6.5 Earthquakes     

Dai Yong  Feng Zhisheng  Yang Yanming  Gegen 《中国地震研究》2018,32(4):521-532

Significant anomalies were observed at the geomagnetic stations in the southwest region of China before the Yingjiang M_S6.1 earthquake and the Ludian M_S6.5 earthquake in 2014. We processed the geomagnetic vertical component diurnal variation data by the spatial correlation method. The results show that during the period from April 1 to May 20, 2014,there existed quasi-synchronous decrease changes in the coefficient curves between the five geomagnetic stations of Guiyang,Hechi,Nanshan,Muli,Yongning and Xinyi and Hongshan stations.Furthermore,there was a high gradient zone in the normalized correlation coefficient contour map with background values removed. The epicenters of the Yingjiang M_S6.1 earthquake and the Ludian M_S6.5 earthquake are located in the gradient zone or near the gradient zone.  相似文献   

2020年1月19日新疆伽师MS6.4地震前地震活动特征分析     

聂晓红  刘建明  向元  高荣  张琳琳 《内陆地震》2020,(1):10-19

简要介绍2020年伽师M S6.4地震周围地质构造背景,研究分析了M S6.4地震前新疆地区和柯坪块体地震活动状态、区域地震活动图像特征。结果表明:①本次地震前1~2年和震前半年,新疆境内中强和中小地震呈现“平静—成组活跃”或显著增强特征;②本次地震发生在柯坪块体M S≥6.0地震平静近15年的背景下,震前区域地震活动存在时间渐进的中短期异常特征,即震前2年,5级以上地震活动呈现NE向有序条带分布;震前1年南天山西段小震群累积月频度呈现“加速”活动特征;震前半年震区附近4级地震条带形成共扼分布特征;震前3个月震区附近出现地震窗超限异常;震前2个月震区附近地区视应力呈现显著高值异常;③震前地震活动具有较好的“长、中、短”期异常配套出现的特征。  相似文献