利用水准测量数据分析芦山M_S7.0地震前龙门山断裂带南段应变积累     

宋成科  李腊月  孟庆筱  郑宇  管见  夏峰  周海涛  李进武 《地震研究》2015,38(2):237-241,333

利用2010年和2013年两期一等水准测量数据分析了龙门山断裂带南段芦山MS7.0地震前的应变积累。结果表明:(1)汶川地震的发生明显加速了该区域应变积累的过程,龙门山断裂带南段主要断层区域垂直形变速率为6~9 mm/a,表明汶川地震的发生加速了此次芦山地震的孕育过程;靠近鲜水河断裂带区域垂直形变速率为1~5 mm/a,低于汶川地震前的隆升速度。(2)芦山地震并未释放该区域长期积累的应变能,龙门山断裂带南段仍然具有发生破坏性地震的可能。  相似文献   

2013年甘肃岷县-漳县6.6级地震烈度异常点分布及成因     

陈正位  土登次仁  闫小兵 《中国地震》2015,31(2):338-343

2013年7月22日甘肃岷县-漳县Ms6.6地震发生在临潭-宕昌断裂的东段,遥感和DEM研究表明,该断裂东段在晚第四纪以来仍有活动,自岷县至宕昌,断裂由左旋走滑兼具逆冲性质转为以左旋走滑性质为主。现场烈度和灾害调查发现,Ⅶ度区内形成Ⅷ度的异常点,在Ⅵ度区内形成Ⅶ度的异常点,这些异常点分布在沿断裂带附近约2km的范围内,主要分布在断层的上盘。进一步研究表明,由于临潭-宕昌断裂在岷县以南以走滑运动为主,强震动主要沿断裂传播,同时由于断裂活动形成软弱地基,强震动引起地基失效造成灾害,形成了烈度异常点。  相似文献   

2012年6月24日宁蒗—盐源M_S5.7地震序列M_L≥3.5余震震源机制解     

杨军  李春海  陈佳  高琼  邓嘉美 《地震地磁观测与研究》2015,(3):21-26

针对2012年6月24日宁蒗—盐源MS 5.7地震序列,基于云南地震台网及部分四川地震台网宽频带数据,采用CAP方法反演该序列主震及ML≥3.5余震的震源机制解。结果显示:主震主应力方位角为148°,俯角58°,节面Ⅰ走向:179°、倾角55°、滑动角-43°;节面Ⅱ走向:297°、倾角26°、滑动角-136°,矩心深度4 km,矩震级5.36,表现为正断层兼走滑型地震,判定节面Ⅱ为其发震断层面,永宁断裂为其发震构造。  相似文献   

芦山7.0级地震区域地震活动能量场分析     

罗国富  马小军  马禾青  杨明芝 《东北地震研究》2015,(1)

运用随机函数理论,系统研究2013年芦山7.0级地震前区域地震活动能量场的时空特征。结果表明,四川芦山7.0级地震前能量场的前2个主要特征值对应的典型能量场时间因子出现明显上升变化,可能是该次地震的中短期时间异常特征;而主要典型场的空间等值线形成局部能量高值异常危险区,该区域可能是芦山7.0级地震的中短期空间异常特征。  相似文献   

利用两次新疆于田M_S7.3地震对 图像信息方法可预测性的检验          下载免费PDF全文

夏彩韵  张永仙  张小涛  吴永加 《地震学报》2015,37(2):312-322

以青藏构造块体为研究区域, 采用以往利用图像信息方法预测M7.0地震得到的较好的计算参数(网格尺度为1平方度, 预测时间窗口为8年), 系统计算了青藏构造块体1993年以来的“地震热点”图像, 特别研究了两次于田M_S7.3地震前后的图像信息演化过程, 并通过ROC方法和R值评分方法检验, 对图像信息方法在该地区的预测效能进行评价. 结果表明: ① 2008年3月21日于田M_S7.3地震和2014年2月12日于田M_S7.3地震均发生在地震热点上, 且发生在平均发震概率随时间变化的峰值点年份. ② 在回溯性检验的时间段内青藏构造块体共发生9次M≥7.0地震, 其中6次地震前震中附近均有稳定的地震热点出现, 包括两次于田M_S7.3地震. 1996年喀喇昆仑山口M_S7.1地震及2008年汶川M_S8.0地震只在个别预测时间窗内出现地震热点, 并没有出现稳定的地震热点演化过程, 而1996年丽江地震发生前震中附近则没有出现地震热点. 该结果与前人研究结果存在差异, 值得进一步研究. ③ ROC检验和R值评分结果均显示图像信息方法在本文采用的模型参数下对大地震具有较好的中长期预测效果. 本文还根据目前存在的地震热点给出了青藏高原块体2014年以后M7.0地震发生概率高的3个可能地区.   相似文献   

comprehensive study on the changing process of focal mechanisms of the 2014 huoshan m_s4.3 earthquake sequence     

NI Hong-yu  LIU Ze-min  HONG De-quan  WANG Xiao-li  ZHAO Peng 《地震地质》2015,37(4):1004-1019

In this paper, the focal mechanisms of Huoshan M_S4.3 earthquake sequence since October 2013 are calculated with the method developed recently by Snoke, which combines the use of first motion of P, SV and SH waves and their amplitude ratios(referred to as Snoke method). We estimate the difference(also referred to consistency parameter θ)between the stress axis direction of focal mechanism solution and the mean stress tensor on one hand, and get the relative changes of focal mechanisms rather than the focal mechanisms themselves on the other hand, by using methods of correlation coefficient of body-wave spectral amplitudes, first motions and amplitude ratios of vertical P wave of single station, as limited by the network layout and density of observation points, focal mechanism solutions of small earthquakes are not easy to obtain. We studied the changing process of focal mechanisms of Huoshan M_S4.3 earthquake sequence since October 2013 with many methods such as consistency parameter, correlation coefficient of body-wave spectral amplitudes, first motion and amplitude ratio of vertical P wave of single station, to determine the type of the sequence. The result shows that: before Huoshan M_S4.3 earthquake of April 20, 2014, the consistency parameter of the earthquake sequence was lower than the mean for a long period, correlation coefficient of body-wave spectral amplitudes was always at high values(about 0.9), odds ratio of first motions of vertical P wave of single station near the epicenter, defined as the ratio of predominant number to contrast number of first motions, was up to 13.8 at station SJH, 3.8 at BZY and 3.6 at LNA, respectively; first motions of vertical P wave of single station showed an obvious predominant distribution as a whole, and the amplitude ratios of vertical P were consistent, which suggests that before Huoshan M_S4.3 earthquake, focal mechanisms were consistent, so the earthquake sequence before Huoshan M_S4.3 earthquake is the foreshock sequence. After Huoshan M_S4.3 earthquake, correlation coefficient of body-wave spectral amplitudes was lower(about 0.6), first motions and amplitude ratios of vertical P wave of single station were in disorder, which suggest that the focal mechanisms are inconsistent after the Huoshan M_S4.3 earthquake, so the earthquake sequence after Huoshan M_S4.3 earthquake is the aftershock sequence, and subsequent larger earthquakes are not likely to occur. The focal mechanisms in Huoshan region during the period of Huoshan M_S4.3 earthquake experienced a process from scattering to convergency and to scattering again.  相似文献   

preliminary discussion on horizontal gravity gradient and its application to seismic gravity precursor research     

ZHAO Yun-feng  ZHU Yi-qing  LIU Fang 《地震地质》2015,37(4):1020-1029

In this paper, according to the synthetic gravity anomaly of a horizontally infinite cylindrical geologic body, gravity gradient in horizontal direction was calculated by potential field discrete cosine transformation in frequency domain. In the calculation, the minimum curvature method was used to extend edge lines. We found that the gravity gradient field from the potential field transformation was dependable by comparison with synthetic gravity gradient, except the data in the edges. Then, the accumulative horizontal gravity gradients before Lushan M_S7.0 earthquake were calculated for the accumulative gravity anomaly from September 2010 to October 2012. In the north-south direction, gravity gradient in Daofu-Kangding-Shimian and Markang-Lixian-Lushan exhibited a positive high value, and the strike of the high value zone was in line with the strike of Xianshuihe Faults and Markang Faults. In the east-west direction, high value zone was not as obvious as that in the north-south direction. Gravity gradients in the direction along and vertical to the strike of Longmenshan Faults were calculated by the definition of directional derivative. In the along-strike direction, high gravity gradient values appeared in Markang-Lixian areas along Markang Faults and Daofu-Kangding-Shimian areas along Xianshuihe Faults, and extremum appeared in Kangding-Shimian and the area nearby Lixian. In the direction vertical to the strike of Longmenshan fault zone, high gravity gradient values appeared in Lixian-Lushan-Kangding-Shimian areas, and the extremum appeared in the area nearby Kangding. The results indicate that gravity gradient in the direction along and vertical to the strike of faults can better show the relative gravity change on the two sides of faults. Lushan M_S7.0 earthquake is located at the transition zone between the two high value zones of gravity gradient. The total horizontal gravity gradient shows that the location and strike of the high value zone are basically consistent with regional faults, and the extremums of total horizontal gravity gradient appeared nearby Lixian, Kangding and Shimian.  相似文献   

基于粘弹库仑应力变化的后续最大地震震级估计及2008、2014年于田2次7.3级地震之间关系的讨论     

陈亚男  蒋海昆 《中国地震》2015,31(1):11-26

在前人关于于田地区地壳水平分层模型研究的基础上,结合于田台GPS连续观测资料粗略确定各层的粘滞系数。基于粘弹水平分层模型,分别计算了2008、2014年2次于田7.3级地震的粘弹同震库仑应力变化。基于粘弹库仑应力变化,采用"直接"余震频次的计算方法,得到了区域范围内与主震同震库仑应力变化直接相关的理论地震频次。提出了基于理论与实际地震频次对比以及理论与实际地震频次-距离衰减曲线拟合残差对比估计与主震同震库仑应力变化直接相关的后续最大地震震级的方法。不同方法的计算结果显示,与2008年于田7.3级地震同震库仑应力变化直接相关的最大后续地震震级为MS7.2~7.5,而2014年于田7.3级地震的最大后续震级估计为MS6.3。前者与2014年于田地震7.3的震级非常接近。由于震级相同、空间距离较近、时间间隔较短、区域外力作用相同、2次地震构造关联性较强且具有较明确的应力相互作用等,因而认为2008、2014年2次7.3级地震构成一对广义的双震型地震,这与该区域以往序列类型特点相吻合。对震级下限及G-R关系b值对结果的影响进行了初步讨论,结果显示,当粘弹同震库仑应力变化确定之后,震级下限对后续最大地震震级估计影响不大,但G-R关系b值对结果有较大影响。  相似文献   

2013年左贡-芒康M_S6.1地震序列震源机制变化过程研究     

何畅  朱航 《中国地震》2015,31(2):227-234

2013年8月12日西藏昌都地区左贡县、芒康县交界发生6.1级地震,地震序列为前-主-余型,在主震发生前9h内发生了7次ML≥2.0中小地震,最大震级为ML4.7。本文采用体波谱振幅相关系数方法,基于区域测震台网记录的数字地震波形资料研究左贡-芒康6.1级地震序列震源机制变化过程。结果显示,主震前的中小地震相关系数较高,均值为0.86,表明其震源机制相似程度较高,是具有震兆意义的小震序列;余震的相关系数较低,表明震源机制相似程度较低。  相似文献   

Detection of Pharmaceuticals and Personal Care Products in Agricultural Soils Receiving Biosolids Application     

Chenxi Wu  Alison L. Spongberg  Jason D. Witter  Min Fang  April Ames  Kevin P. Czajkowski 《洁净——土壤、空气、水》2010,38(3):230-237

Increasing research has suggested that biosolids generated from municipal wastewater treatment can be a major sink for many pharmaceuticals and personal care products (PPCPs) and their land application potentially introduces these contaminants into the terrestrial and aquatic environments. In this study, methods were developed for the analysis of 14 PPCPs in biosolids and soils using pressurized liquid extraction, solid phase extraction and liquid chromatography‐tandem mass spectrometry. Recoveries were over 50% for all analytes except diphenhydramine (?30%) in soils. Soil properties or type of biosolids showed minor effects on method recoveries. Estimated method limits of quantification (LOQ) range from 0.1–15 ng g^–1 for soil and 0.3–27 ng g^–1 for biosolids. A field study utilizing the methods revealed that other than carbamazepine‐10,11‐epoxide, all targeted compounds were detected in biosolids. Diphenhydramine, fluoxetine, triclosan and triclocarban were detected up to the μg g^–1 range with the highest concentration of 23 μg g^–1 for triclocarban. Seven of the PCCPs found in biosolids were also detected in agricultural soils amended with these biosolids and several (carbamazepine, diphenhydramine, and triclocarban) appeared to be persistent in soils. Triclocarban was also found most abundant in soils with the highest average concentration of 0.2 μg g^–1 while the rest of compounds were in the lower ng g^–1 range. Generally, the concentrations found on the fields were 2–3 degrees of magnitude lower than in the biosolids, which is likely to be due to dilution, degradation and leaching processes.  相似文献