汶川8．0级地震序列时空分布研究     

姜振泉  刘芙荣  徐瑞朋 《西安地质学院学报》2011,(4):428-433

基于四川防震减灾信息网以及中国地震台网中心、中国地震信息网、国家地震科学数据共享中心提供的汶川8．0级地震目录资料,对2008年S月12日至2010年3月1日共1613次3．0级及以上余震的地震序列进行了时空分布分析。结果表明：汶川8．0级地震的余震大致可分为7个阶段,主震后18天应列为大地震强余震发生的警戒时间;地震序列的b值为0．751,印证了在类型相同的情况下主震震级越大b值越高的观点;地震序列的P值为1．117,与全球地震衰减速率相当;汶川地震的余震分布主要沿龙门山断裂走向北东向扩展,且具有明显分区性,自南向北分为南、中、北3区段,南区为地震起始破裂段,地震后期余震则主要分布在北区;震源深度分布在10～40km,集中在10～20km,表明龙门山断裂主要发生在中上地壳,且震源深度由南向北呈现逐渐变浅的趋势;震源深度扩展,南区呈明显脉冲状,中区主要是依次由15、30、25km深度向深、浅层同时扩展,北区余震深度分布呈“乙”字型,最后稳定在15km左右。  相似文献   

祁连山夏季地形云综合探测试验   总被引：1，自引：0，他引：1  

郑国光  陈跃  陈添宇  陈乾  朱君鉴  李照荣 《地球科学进展》2011,26(10):1057-1070

2006年和2007年夏季在祁连山冷龙岭西段开展了地形云云量、云状、大气水汽、风场、雨滴谱和雨强等的综合探测试验,以分析祁连山地形云的特征。结果表明：①祁连山区夏季云量丰富,平均云量在6成以上。西南气流天气背景下总云量多达8成;②祁连山夏季无降水日大气水汽非常少,700 hPa以上层大气相对湿度大多在20%以下;③西南气流背景下祁连山南北侧山谷风的共同作用,气流昼间向山顶辐合,夜间向山谷辐散,当水汽条件充足时,极易抬升形成可以产生降水的地形云;④祁连山降水主要由小于1 mm的雨滴组成。  相似文献   

四川省青川县碾子村清岭沟泥石流特征及防灾对策     

张劲松  巨能攀  赵建军 《中国地质灾害与防治学报》2011,22(1):37-42

清岭沟位于四川省青川县碾子村五社,该区工程地质条件复杂。＂5.12＂地震后沟内出现大量崩塌落石和松散堆积物,为泥石流的爆发提供了充足的物源,2008年8月清岭沟地区发生连续强降雨,8月25日清岭沟爆发了泥石流。目前沟源及沟道两侧发育一处规模较大的潜在不稳定斜坡、三处规模较大的危岩体、一处形成于＂5.12＂地震期间的崩塌堆积物,一旦遭遇暴雨等不良地质作用这些潜在物源极易失稳,成为清岭沟泥石流的物源,使清岭沟再次发生泥石流灾害,威胁清岭沟下游村落及公路。通过野外对清岭沟进行地质调查、室内试验和动力学特征分析提出了UX—150型泥石流栅栏、拦砂坝、排导槽和桥涵改造的综合治理措施。  相似文献   

四川省汶川大地震成因及次生灾害     

宋洪伟  夏凡  龙文华  殷夏 《城市地质》2011,6(2):1-3,17

2008年5月12日14时28分,四川阿坝藏族羌族自治州境内的汶川县（31°N,103．4°E）发生了里氏8．0级浅源地震。震区范围长240km,宽30km,等震线呈长椭圆形,长轴为北东向,震中烈度约为10度,深度为12～19km。震区涉及四川绵阳市北川,德阳、汶川,成都、都江堰、广元、重庆以及甘肃、云南、陕西、河南等地区。除了吉林、黑龙江和新疆地区外,全国都有震感。在北川、汶川等多地区出现次生灾害。地震的发震构造是龙门山构遣带中央断裂带。  相似文献   

Dynamics of volcanic eruptions: Understanding electric signatures for activity monitoring     

《Comptes Rendus Geoscience》2015,347(3):112-123

Aside common methods as seismology, ground deformation, and geochemistry, electromagnetic and especially electric ones can efficiently be applied for imaging and monitoring active volcanoes and hydrothermal systems that most often control the initial eruptive phase. Surveys and mappings image ground fluids flow, faults systems, and structural interfaces with anomalies up to several hundred of mV. Reiteration of surveys highlights time and spatial evolution. Continuous networks must extend surveys when the activity becomes stronger. Resolution in the data can reach a few microvolts as compared to the tens of millivolts for surveys. Observations made on several volcanoes definitively show that electric signals, up to some tens of millivolts, may appear some hours to a few weeks before ground deformation and seismicity, and are related to some extent to the location of the future activity. These transient signals may have a relationship with those recorded aboard satellites. Both of them appear during the transition period between the “fatigue” and the “dynamical” stages, which announces accelerating and irreversible processes.  相似文献   

2008年汶川地震(Ms8.0)非对称同震破碎带的确定:来自WFSD-1随钻流体的证据          下载免费PDF全文

龚正 李海兵劳昌玲  唐力君罗立强李成龙  云锟  张佳佳  王雷振 《中国地质》2015,(2):480-494

地震过程中相当可观的一部分能量消耗于裂隙的活化与形成,来自汶川地震断裂带科学钻探一号孔(WFSD-1)的随钻流体表明,地震新形成的裂隙对应有较强的流体异常,它们为流体的入侵提供了良好的通道。随钻流体呈非对称性分布于主滑移面的两侧,主要的流体异常带集中在主滑移带下方须家河组顶部120 m范围内,该带中气体的含量以及变动的频率明显高于上部相同的宽度范围以及下部沉积岩层,来自地球物理测井的资料同样显示这一带破碎严重并伴随有大量水的侵入,暗示汶川地震形成的裂隙具有非对称性分布的特征。这一特征可能同时受控于断裂上盘彭灌杂岩与下盘须家河组岩层的力学性质差异以及地震破裂过程中形成的非对称性应力分布。  相似文献   

Globalising knowledge networks: Universities,diaspora strategies,and academic intermediaries     

《Geoforum》2015

As diaspora strategies have become an integral aspect of national economic development strategies, so too have universities begun to formally identify and mobilise diasporic scientists, researchers and scholars in an effort to create global knowledge networks. This paper will identify this new role for diasporic academics. It begins by emphasising the increasing internationalisation of the academic labour market, arguing that an increasing number of researchers have multiple national affiliations and relationships. It shows how diasporic academics have become central to the creation of global knowledge networks. These knowledge networks derive from multiple sources including the institutional ambitions of universities who are seeking to expand their research remits in increasingly resource constrained environments, international and national funding bodies who are increasingly focused on research ‘grand challenges’, and the aspirations of individual researchers for whom global networks are increasingly important to successful careers.  相似文献   

Seismic amplifications from offshore to shore     

《Applied Ocean Research》2015

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   

基于LiDAR和航空影像的地震灾害倒塌建筑物信息提取   总被引：1，自引：0，他引：1  

于海洋  程钢  张育民  卢小平 《国土资源遥感》2011,(3):77-81

地震灾害损失评估是震后展开救灾工作的重要环节.快速、准确地获取震后损毁建筑物信息能够为灾区减灾、救灾工作提供有效的支持.高分辨率航空遥感是灾害监测的重要技术手段,但其信息自动提取的精度受到一定的限制.近年来新出现的LiDAR技术能够提供地面目标的高程信息,可应用于复杂环境下倒塌建筑物信息的提取.研究中采用航空遥感数据和...  相似文献   

2010年1月12日海地 Mw7.0地震InSAR同震形变观测及同震滑动分布反演          下载免费PDF全文

薛莲  孙建宝  沈正康 《地震地质》2011,33(1):157-174

2010年1月12日GMT时间21时53分,在海地境内(72.57°W,18.44°N)发生了Mw7.0地震.文中利用干涉合成孔径雷达(InSAR)方法获得了覆盖整个震区的高精度形变观测资料,用以研究该地震的发震机理.采用ALOs PALSAR数据,分析了轨道、大气等误差源对干涉信号的影响,最终获得了雷达视线向(LOS...  相似文献