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1977年5月12日宁河6.6级地震的震中烈度较之震级相当的其他地震的震中烈度明显地偏低。为了阐明这种现象,由P波初动半周期及振幅求得了该区不同时期内的品质因数（Q值）及小震震源参数,并重新校对了这次地震以及1976年11月15日宁河6.9级地震的宏观及微观参数。分析结果表明:这次地震震中烈度异常低是因为1976年11月15日6.9级地震后,该区介质的品质因数大幅度下降,同时这个地震的震源深度比6.9级地震的震源深度约深5公里。品质因数和震源深度的综合效应可导致震中烈度降低近一度。 相似文献
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本文研究了量规函数、台站方位、台基以及不同测量方法对测定震级 ML 的影响.结果表明:1)得到了一个新的量规函数 R3（△）,它比原有的 R1（△）和 R2（△）更适合于我国西南地区:2)由于地震波辐射的方向性,处在不同方位的台站震级差可达0.3——0.5级.用 P 波与S 波的某种组合可消除一些方向性影响;3)基岩台基的校正值不大.某些较大的台基校正值可能是仪器放大倍数没测准的影响;4)除用 S 波的水平分量求震级外,S 波的垂直分量以及 P 波的水平分量和垂直分量乘以适当的倍数后,都可用来求震级 ML.求得的结果与常规方法的结果之间几乎没有什么差别. 相似文献
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富蕴地震断裂带南段主体走滑段多为正走滑断层，呈右行右阶或左阶排列。末端破裂段多不连续，呈弧形或左阶排列，部分沿支断层展布。 相似文献
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天山地区的高压自流水、高压油气藏及地热异常区的出露与天山地震带分布的一致性表明,孔隙水压异常高的动力条件可能成为触发浅源地震的重要机制。本文以丰富的震例为依据,认为天山地震带中强地震前地下流体出现两类异常:一类是应力应变能积累阶段的趋势性异常;一类是应力应变能预释放阶段的临震突发性异常。两类异常在形态上和时空分布上有完全不同的特征,它们显示出地震孕育过程中的两个完全不同的物理、化学过程。 相似文献
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LATE-QUATERNARY ACTIVITY OF THE YALAHE FAULT OF THE XIANSHUIHE FAULT ZONE,EASTERN MARGIN OF THE TIBET PLATEAU 
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下载免费PDF全文 LIANG Ming-jian CHEN Li-chun RAN Yong-kang LI Yan-bao WANG Dong GAO Shuai-po HAN Ming-ming ZENG Di 《地震地质》1979,42(2):513-525
Complex geometrical structures on strike-slip faults would likely affect fault behavior such as strain accumulation and distribution, seismic rupture process, etc. The Xianshuihe Fault has been considered to be a Holocene active strike-slip fault with a high horizontal slip rate along the eastern margin of the Tibetan plateau. During the past 300 years, the Xianshuihe Fault produced 8 earthquakes with magnitude≥7 along the whole fault and showed strong activities of large earthquakes. Taking the Huiyuansi Basin as a structure boundary, the northwestern and southeastern segments of the Xianshuihe Fault show different characteristics. The northwestern segment, consisting of the Luhuo, Daofu and Qianning sections, shows a left-stepping en echelon pattern by simple fault strands. However, the southeastern segment(Huiyuansi-Kangding segment)has a complex structure and is divided into three sub-faults: the Yalahe, Selaha and Zheduotang Faults. To the south of Kangding County, the Moxi segment of the Xianshuihe Fault shows a simple structure. The previous studies suggest that the three sub-faults(the Yalahe, Selaha and Zheduotang Faults of the Huiyuansi-Kangding segment)unevenly distribute the strain of the northwestern segment of the Xianshuihe Fault. However, the disagreement of the new activity of the Yalahe Fault limits the understanding of the strain distribution model of the Huiyuansi-Kangding segment. Most scholars believed that the Yalahe Fault is a Holocene active fault. However, Zhang et al.(2017)used low-temperature thermochronology to study the cooling history of the Gongga rock mass, and suggested that the Yalahe Fault is now inactive and the latest activity of the Xianshuihe Fault has moved westward over the Selaha Fault. The Yalahe Fault is the only segment of the Xianshuihe Fault that lacks records of the strong historical earthquakes. Moreover, the Yalahe Fault is located in the alpine valley area, and the previous traffic conditions were very bad. Thus, the previous research on fault activity of the fault relied mainly on the interpretation of remote sensing, and the uncertainty was relatively large. Through remote sensing and field investigation, we found the geological and geomorphological evidence for Holocene activity of the Yalahe Fault. Moreover, we found a well-preserved seismic surface rupture zone with a length of about 10km near the Yariacuo and the co-seismic offsets of the earthquake are about 2.5~3.5m. In addition, we also advance the new active fault track of the Yalahe Fault to Yala Town near Kangding County. In Wangmu and Yala Town, we found the geological evidence for the latest fault activity that the Holocene alluvial fans were dislocated by the fault. These evidences suggest that the Yalahe Fault is a Holocene active fault, and has the seismogenic tectonic condition to produce a large earthquake, just like the Selaha and Zheduotang Faults. These also provide seismic geological evidence for the strain distribution model of the Kangding-Huiyuansi segment of the Xianshuihe Fault. 相似文献
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1605年琼州地震,是迄今发生在我国海南岛地区仅有的一次大地震.对该次地震震害特征和发震构造的深入研究,将有助于正确评定该地区的地震危险性;对研究南海北部陆缘地带的地震特征和发震构造,具有重要意义. 本文作者在雷琼地区进行了详细的实地考察,发现了大批记载本次大震情景和震害状况的家谱、族谱和碑记;发现并证实了该次地震所造成的大规模陆陷成海的遗墟.本项研究结果认为,1605年琼州大地震的震中烈度达ⅩⅠ度;震级为7 1/2——8级;震中位于琼山县塔市附近(北纬20,东经110.5). 对震源区地质构造和地球物理场的研究结果表明,该次大地震的发震断裂为NEE走向的光村——铺前深断裂和NNW走向的塔市——演丰断裂(以前者为主);该次大地震是水平构造应力(主压应力轴方向为NWW300左右)和垂直构造应力共同作用的结果;垂直向构造应力在大震发生和造成大规模陆陷成海过程中起着主要作用. 重、磁等地球物理场特征研究结果还表明,1605年琼州大地震的发生,不是单纯地壳构造断裂的结果,而是深部地球物理场在此震源区的特殊构造部位,由于主要震源断裂两盘重力场特征不同的构造块体物质密度,即重力场源的差异,在重力均衡补偿调整的过程中,上地幔的隆起与拗陷的差异升降、岩浆物质的差异运动,以及热动力的差异运动的复合结果. 相似文献
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对日本兵库县南部地震震灾统计时程曲线的初步分析 总被引：4，自引：0，他引：4
本文作者制作了日本兵库县南部地震震灾统计时程曲线，归纳了该曲线的特点，并对此进行了相应的分析。同时，针对我国地震灾情调查和评估提出了一些意见。 相似文献
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新疆博格达山北麓山前断裂西段的断裂组成及其在全新世时期的活动 总被引：6，自引：2，他引：4
博格达山北麓山前断裂西段全长１４０ ｋｍ ,由５ 条雁列状排列的逆断裂组成。全新世时期,古牧地断裂的最新活动发生在６．８２±０．５４～４．８７±０．３９ Ｋａ Ｂ．Ｐ．之间;四工河口断裂切割Ⅱ级河流阶地,最新活动时间与古牧地断裂大体相同;泉泉子断裂切割Ⅰ级河流阶地,最新活动发生在３．７５±０．４１ Ｋａ Ｂ．Ｐ．;热水河断裂及东风牧场断裂由于缺乏断代年龄实测数据,无法对其最新活动时间作出判断,但是推断它们也是全新世活断裂 相似文献
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天山起源于古生代的陆-陆碰撞作用,又经历了中新生代的典型陆内造山过程,其深浅构造结构和活动性一直是众多学者关注的热点。文中通过多种地球物理探测和综合地质构造分析, 以地学断面形式对其深浅构造进行填图,揭示了天山中段复杂的深浅构造特色。结果表明:沿古生代的陆-陆碰撞缝合带两侧分别呈现出主要构造地质单元由老到新的对称性,并伴有相应深部结构的复杂性,反映了碰撞过程及后期的构造演化特点;天山中部的上地幔顶部存在厚近 10km、宽近 200km、几乎涵盖整个天山的低速高导层,可能是中新生代以来天山的陆内再造山作用引起的壳幔拆沉作用形成的残留下地壳 相似文献
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1.地裂缝的基本特征1977年8月—9月西安辛家庙铁炉庙一带相继发现地裂缝。铁炉庙地裂缝位于市东南郊渭河三级阶地内黄土塬前缘洼地的北侧,东起铁炉庙,经后村、小寨、西到吉样村,断续延伸约6.5公里,尤以铁炉庙地段最为发育。其总体走向为北70°东,倾角70—90°(一般为76°)。由数十条地裂缝组成裂缝带,宽度为8—20米,一般在10米左右。地裂所经之处,建筑物多被裂开。 相似文献
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THE TECTONIC ACTIVITY CHARACTERISTICS OF AWANCANG FAULT IN THE LATE QUATERNARY,THE SUB-STRAND OF THE EASTERN KUNLUN FAULT 下载免费PDF全文
下载免费PDF全文 It is well known that the slip rate of Kunlun Fault descends at the east segment, but little known about the Awancang Fault and its role in strain partitioning with Kunlun Fault. Whether the sub-strand(Awancang Fault) can rupture simultaneously with Kunlun Fault remains unknown. Based on field investigations, aerial-photo morphological analysis, topographic surveys and 14C dating of alluvial surfaces, we used displaced terrace risers to estimate geological slip rates along the Awancang Fault, which lies on the western margin of the Ruoergai Basin and the eastern edge of the Tibetan plateau, the results indicate that the slip rate is 3mm/a in the middle Holocene, similar to the reduced value of the Kunlun Fault. The fault consists of two segments with strike N50° W, located at distance about 16km, and converged to single stand to the SE direction. Our results demonstrate that the Awancang fault zone is predominantly left-lateral with a small amount of northeast-verging thrust component. The slip rates decrease sharply about 4mm/a from west to east between the intersection zone of the Awancang Fault and Kunlun Fault. Together with our previous trenching results on the Kunlun Fault, the comparison with slip rates at the Kunlun fault zone suggests that the Awancang fault zone has an important role in strain partitioning for east extension of Kunlun Fault in eastern Tibet. At the same time, the 15km long surface rupture zone of the southeast segment was found at the Awancang Fault. By dating the latest faulted geomorphologic surface, the last event may be since the 1766±54 Cal a BP. Through analysis of the trench, there are four paleoearthquake events identified recurring in situ on the Awancang Fault and the latest event is since (850±30)a BP. The slip rate of the Awancang Fault is almost equivalent to the descending value of the eastern part of the east Kunlun Fault, which can well explain the slip rate decreasing of the eastern part of the east Kunlun Fault(the Maqin-Maqu segment)and the characteristics of the structure dynamics of the eastern edge of the Tibet Plateau. The falling slip rate gradient of the eastern Kunlun Fault corresponds to the geometric characteristic. It is the Awancang Fault, the strand of the East Kunlun Fault that accommodates the strain distribution of the eastward extension of the east Kunlun Fault. This study is helpful to seismic hazard assessment and understanding the deformation mechanism in eastern Tibet. 相似文献
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塔里木盆地新疆喀什以西部分是西南天山和帕米尔两大对冲构造系统的会聚带,关于两者变形前缘和分界的确切位置存在不同认识.在乌恰县以南的玛依卡克盆地南缘,清晰可见属于帕米尔构造带、向N或NNE逆冲的帕米尔前缘逆冲推覆体(PFT).最近野外调查在盆地北部发现了西南天山前缘的最新变形带:向南逆冲的乌拉根背斜南翼断层.断层总体近E... 相似文献
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2008年汶川M_S8.0地震地表破裂变形定量分析——北川-映秀断裂地表破裂带 总被引：35，自引：14，他引：21
2008年汶川MS8.0地震在北川-映秀断裂产生了长达240km的同震地表破裂。通过详细的测量、基于测量标志与断裂变形的几何关系对数据的分析,给出了观测点的断裂同震地表变形的垂直位移、倾向水平缩短、走向滑动、断层上盘水平运动方向等参数。结果显示,断裂同震变形分布的空间变化很大,目前获得的最大水平位移位于虹口乡深溪沟,为4.98m,同时也是最大右旋走滑位移点,走滑量4.5m,而目前获得的最大垂直位移在其东北的支沟,为5.7~6.7m。NE向断裂水平位移多为1~2m,垂直位移多为3m左右,而小鱼洞-草坝分支断裂水平位移和垂直位移都更小,只有0.5~1.5m。擂鼓镇附近的数据则反映与断裂相关的巨型滑坡可能将重力变形叠加到构造变形中。由断层水平缩短和垂直位移计算的断层倾角表明,北川-映秀断裂是浅部陡倾的具有走滑分量的逆断层 相似文献
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小店子—茅埠段是沂沭断裂带安丘-莒县断裂的组成部分,北起莒县小店子东北,南至莒县茅埠以南,总体走向10°～20°,倾向NW或SE,倾角60°以上,长约30km。可细分为5小段,从北到南依次是小店子—齐家庄、源河、库山—西莲池、青峰岭和三庄—宅科小段。各小段之间为左阶或右阶斜列,平面上呈向北收敛、向南撒开的帚状。断裂在卫片和航片上都显示出清楚的线性影像,地貌上表现为清楚的基岩陡坎。根据野外所获得的天然和探槽剖面以及年龄样品测试结果,确定其最新活动时代为全新世早期,活动性质是以右旋走滑为主兼挤压逆断。距今约70ka以来,断裂的右旋位移量64～73m,位移速率0.91～1.04mm/a。距今约12ka以来,断裂的右旋位移量5.5～7.8m,位移速率0.46～0.65mm/a;垂直位移量2～3.8m,位移速率0.17～0.32mm/a 相似文献
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本文在简要地论述了台湾岛及其周围地区的地质构造、重力异常、地壳结构和地震活动等特征的基础上划分了地震构造带,对台湾岛上7级以上强震的发震构造条件作了初步讨论,最后用板块构造观点探讨了本区地震的构造成因 相似文献