地震活动断层分段与最大潜在地震

地震活动断层分段在核电工程选址及其地震危险性评价中具有重要的意义。着重讨论了几何段、地震段的含义,论述了如何进行地震活动断层分段和如何确定最大潜在地震,并以实例说明之     

郯庐断裂带下辽河—莱州湾段与潍坊—嘉山段地震构造和地震活动特 …

从地震构造和地震活动角度,对郯庐断裂带下辽河－莱州湾段和潍坊－嘉山段进行了对比,认为这两段的地震构造环境具有明显不同,地震活动明显属于不同模式。其中下辽河－莱州湾段属群集型地震活动类型;潍坊－嘉山段属特征型地震活动类型。对于下辽河－莱州湾段,未来应注意在新的活跃期或活跃幕到来时群集型强震、中强震的连续发生;对于潍坊－嘉山段,则应注意断层分段本身所控制的地震复发重现规律。     

断层蠕变的分维变化及其与地震之关系

据鲜水河断裂带连续蠕变观测资料,利用重建动力学方法,分别计算了各测点原始观测值、趋势形变值和消去趋势值后的残差值的关联维ｄ２。结果显示：蠕变观测时间序列不同成分的关联维变化,反映出不同的构造运动信息;关联维的大小与断层不同部位的活动有关,反映出断层的分段活动特性,各占类联维变化与测点周围的地震活动有关,降维变化是一种地震前兆现象。     

汶川8.0级地震序列活动的分段性研究

在汶川8.0级地震序列的跟踪研究中, 发现汶川地震序列具有明显的空间分段活动特点。 根据对汶川地震余震序列的部分测震学指标计算, 结果表明, 汶川地震序列可能是由以绵竹为界, 其西南段的汶川主-余震序列和绵竹北东段的北川－青川6级震群地震序列组成, 汶川地震可能具有龙门山活动构造的继承性运动特点。     

利用地震活动性分析对张北-尚义地震进行预测与震后反思

从地震活动性分析对张北－尚义地震所作的中长期预测进行总结与反思。首先通过张北－尚义地震所在的燕山－渤海北西向地震带的地震活动性分析,对该带作了分段,并确认了张家口段为未来中强震的危险段。第二步通过ＴＢＢ法计算确认了该段内２８号潜源为１～３ａ的危险区,该区靠近张北震中区,此次地震震中即在使用资料范围内。第三步,由对预报结果的反思,提出应加强中强地震构造背景的研究,特别要注意区域地震活动     

试论安宁河断裂带新活动的分段性与地震活动

本文根据近几年来对安宁河断裂带的野外调查资料,结合地震活动性、地壳形变、断层带中断层泥SEM特征分析,着重讨论了安宁河断裂带活动性的分段特征及其与地震活动的关系。资料表明,断裂带在晚更新世以来活动的强弱与地震活动在时间上和空间上分布的不均匀性有较好的一致性,即地震活动的强度、频度,严格受断裂带在晚更新世以来的活动强度、活动方式的制约。研究活动断层的活动分段性,对判定地震危险区及工程稳定性评价具有重要的科学意义和应用价值。     

从汞异常讨论阳江——从化断裂的活动性及对孕震的影响

根据区域重砂普查圈定的辰砂分散晕和跨断层剖面壤中气汞测量结果，联系已有地震资料，讨论了阳江－－从化断裂带的活动性及汞异常与地震活动的关系。认为：沿断裂 带群集的汞民中以作为活动断裂的判别标志之一；汞沿断裂裂隙向上运移系促使断裂活动的动力因素之一；汞异常段之间的相对低值区或其外侧系地震活动的主要场所。     

活断层分段及其地震危险性评价

本文论述了活断层分段中的一些基本概念和主要的边界标志。提出分段的基本原则是：以断裂的不连续性为依据，以地震危险性评价为目的，划分断层段。文中提出了９条分段依据和３９个具体标志。认为地震危险性评价应坚持两条原则：①由定性到定量；②循序渐进，逐步缩小范围和时段。文中提出了利用活断层资料确定潜在地震危险区、估算震级和预测发展时间的方法，其中的一些模型是作者近年来的最新研究成果。认为利用活断层分段进行地震危险性评价具有一定的科学性和实用性，是中长期地震预测的重要研究内容之一。     

广义海原断裂带断层气地球化学特征与地震活动性关系对比研究

根据广义海原断裂带断层气汞、氡浓度现场测量结果,对该断裂带不同段断层气浓度空间分布特征以及整体分布趋势进行深入分析,结合该区历史大震背景、现今地震活动性以及地震时空分布特征及b值空间扫描,深入探讨断层气分布特征与地震活动性之间的关系。研究表明,该断裂带断层气浓度强度分段性明显,与地震活动性存在较好的对应关系。研究结果可为该断裂地震危险性分析提供现今深部流体地球化学活动方面的证据,也为今后地震中长期预报提供重要基础资料。     

河北平原地震带的现今活动性分析

根据近41年的现代地震资料,利用地震活动性参数组合、b值空间分布、断裂带分段,并结合历史强震构造背景的综合分析方法,分析河北平原地震带各分段现今地震活动习性和地震危险性.研究结果表明：河北平原地震带存在7个具有不同现今活动习性的分段,其中,唐山—迁安段和东明—阳谷段处于低b值、高应力状态,属于大震后晚期余震活跃或断层震后调整运动结果;昌平—宝坻、天津—肃宁段、新河段、邯郸—磁县及汤西段断层面现今活动习性均处于相对低应力下的频繁或稀疏小震滑动.因此,河北平原地震带未来短期内发生强震的可能性较小.     

海原断层系的分形研究

本文根据Okubo等人测量圣安德烈斯断层系所用的复盖维数法,对海原断层系进行了分形测量,求出海原断层系的整体维数D_0=1.137,其景泰段D_0=1.109,海原段D_0=1.182。计算中未得到邵家水段和李使堡段的分维数。此外,文中还着重探讨了断层几何与地震活动性及其力学环境的关系,进一步证明了自相似断层的几何复杂性与地震活动密切相关,剪切断裂带具较低分维数(1.1—1.3),而在张性环境中形成的断裂体系具较高的分维数(1.5—1.6)。最后本文讨论了断层迹线图等因素对分形测量精度的影响。     

水系的分形特征与红河断裂带活动性关系初探

将分形几何学的原理和方法，应用于红河断裂带中南段断错水系的研究。发现断错水系的分维值变化可以反映当地新构造活动的的变化趋势，中段水系的分维值总体上高于南段，南段内部分维值有一定的变化，反映出断裂带的构造活动性由中段尾部向两头增强的趋势。     

祁连山与龙首山断层的分维特征

本文利用分维几何学方法对祁连山和龙首山断层进行了定量性研究。结果表明,分维数可以表征断层的不均匀性、不规则性和复杂性等,但是,与地震活动无明显的相关关系。分维数的大小与断层分枝数、断层迹线的展布面积有一定关系。     

台湾地区地震的空间关联维特征与构造环境研究

采用关联维方法对台湾地区地震活动的空间特征进行了研究。先利用 10 0a来台湾的地震目录计算各个地震区、带的关联维数 ,将地震空间分布的分形特征定量表达出来 ,然后综合分析地震空间分布的关联维数和孕震构造环境之间的关系 ,得出了以下结论 :1)台湾东、西部地震区由于地震属于不同的大地构造单元 ,因此关联维数有较大的差异 ;2 )在各地震区内部的各个地震带由于板块构造、地壳结构、活断层分布上的差异 ,而具有与其构造特征相对应的关联维数 ;3)各地震带内部的各个不同的部位又由于不同的构造应力场 ,而导致地震分布上出现不同的丛集性 ,表现为不同的关联维数。这些结论充分说明通过关联维分析所得到的地震活动的空间图像与地震活动所代表的不同地质构造背景有着良好的对应关系     

地貌参数揭示的三危山构造活动性差异及其原因探讨

三危山断裂位于青藏高原北缘,沿三危山西北麓展布,全长约175 km.根据其几何特征,可以将断裂分为三段:西段(西水沟—树沟子段)、中段(树沟子—十工口子段)和东段(十工口子—双塔段),其构造活动强度与地貌发育程度各段存在明显差异.根据断层陡坎测量和区域年代对比,三危山断裂西段垂直滑动速率约0.1 mm/a,中东段则较低...     

Paleoseismicity and Segmentation Along the Active Fault at the Northern Boundary of Huailai-Zhuolu Basin,Hebei Province

The northern boundary fault of Huailai-Zhuolu basin,Hebei Province,has a total length of 58 km and a general strike of NE.The geometry and feature of activity of the 5 segments of the fault greatly differ from each other.17 paleoseismic events have been recognized within 11 trenches excavated along the different segments of the fault.It is found that each segment is characterized by its distinct recurrence of paleoearthquakes.The recurrence intervals of strong earthquakes for each segment are 3500-7000 a for the shortest and 17,000-20,500 a for the longest.However,the recurrence interval of strong earthquakes for whole fault ranges between 750-8500 a.The boundary of the segments can be recognized as the junction,gap,bending,jog and salient of the fault.The length of the segment ranges between 7.5-14 km.     

景泰-天祝断裂单元与多重特征地震的危险性概率评估

基于景泰 -天祝断裂的大比例活动构造填图资料 ,建立了合理的破裂分段地质模型。在此基础上 ,采用地震危险性分析的“实时模型”并考虑断层段之间的相互作用 ,对景泰 -天祝断裂的大震危险性概率作了定量评估。所得结果认为 ,景泰 -天祝断裂的下次大震很可能是毛毛山与金强河两个单元破裂段的组合破裂 ,震级约MS7 5。未来 10 ,2 0 ,5 0 ,10 0a内最可能的发震概率分别是 14%、2 7%、5 6 %和 81%     

COULOMB STRESS EVOLUTION AND SEISMIC HAZARD ALONG THE EASTERN BOUNDARY OF THE SICHUAN-YUNNAN BLOCK

Using a more realistic model of multi-layered viscoelastic media, and considering the effects of the coseismic dislocation and the postseismic viscoelastic relaxation caused by the 34 great earthquakes occurring along the eastern boundary of the Sichuan-Yunnan block since 1480 and the interseismic stress accumulation caused by the tectonic loading generated by plate motions which were modeled by introducing "virtual negative displacements" along the major fault segment in the region under study, we calculated the evolution of the Coulomb stress change in each fault plane of 18 major fault segments along the eastern boundary caused by the coseismic, postseismic and interseismic effects. We studied the interactions of the Xianshuihe, Anninghe, Zemuhe and Xiaojiang fault zones on the eastern boundary of the Sichuan-Yunnan block. By evaluating if the previous earthquake could bring another earthquake closer to or farther from failure, we analyzed the interactions of the earthquakes which occurred in the different segments in the same fault zone, or in the different fault zones respectively. And further based on the calculation results of the Coulomb stress change on the fault planes, we analyzed the seismic hazard of each fault segment.The results show that the previous earthquake may trigger another earthquake which can occur in the same fault zone or in the different fault zone. And the calculation results on the evolution of the cumulative Coulomb stress change in the each fault segment show that, the Coulomb stress increases significantly in the middle section and the Moxi segment of the Xianshuihe fault zone, the Mianning-Xichang segment of the Anninghe fault zone, the Qiaojia-dongchuan segment and the Jianshui segment of the Xiaojiang fault zone, and the seismic hazard in these fault segments is worthy paying attention to.     

Fractal size and spatial distributions of fault zones: An investigation into the seismic Chelungpu Fault, Taiwan

Abstract   The fractality of fault zones of thickness T for the 248-m-long core from a borehole penetrating the northern segment of the seismic Chelungpu Fault, Taiwan, was analyzed. The frequency curve of T shows that the fractal dimension is normal when T is smaller than a characteristic thickness T _c, and it becomes abnormally large when T exceeds T _c. The fractal dimensions of size and spatial distributions of T increase as the mean distribution density of T increases, which is inconsistent with the evolution laws for ordinary brittle faults. This discrepancy implies that the thickening rate of T when T is more than T _c is not constant, but a decreasing function of fault displacement. The slow thickening rate is related to the elastohydrodynamic lubrication which was effective on the fault when T exceeds T _c. This slip instability mechanism can explain the large, fast and smooth slip on the northern segment of the Chelungpu Fault during the 1999 Chi-Chi earthquake.     

Preliminary Study on Cenozoic Group and Fault Activity in the Sea Area Near the Yangtze River Mouth

By shallow seismic prospecting, the Cenozoic Group in the sea area near the Yangtze Rver Mouth can be divided into five seismic sequences. They correspond to the Quaternary,Pliocene, Upper Miocene, Lower Miocene and Eocene respectively. The Quaternary System covers all the detecting area. The Tertiary System overlaps and thins out from NE to SW. The sedimentary basement mainly consists of volcanic rock (J3) and acidic rock (r35). Paleogene or Late Cretaceous basins are not found there. The faults that have been detected are all normal faults. They can be divided into three groups (NE, NW, near EW) by their trend. The NE and NW-trending faults are predominant, and agree with aeromagnetic anomaly. Their length and displacement are larger than that of the EW-trending faults. The activity of the NEtrending faults is different in different segments. The SW segment is a Quaternary fault, the middle segment is a Neogene fault, The NE is Paleogene. But the segment of the NW-trending fault is not obvious. The average vertical displacement rate is about 0.015mm/a.