新疆南部构造区带与地震活动状态研究

以地震活动为主线并依据新疆地质构造运动、地壳缩短速率、断裂活动、局部应力场及历史强地震活动特征等的研究,将新疆南部地区初步划分为南天山东段、柯坪块体、喀什—乌恰交汇区及西昆仑地震带4个地震构造区带。利用新疆1900年以来的地震记录,在不同强度地震记录完整性分析的基础上,通过计算上述各构造区带年应变能释放均值、折合震级、不同震级下限的地震年发生率、b值和应变加速释放模型参数m值等参数,对各构造区带中地震活动状态进行了定量分析,进而提取了各构造区带地震活动状态的特征指标,为地震趋势分析和判定提供了定量的依据。     

新疆及邻区地震构造图简介

This paper briefly introduces the Seismotectonic Map of Xinjiang and its neighborhood in the scale of 1∶2500000.The map is amended,supplemented and expanded based of the newly compiled Seismotectonic Map of Xinjiang in scale 1∶1000000.The base map of this seismotectonic map is the geologic map of western China and its neighborhood compiled by Li Tingdong.The abundant new materials from related research,referential literatures and the analyses on remote sensing data were used in the compiling work.A database and relevant documents are built for nearly 300 active faults and 150 active folds.The basic information of the major active faults,especially those near the border areas in this map are introduced in this paper.     

新疆北部构造区带地震活动状态分析

在对新疆北部地区地质构造、构造运动强度、历史强地震活动特征、地壳缩短速率以及局部应力场特征综合研究的基础上,将新疆北部地区划分为阿尔泰地震带、乌鲁木齐、北天山西段、中天山和东天山5个地震构造区带.通过计算上述各构造区带年应变能释放均值、折合震级、不同震级下限的地震年发生率、b值和应变加速释放模型参数m值等参数,对各构造区带中地震活动状态进行了定量分析,进而提取了各构造区带地震活动状态的特征指标,为地震趋势分析和判定提供了定量的依据.     

新疆巴楚和塔什库尔干地震台下方地壳结构研究

Using the teleseismic waveform data recorded by the seismic station Bachu( hereafter referred to as station BCH) i n the Tarim Basin and the seismic station Taxkorgan(h ereafter referred to as station TAG) i n the west Kunlun Mountains for years,we applied the receiver function H-κ stacking method to study the crustal structure beneath stations BCH and TAG. The results showed that there are obvious differences in the crustal thickness beneath stations BCH and TAG,and the regional crustal thickness and terrain have a very good corresponding relationship. There are high crustal average V P/ V S values beneath the two stations. The crustal thickness is 44 km,and the crustal average wave velocity ratio is 1. 849 beneath station BCH. There is a sharp discontinuity in the middle of the crust beneath station BCH at a depth of 21 km. There is a low average P wave velocity and low V P/ V S from the surface to the discontinuity beneath station BCH.The depth of the discontinuity is consistent with the lower interface of the focal depth from accurate location in the Jiashi earthquake source area adjacent to station BCH; and may be the crustal brittle-ductile conversion boundary. The crustal thickness is 69 km,and the crustal average wave velocity ratio is 1. 847 beneath station TAG,a thicker crust and high V P/ V S may indicate that materials in the lower crustal are prone to plastic flow,which is responsible for the thickening of the crust.     

考虑地震构造背景的地震活动性参数光滑方法在地震危险性概率评价中的应用

In this study, the North China seismic region was selected as the study area, and evaluation of seismic hazard using the spatial smoothing seismicity model was performed. Firstly, the study area is divided into grids, and some parameters (e.g. b-value, M0, Mu, azimuth and M-L relationship) for each seismotectonic model were assigned. Secondly, using elliptical smoothing based on a seismotectonic background model, the statistical earthquake incidence rate in each grid is successively calculated. Lastly, the relevant ground motion attenuation relationship is chosen to assess seismic hazard of general sites. The maps for the distribution of horizontal peak ground acceleration with 10% probability of exceedance in 50 years were obtained by using the seismic hazard analysis method based on grid source. This seismicity model simplifies the methodology of probabilistic seismic hazard analysis, especially appropriate for those places where seismic tectonics is not yet clearly known. This method can provide valuable references for seismic zonation and seismic safety assessment for significant engineering projects.     

中国地震震源深度与强震活动状态研究

通过对中国绝大部分地区 1970年以来有仪器测定震源深度的地震资料进行详细分析 ,提出了“地震地热说”的假说并对分析结果作出解释 ,得出了一个关于中国强震活动大形势的全新观念 ,认为中国强震活动受到地壳深部 4个“热点”(吉林、新疆兴都库什、台湾和西藏日喀则等中深源震区 ) 70年代强震活动的牵引 ,完成了一个由地震活动高潮期 ( 1970 ?～ 1982 )、调整期 ( 1983～ 1992 )和消减期 ( 1993～ 1999?)所组成的地震链全过程。目前消减期尚未结束 ,但从 1999年 4月 8日吉林7 0级深震开始 ,新的一轮地震链过程可能已在酝酿之中     

新疆天山南部构造区不同时段小地震目录完整性分析

依据天山地区地质构造、运动强度和历史地震活动的差异性,将南部天山地区划分为南天山东段和南天山西段两个构造区.考虑到新疆台网建设的区域差异性和时间的阶段性,在对两个构造区不同震级下限地震频度时间特征分析的基础上,研究了各构造区不同时段的G-R关系和震级分布特征,并运用Z检验方法对各区不同时段小地震目录差异的显著性进行了分析,进而评估了两个构造区1970年以来不同时段的小地震目录完整性,为区域地震活动性研究中地震目录的合理运用提供参考依据.     

全球及主要构造带大震活动状态研究

在定性分析全球、环太平洋地震带、低纬度环球剪切带和大三角地区（我国大陆西部及邻区）地震活动特征的基础上,使用Morlet小波变换对其周期成分进行了定量计算,并应用Nowcasting方法对各研究区域当前大震风险进行定量评估.结果显示,①全球大震活动显著周期为48.6年,8.5级以上地震的潜在危险性评分为0.91.2004年开始的大震活跃时段可能仍将持续,发生8.5级以上地震危险性较大.②环太平洋地震带地震活动显著周期为48.6年,其大震活动起伏特征与全球大体一致,8.5级以上地震的潜在危险性评分为0.91.2010年开始的8.5级以上地震活跃时段持续时间尚短,发生8.5级以上地震的危险性较大.③低纬度环球剪切带地震活动显著周期为33.1年,反映了该区8.0级以上地震的起伏活动,8.0级以上地震的潜在危险性评分为0.46.2004年开始的活跃时段可能趋于结束,未来10年左右该区发生8.0级以上地震的可能性较小.④大三角地区地震活动显著周期为23.4年,发生7.8级以上地震的潜在危险性评分为0.72.2001年以来该区7.8级以上地震活跃,其活动状态与20世纪前50年类似.23.4年的周期成分反映了20世纪前50年7.8级以上地震活动韵律特征.2015年兴都库什7.8级地震后,该区可能进入了7.8级以上地震相对平静时段,该时段可能持续7~12年,未来几年存在发生7.8级以上地震的可能,但危险性较小.

     

新疆地震构造特征与烈度区划

在烈度区划工作中,区域背景分析是必要的。     

新疆地震构造带及其特征

本文根据地震活动特征,块体活动性质、地质构造特征、深部构造和震源力学,将新疆地震构划分为五个强震构造带。分别讨论了各带的地震活动和构造运动特征     

Seismotectonic Study on the West Part of the Interaction Zone Between Southern Tianshan and Northern Tarim

The interaction zone between southern Tianshan and northern Tarim is located at the northeast side of Pamir. It is a region with high seismicity. We constructed a seismotectonic model for the west part of this zone from geological profiles, deep crust seismic detection and earthquake focal mechanisms data. Based on the synthesized geological features, deep crust structure, and earthquake focal mechanisms, we think that the main regional tectonic feature is that the Tianshan tecto-lithostratigraphic unit overthrusts on the Tarim block. The Tianshan tectonic system includes the Maidan fault and thrust sheets in front of the fault; The Tarim tectonic system includes the underground northern Tarim margin fault, conjugate faults in basement and overthrust fault in shallow. The northern Tarim margin fault is a high angle fault deep in the Tarim crust, adjusting different trending deformation between Tianshan and Tarim. It is a major active fault that can generate large earthquakes. The other faults, such as the Tianshan overthrust system and the Tarim basement faults in this area may generate moderately strong earthquakes with different styles.     

龙门山和成都地震构造区的划分

新编制的地震动参数区划图采用了潜在震源区三级划分方案,以体现背景地震活动空间分布的不均匀性,并在地震构造区内归纳出统一的地震构造模型。本文根据西南地区潜在震源区三级划分的成果,分析了龙门山地震统计区内的龙门山和成都地震构造区的基本特征,历史地震活动强度及频度,主要活动构造的构造变形样式,建立了地震构造区的发震构造模型,确定了构造区的本地地震及划分构造源的地震构造标志。同时,提出了确定背景源空间分布函数的简单方法。     

Study on Uncertainties of Seismicity Parameters b and v4 in Seismic Statistical Zones

For several seismic statistical zones in North China,the key factors causing uncertainties in the important seismicity parameters b and ν_4 and the features of their uncertainties are discussed in this paper.The magnitude of uncertainty is also analyzed.It can be seen that the key influencing factors are statistical period,methods of processing statistical samples,lower limit magnitude and the annual average occurrence ratio of large earthquakes.The variation ranges of b and ν_4 in the Tancheng-Lujiang zone are as high as 0.2 and 1.4 respectively,which are similar to those in the Fenwei zone.They are much smaller however in the Hebei zone because of its sufficient statistical samples.     

大凉山断裂带与安宁河-则木河断裂带的地震活动性分析

通过对比分析,研究了大凉山断裂带和安宁河-则木河断裂带的地震活动性。认为在历史上安宁河-则木河断裂带的地震活动无论是频次还是强度都高于大凉山断裂带,这与活断层及古地震研究的结论是一致的。而且,地震活动性分段比较的结果显示,普格附近的空段2和冕宁附近的空段1发生强震的可能性最大,其次为西昌钝角交汇区．另外,需要注意强震前先发生中强震的可能性。     

Preliminary Study on Two Newly-Generated Seismotectonic Zones in North and Southwest China

In previous seismotectonic studies,the emphasis was placed on the inherited active fault zones.In the recent tectonic stage that essentially keeps in step with the current regional geologic environment and the stress field,however,there are also some newly generated fault zones.By studying the seismicity in North and Southwest China,it has been known that the NE-trending Tangshan-Hejian-Cixian and NW-trending Tengchong-Gengma-Lancang seismic zones are just two newly generated fault zones.As distinguished from the inherited fault zones,they are called the newly generated seismotectonic zones.This paper deals with the existence of these two seismogenic zones from their seismicity and geological structures,gives a preliminary analysis of their characteristics,and shows their significance.     

新疆强震前地震活动增强研究

系统研究了1970～2002年新疆天山30次中强震前地震增强现象,发现较大地震发生前中等地震的增强现象较为普遍;南北天山地震带增强区与后续主震震中相关性较好;除北天山地震带外,仅以地震增强现象作为地震中短期预测指标准确率太低;以增强发生后是否有平静现象发生作为确定短临异常的标准,预报效率可以提高。     

山西离石断裂带地震活动与地形变观测

对离石断裂带的地震活动特征进行了研究 ,认为离石地震台定点形变 (水平摆倾斜 )是地震异常信息传递的放大器 ,是山西地震活动的窗口 ,对山西地震带的地震监视预报有重要的意义。