基于活动地块边界带的测震学参数Mf值对丽江地震的预测应用

地震构造是强震发生的必要基础,强震的孕育和发生与构造密切相关。强震的孕育和发生不仅与震中周围构造有关,而且与孕震区所在的整个构造带有关。这就表明整个构造带的地震活动性与未来强震都有关联。因此,在做测震学参数异常预测地震时,必须考虑整个构造带的地震活动。过去人们常以震中周围地区的地震活动资料来做测震学参数的异常分析,可能会丢失部分信息。文中以金沙江—红河边界带和地震学参量Mf值的结合为例,对基于活动地块边界带的测震学参数强震预测进行了探索,其结果对丽江地震预测效果很好,这对边界带的地震危险性判定有某种参考价值。     

2003年云南大姚两次强震破裂区重叠程度的研究

地震破裂后,破裂区应变能是否已经充分释放.能否在破裂面内再次发生震级接近的地震,是双主震研究的重要问题.通过对2003年云南大姚两个地震序列的双差定位,发现余震区扩展,但两余震区无论在深度上还是在水平位置上基本不重叠.又通过相对定位的方法,发现7月21日主震位于10月16日主震的北西西方向.此外,还通过P波初动极性分析...     

Rupture behavior and deformation localization of the Kunlunshan earthquake (M_w7.8) and their tectonic implications

Earthquake surface rupture is the result of transformation from crustal elastic strain accumulation to permanent tectonic deformation. The surface rupture zone produced by the 2001 Kunlunshan earth- quake (Mw7.8) on the Kusaihu segment of the Kunlun fault extends over 426 km. It consists of three relatively independent surface rupture sections: the western strike-slip section, the middle transten- sional section and the eastern strike-slip section. Hence this implies that the Kunlunshan earthquake is composed of three earthquake rupturing events, i.e. the Mw=6.8, Mw=6.2 and Mw≤7.8 events, respec- tively. The Mw≤7.8 earthquake, along the eastern section, is the main shock of the Kunlunshan earth- quake, further decomposed into four rupturing subevents. Field measurements indicate that the width of a single surface break on different sections ranges from several meters to 15 m, with a maximum value of less than 30 m. The width of the surface rupture zone that consists of en echelon breaks de- pends on its geometric structures, especially the stepover width of the secondary surface rupture zones in en echelon, displaying a basic feature of deformation localization. Consistency between the Quaternary geologic slip rate, the GPS-monitored strain rate and the localization of the surface rup- tures of the 2001 Kunlunshan earthquake may indicate that the tectonic deformation between the Ba- yan Har block and Qilian-Qaidam block in the northern Tibetan Plateau is characterized by strike-slip faulting along the limited width of the Kunlun fault, while the blocks themselves on both sides of the Kunlun fault are characterized by block motion. The localization of earthquake surface rupture zone is of great significance to determine the width of the fault-surface-rupture hazard zone, along which direct destruction will be caused by co-seismic surface rupturing along a strike-slip fault, that should be considered before the major engineering project, residental buildings and life line construction.     

Numerical analysis of contemporary hori-zontal tectonic deformation fields in China from GPS data

Introduction To correctly understand the tectonic deformation of continental lithosphere, its dynamical mechanics and seismic activity, we should firstly acquire the velocity field and strain field of lithospheric tectonic motion with fine resolution and consistent accuracy (Molnar and Lyon-Caen, 1989; Molnar, 1990). And the quality, distribution and density of observed data are the basis for studying crustal tectonic deformation. In the past, crustal deformation is usually determined indi-r…     

2010年青海玉树MS7.1级地震地表破裂带和形变特征分析

通过对SPOT卫星影像上地表破裂的目视解译,以及对ALOS PALSAR卫星数据进行D-InSAR形变提取和分析,结合地震活动性、震源机制、活动构造等资料,确定了发震断层空间分布、断层性质和同震形变场分布特征.结果显示,玉树地震发生在甘孜—玉树断裂带上,总体走向约为300°,断层近乎直立.根据相干性强弱将Ⅰ区地表破裂划分为三段:北段长22 km,中段长5 km,南段长6 km,破裂带总长度约33 km.Ⅱ区内非相干带长约10 km.同震形变场分布在78 km×55 km范围内,主震所在的形变Ⅰ区断层两侧视线向相对位错约为0.78 m,转换成水平位错约为1.5 m;余震所在的Ⅱ区形变相对较小.     

2010年青海玉树MS7.1级地震地表破裂带和形变特征分析

通过对SPOT卫星影像上地表破裂的目视解译,以及对ALOS PALSAR卫星数据进行D-InSAR形变提取和分析,结合地震活动性、震源机制、活动构造等资料,确定了发震断层空间分布、断层性质和同震形变场分布特征.结果显示,玉树地震发生在甘孜—玉树断裂带上,总体走向约为300°,断层近乎直立.根据相干性强弱将Ⅰ区地表破裂划分为三段:北段长22 km,中段长5 km,南段长6 km,破裂带总长度约33 km.Ⅱ区内非相干带长约10 km.同震形变场分布在78 km×55 km范围内,主震所在的形变Ⅰ区断层两侧视线向相对位错约为0.78 m,转换成水平位错约为1.5 m;余震所在的Ⅱ区形变相对较小.     

Active tectonic blocks and strong earthquakes in the continent of China

The primary pattern of the late Cenozoic to the present tectonic deformation of China is characterized by relative movements and interactions of tectonic blocks. Active tectonic blocks are geological units that have been separated from each other by active tectonic zones. Boundaries between blocks are the highest gradient of differential movement. Most of tectonic activity occurs on boundaries of the blocks. Earthquakes are results of abrupt releases of accumulated strain energy that reaches the threshold of strength of the earth's crust. Boundaries of tectonic blocks are the locations of most discontinuous deformation and highest gradient of stress accumulation, thus are the most likely places for strain energy accumulation and releases, and in turn, devastating earthquakes. Almost all earthquakes of magnitude greater than 8 and 80%-90% of earthquakes of magnitude over 7 occur along boundaries of active tectonic blocks. This fact indicates that differential movements and interactions of active tectonic blocks are the primary mechanism for the occurrences of devastating earthquakes.     

Late Quaternary surface deformation and rupture behavior of strong earthquake on the segment north of Mianning of the Anninghe fault

The Anninghe fault is an important active fault along the eastern boundary of Sichuan-Yunnan active tectonic block, and the study of its surface deformation and rupture behavior during strong earthquake in the late Quaternary is of fundamental importance for understanding the future seismic risk of the fault zone or even the entire western Sichuan region. Using the methods of detailed geomorphic and geological survey, digital image analysis, total station instrument survey, excavation of combined trench and dating, we analyze the geomorphologic sequences of the offset strata at several sites where the late Quaternary deformation remnants are fairly well preserved and obtain some new results as follows: Strong earthquake events with left-lateral displacements of about 3 m occurred at the two sites of Zimakua and Yejitong at 1634-1811, 1030-1050 and 280-550 a BP, respectively, and the recurrence interval is 520-660 a; The youngest event in the area of Dahaizi-Ganhaizi should be the earthquake of 1536, other events are at 1768-1826, 2755-4108 and 4108-6593 a BP, respectively, with a recurrence interval of 1300-1900 a. The strong earthquake activity shows a clustering character. The possibility of occurrence of a strong earthquake exists on the north segment of the Anninghe fault sometime in the future.     

鲜水河断裂带炉霍段的震后滑动与形变

1973年2月在鲜水河断裂带炉霍段发生了M7.6地震破裂.自那以来,先后在炉霍县虾拉沱布设了若干横跨该地震断层(1973年破裂带)的地壳形变观测系统,包括断层近场的短基线、短水准、蠕变仪、人工构筑物等,以及断层近-远场的GPS观测站.利用这些观测系统的长期观测资料,本文分析了鲜水河断裂带炉霍段的震后滑动/变形及其时、空变化特征,并建立起解释这些特征的动力学模式.研究表明:(1)1973年地震后的头5年,地震断层在虾拉沱场地表现为开放性质,近场的断层震后滑动以无震左旋蠕滑为主,速率达到10.27 mm/a,且伴有微量的拉张性蠕动作用;1979年以来,左旋蠕滑速率由5.3 mm/a逐渐减小到2.27 mm/a,减小的过程呈对数函数型,反映此阶段断层面已逐渐重新耦合、正朝闭锁的方向发展,并伴有部分应变积累.(2)1999年以来,地震断层两侧远场的相对左旋位移/变形速率为10 mm/a,远大于同时期断层近场(跨距40~144 m)的左旋蠕滑速率0.66~2.52 mm/a;远-近场位移/形变速率的显著变化发生在地震断层两侧各宽约30 km的范围,显示出这是与大地震应力应变积累—释放相关的断裂带宽度.(3)结合动力学背景与深部构造信息,本文对这里断层的震后位移/变形及其时、空变化的机理进行初步解释,要点是:震后约5年之后,由于逐渐增大的断层滑动/摩擦阻抗,上地壳脆性层中的断层面由震后初期的开放性质逐渐转向重新耦合、并朝闭锁的方向发展,但其两侧地块深部持续的延性相对运动拖拽着浅部脆性层发生相应的弹性位移/变形.(4)可估计再经历15~25年,研究断裂段将完全"闭锁",即进入积累下一次大地震应力应变的震间闭锁阶段.     

Earthquake recurrence on whole active fault zones and its relation to that on individual fault-segments

IntroductionEarthquake recurrence models established on activity behaviors of strong earthquakes are the bases of long-term earthquake prediction, seismic risk zonation, and seismic hazard assessment. A lot of studies have been carried out on earthquake recurrence behaviors for specific seismogenic sources or fault-segments, and a series of empirical recurrence models have been proposed, such as the time-predictable model and the slip-predictable model for earthquakes repeated at the previous …     

The neotectonic deformation and earthquake activity in Zhuanglang river active fault zone of Lanzhou

Introduction Zhuanglang river active fault zone, which located in the western of Zhuanglang river valley, north of Hekou, the Xigu district of Lanzhou city, is composed of several echelon small faults, these faults display not very clear on surface. Predecessors thought that this fault from Yongdeng to Hekou was active in Late Pleistocene and even in Holocene through limited research works, they also believed that these earthquakes with magnitude 641 happened at Yongdeng and magnitude 521 …     

Rupture behavior and deformation localization of the Kunlunshan earthquake (<Emphasis Type="Italic">M</Emphasis><Subscript><Emphasis Type="Italic">w</Emphasis></Subscript>7.8) and their tectonic implications

Earthquake surface rupture is the result of transformation from crustal elastic strain accumulation to permanent tectonic deformation. The surface rupture zone produced by the 2001 Kunlunshan earthquake (M _w 7.8) on the Kusaihu segment of the Kunlun fault extends over 426 km. It consists of three relatively independent surface rupture sections: the western strike-slip section, the middle transtensional section and the eastern strike-slip section. Hence this implies that the Kunlunshan earthquake is composed of three earthquake rupturing events, i.e. the M _w =6.8, M _w =6.2 and M _w ⩽=7.8 events, respectively. The M _w =7.8 earthquake, along the eastern section, is the main shock of the Kunlunshan earthquake, further decomposed into four rupturing subevents. Field measurements indicate that the width of a single surface break on different sections ranges from several meters to 15 m, with a maximum value of less than 30 m. The width of the surface rupture zone that consists of en echelon breaks depends on its geometric structures, especially the stepover width of the secondary surface rupture zones in en echelon, displaying a basic feature of deformation localization. Consistency between the Quaternary geologic slip rate, the GPS-monitored strain rate and the localization of the surface ruptures of the 2001 Kunlunshan earthquake may indicate that the tectonic deformation between the Bayan Har block and Qilian-Qaidam block in the northern Tibetan Plateau is characterized by strike-slip faulting along the limited width of the Kunlun fault, while the blocks themselves on both sides of the Kunlun fault are characterized by block motion. The localization of earthquake surface rupture zone is of great significance to determine the width of the fault-surface-rupture hazard zone, along which direct destruction will be caused by co-seismic surface rupturing along a strike-slip fault, that should be considered before the major engineering project, residental buildings and life line construction. Supported by the National Natural Science Foundation of China (Grant No. 40474037) and the National Basic Research Program of China (Grant No. 2004CB418401)     

北京地区区域性形变场与近期强震危险性研究

分析1998－2000年期间水准和GPS测量给出的北京地区区域性形变场的背景值及其与定点断层形变观测值的关系。结果表明：（1）该地区的大面积垂直形变速率及速率梯度值在华北地区的通常 数值之下，也低于若干大地震前的相应异常特征值；（2）该区由GPS方法显示的大面积水平形变速率也属于较低水平；（3）定点观测的断层形变速率（垂直向和水平向）与区域性的背景值相当；（4）根据大面积形变场的 断层形变异常水平，预计近期（1－3年内）北京地区不会发生较强地震。     

中国西部及邻区活动地块边界带现代构造应力场

利用哈佛全球矩心矩张量解数据和许忠淮认为1920mdash;1999年可靠的中国大陆震源机制解数据, 反演了中国西部及邻区活动地块边界带上现代构造应力场．通过对FMSI反演程序多次的输入和检验, 得到了边界带上的应力场．边界带上最大主压应力sigma;1轴绝大多数近水平. 在90deg;E以西的中国西部大陆及邻区, sigma;1轴水平方向基本上为近SN向;在青藏高原的东北部, sigma;1轴水平方向基本上为近NE向;在青藏高原的东南部, sigma;1轴水平方向绕喜马拉雅构造东端顺时针方向旋转．最小主压应力sigma;3轴倾角呈两极分布,西域地块区内活动地块边界带和青藏地块区内东北缘部分段sigma;3轴倾角较陡, 而青藏地块区内sigma;3轴倾角近水平, 所以西域地块区和青藏地块区内东北部相对于其它大部分青藏地块区, 有更多的逆冲地震．应力场在同一个边界带具有非均匀性. 北天山带、南天山带、西秦岭mdash;德令哈带、岷山mdash;龙门山带和安宁河mdash;小江带的非均匀性相对要小一些, 西昆仑带、海原mdash;祁连带、东昆仑带、玛尼mdash;玉树带、澜沧江带和滇西西边界带的非均匀性相对要大, 而喀喇昆仑mdash;嘉黎带和喜马拉雅带的非均匀性最显著．由于震源机制解数据的限制, 本文给出的是边界带上部分段的应力场．      

1997年伽师强震群活动的近场定点形变异常特征

对１９９７年伽师强震群前后的近场宁点形变资料和卡尔曼滤波结果的前兆异常进行了分析,结果表明,震前短临异常较为明显。通过密切跟踪,在后续强震的预报中发挥了重要作用。文中还对异常与孕震构造和应力场的关系进行了讨论。     

基于构造的测震学参数在鲁东-黄海地块的应用

以基于构造的测震学参数分析为思路,利用地震构造分区和地质构造单元的划分结果,检验了基于活动边界带的测震学参数方法的可行性;将活动地块内部（地质构造复杂且地震活动频繁）构造单元与测震学参数相结合,研究中强震前震源区所在的构造单元测震学参数的变化特征,提取具有中期预测意义的震兆标志,为中强震的预测提供理论依据。结果显示：中强地震前,郯庐断裂带（鲁东-黄海地块西边界带）及扬子地块（鲁东－黄海地块内部构造单元）D、C值异常过程明显,且各有特点,证明了基于活动地块内部构造单元的测震学参数方法具有良好的可行性。     

基于GPS应变与震源机制解应力反演喜马拉雅构造带现今地壳形变特征

喜马拉雅构造带及其临近区域是印度板块与欧亚大陆板块挤压碰撞的前缘地带.本文利用GPS实测速度场与震源机制解数据分别计算了研究区域现今地壳岩石圈表面的GPS应变场及岩石圈内部的主应力分布,研究了印度板块持续挤压作用下板块边界带地壳岩石圈现今地壳形变的空间分布特征.结果显示,南北向的剧烈挤压变形与东西向的拉伸变形是现今青藏高原南缘地壳岩石圈的主要变形特征.其中南北向的地壳挤压变形主要集中在主前缘冲断带与雅鲁藏布江缝合带之间.东西方向上,南北走向的亚东—谷露断裂是区域地壳东西向伸展变形的重要分界断裂.75°E是研究区域地壳形变的另一条显著不连续边界,其西侧地壳主压应变强度低、方向弥散且最大主压应力方向一致性较差,而东侧地壳主压应变方向与主压应力方向以及地壳水平运动速度场方向均具有较好的一致性.布格重力异常的小波多尺度辨析结果显示该分界带与循喜马拉雅西构造结楔入欧亚大陆的印度板块密切相关.     

2005年11月26日江西九江-瑞昌Ms5．7地震序列的破裂过程研究

利用江西南昌遥测台网和临时台网资料,借助于主地震相对定位法,对2005年11月26日江西九江-瑞昌MS5.7地震序列进行了重新定位,分析了该序列的破裂过程。这次地震的余震震中呈线性分布,约沿北西37°,与美国哈佛大学给出的主震震源机制解中的N35°W节面和北西向的洋鸡山-武山-通江岭断裂的走向基本一致,震中位于该断裂的东南端。这次地震破裂扩展过程主要发生在2005年11月30日19时前,其后平稳。主震发生在余震分布区的西北端部,似乎表明本次地震为单侧破裂,破裂向东南方向扩展。震后4小时内震源深度由浅到深变化,之后逐渐稳定在15 km左右。破裂过程大致可分为两个阶段:第1个阶段是从主震到2005年11月26日16时22分0.8秒,破裂尺度为13.8 km,历时约7.54小时,平均破裂速度约为50.8 cm/s;第2个阶段是从2005年11月29日11时35分21.7秒到2005年11月30日19时57分58秒,破裂尺度为17.9 km,历时约32.4小时,平均破裂速度约为15.4 cm/s。整个破裂过程扩展了31.7 km,平均破裂速度约为22 cm/s,前一阶段速度明显高于后一阶段,破裂是减速的。     

Surface rupture zone of the 1303 Hongtong M=8 earthquake, Shanxi Province

Introduction The 1303 Shanxi Hongtong M=8 earthquake is the earliest M=8 event determined in histori-cal records in China and the largest recorded in Shanxi fault-depression system in history. Some researchers have discussed the tectonic environment of this earthquake (DENG, et al, 1973; DENG, 1984; DENG, XU, 1994, 1995; Seismo-geological Brigade, State Seismological Bureau, Depart-ment of Geology and Geography, Peking University, 1979; LIU, XIAO, 1982; ZHANG, JIA, 1986; SU, …     

川滇交界东段昭通、莲峰断裂带的地震危险背景

川滇交界东段NE向昭通、莲峰断裂带的研究程度较低.为了了解该断裂带是否存在发生强震/大地震的危险背景,我们基于区域活动构造与动力学、重新定位的小震分布和震源机制解、历史地震破裂区、GPS形变场、现代地震活动及其参数图像等多学科的信息进行综合研究.结果表明:昭通、莲峰断裂带是川滇-华南活动块体/地块边界带的一部分,也是活动及变形的大凉山次级块体与相对稳定的华南地块之间的边界带;结构上表现为2个平行展布、朝南东推覆的断裂带,现今运动为带有显著逆冲分量的右旋走滑性质.沿昭通断裂带无大地震的时间至少为1700 余年,目前存在地震空区.GPS变形图像反映昭通、莲峰断裂带已不同程度闭锁.另外,昭通断裂带的鲁甸附近以及莲峰断裂带的南段分别存在异常低b值区或高应力区.已由低b值区和小震空白区识别出昭通断裂带上的鲁甸—彝良之间存在高应力闭锁段,并估计出其潜在地震的最大矩震级为MW7.4.本研究因此认为昭通断裂带存在发生强震/大地震的中-长期危险背景, 而莲峰断裂带的危险性还需进一步研究.