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Identification and Correction for MT Static Shift Using TEM Inversion Technique

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Journal of china University of Geosciences 2001年第3期12卷 266-271页

作者： Yang ChangfuDepartment of Earth Science, Nanjing University, Nanjing 2.0093Lin ChangyouLanzhou {1. of Seismology, china seismological bureau, Lanzhou 730000 Department of Earth Science Nanjing University Nanjing 210093 Lanzhou institute of Seismology China Seismological Bureau Lanzhou 730000

The inversion of TEM data, using the observed magnetic fields instead of that of apparent resistivities data in this paper, avoids the errors caused by the definition of the apparent resistivity. The inversed results by fitting the magnetic fields of the transmitter source's image with the observed magnetic fields are relatively less affected by the conductivity inhomogeneity. The MT apparent curve is calculated on the basis of the conductivity model constructed from the TEM inversion results. This curve is used as a reference curve for the correction of MT static shift, which makes the correction more reliable. Meanwhile, the domain transformation is also achieved from time to frequency between the two kinds of electromagnetic data. Therefore, the correction of the MT static shift is actualized using TEM inversion method. The corresponding application research shows that this method is very effective for the identification and correction of the MT static shift.

关键词： TEM inversion MT correction of static shift.

High-Resolution Seismic Reflection Profiling of the Fenhe Fault in Taiyuan City

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Earthquake Research in china 2003年第1期17卷 73-84页

作者： You Huichuan, He Zhengqin, Ding Zhifeng, Wu Jianping and Wu Qingjuinstitute of {1.,{2., Beijing 1.0081. china institute of {1. China Seismological Bureau Beijing 100081 China

In this paper, we demonstrate the high resolution seismic reflection data for a depth range of several hundred meters across the Fenhe fault in Taiyuan city, china. In combination with the relevant borehole logs, these data provide useful constraints on the accurate position, geometry and deformation rate of the fault, as well as the kinematics of recent fault motion. The high resolution seismic reflection profiling revealed that the western branch of the Fenhe fault is a high angle, eastward dipping, oblique normal fault, and cutting up to the lower part of the Quaternary system. It was revealed that the top breaking point of this fault is at a depth of ～70m below the ground surface. A borehole log across the Fenhe fault permitted us to infer that there are two high angle, oppositely dipping, oblique normal faults. The eastem branch lies beneath the eastern embankment of the Fenhe river, dipping to the west and cutting into the Holocene late Pleistocene strata with a maximum vertical offset of ～8m. Another borehole log across the northern segment of the Fenhe fault indicates that the western branch of this fault has cut into the Holocene late Pleistocene strata with a maximum vertical offset of ～6m. The above mentioned data provide a minimum average Pleistocene Holocene vertical slip rate of 0 06～0 08mm/a and a maximum average large earthquake recurrence interval of 5 0～6 7ka for the Fenhe fault.

关键词： Taiyuan city Fenhe fault High resolution seismic reflection profiling

A Study of the Crustal Stability in the Yangtze Three Gorges Area

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工程科学（英文版） 2003年第1期1卷 23-31,56页

作者： Li Ping 1. Li Yuanjun 2.(1.{1. of Geology, china seismological bureau, Beijing 1.002.) (2.College of Civil Construction Engineering, Wuhan University, Wuhan 430072.

The Three Gorges Dam on the Yangtze River is situated on the intact rock mass composed of diorite granite at the southern termination of the Huangling block which, as a sub plate with a double layer structure (crystalline basement and sedimentary cover) in the Chinese inland, keeps a constant but slow uplift as a whole since its formation in the Indoncisia movement. Tectonic deformation within the block is not significant, with the exception of a slight southeastward tilt. The block is confined by many active structures, of which the sub longitudinal Yuanan and Xiannvshan ( Mount Fairy ) deep fault zones are the main strongly seismogenic zones. The Yuan’an fault zone represents a regional boundary among West Henan, West Hubei and West Hunan mountainous regions as well as the Nanyang, Jianghan and Dongting Lake basins, with a total length of more than 1.000 km. Two M 6 5 earthquakes (in Changde and Nanyang) occurred in the fault zone in historic time and the distance between the two epicenters is about 500 km. The Mount Fairy fault zone extends northward along the Xiangxi River and ends at the Qingfeng fault. It runs a total length of more than 2.0 km. southward across Yuyang Pass and then its trace is unknown. The fault zone has a tectonic condition for occurrences of M 6.0 earthquakes. The possible seismic risk for the dam may come from these two strong seismogenic zones. Thus the seismic intensity to influence the dam is estimated to be Ⅵ～Ⅶ and the horizontal peak acceleration to be 0 1.0 1. g.

关键词： Three Gorges Dam on the Yangtze Huangling block strong seismogenic zone crustal stability

DIVISION AND MOTION OF LATE QUATERNARY ACTIVE BLOCKS AROUND THE NORTHEASTERN MARGIN OF THE TIBET PLATEAU

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Scientia Geologica Sinica 2001年第2期 101-116页

作者： Guo Shunmin institute of Geology,{1., Beijing 1.002. Jiang Zaisen Second Crustal Deformation Monitoring Center,{1., Xi’an 71.054 Zhang Chongli institute of Geology,{1., Beijing 1.002

This study aims to serve earthquake prediction. Six division principles are introduced. Practical materials as division bases are briefly described. The study area is divided into 7 first-order blocks and 33 second-order blocks. Most of these blocks show obvious compression, squeezing and rotation. Especially the motions of blocks related to the Aljin fault, the Qilian Mts east marginal fault and the Xiang Mts-Tianjing Mts-Liupan Mts east marginal fault are discussed in detail. Crustal thickness, gravity and magnetic anomalies as well as the distribution of active faults and strong earthquake epicenters provide strong supports for block division.

关键词： DIVISION AND MOTION OF LATE QUATERNARY ACTIVE BLOCKS AROUND THE NORTHEASTERN MARGIN OF THE TIBET PLATEAU Lake NEE than III

Burst strain disturbance—A new test study on fracture precursor

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Acta Seismologica Sinica(English Edition) 1998年第6期11卷 81-88页

作者： ZHAO YONG XU 1. RUN HAI YANG 1. BIN WANG 1. JIN MING ZHAO 1. YU FENG YAO 1. PEI ZHONG HUA 1. SHI RONG MEI 2. 1. {1. bureau of Yunnan Province, Kunming, 650041.{2. 2. Center for Analysi 1. seismological {1. of Yunnan Province 650041 Kunming China 2. Center for Analysis and Prediction China Seismological Bureau 100036 Beijing China

A multi functional high frequency seismometer, a new instrumental system, is used for recording multi point strain variations of rock samples in the process of fracture development. The results indicate that strain in each point appears burst disturbance synchronously besides a tendency variation before main fracture. The burst disturbance could probably be one of the short impending precursors before great earthquake.

关键词： burst disturbance short impending precursor fracture precursor

QUATERNARY GROWTH FOLDS IN THE JIUXI BASIN AT THE NORTHEASTERN MARGIN OF THE QINGHAI—XIZANG PLATEAU

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地学前缘 2000年第S1期7卷 333-334页

作者： Chen Jie 1. Karl\|Heinz Wyrwoll 2. Annette George 3,Lu Yanchou 1.(1.{1. of Geology, china seismological bureau, P.O.Box 9803,Beijing 1.002.,{2., E\|mail:chenjie@*** 2.Department of Geography, University of Western Australia, N

As a consequence of the collision of India with Asia, the Qilian Shan, rising 4000～5000m above the Gobi, marks the northeastern boundary of the Tibet—Qinghai Plateau. The Qilian Shan developed as a WNW—ESE fold\|and\|thrust belt with most of the movement directed towards the NEN—NE. Its foreland margin, the Jiuxi Basin, accommodates thick sequences of Late Cenozoic alluvial sediments derived from the Qilian Shan. Thin\|skinned fold\|and\|thrust deformation in the Jiuxi basin flanking the Qilian Shan, feature Mesozoic and Cenozoic sedimentary rocks that have been detached from the underlying basal decollement and folded into a series of NW—WNW trending anticlines and synclines. Towards the south deformation in the Jiuxi basin is accommodated by a west\|north\|west fold train (Qingcaowan, Laojunmiao, and Shiyougou folds) developed during the Quaternary. These form a distinct topographic feature separating the Qilian Shan from the central Jiuxi Basin. The doubly plunging Laojunmiao anticline is 1.km long and 5km wide. It is asymmetric in shape, having a steep to overturned northern limb, and a backlimb dips to the south at 2.～30°. The Laojunmiao anticline is composed of two distinct stratigraphic sequences which are defined by a syntectonic unconformity.

关键词： Qilian Shan Quaternary growth fold growth strata erosion rate uplift rate

ThesourceparametersandsourcemechanismfortheJanuary5,1.98JingyangearthquakewithMS=4.8

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Acta Seismologica Sinica(English Edition) 1998年第6期11卷 114-116页

作者： WEI DONG WANG PING WANG seismological {1. of Shaanxi Province, Xi′an 71.068,{2. 1. seismological {1. of Shaanxi Province 710068 Xi’an China

ＡｎｅａｒｔｈｑｕａｋｅｗｉｔｈＭＳ＝４．８ｏｃｕｒｅｄｎｅａｒＹｏｎｇｌｅＴｏｗｎｉｎＪｉｎｇｙａｎｇＣｏｕｎｔｙ，ＳｈａａｎｘｉＰｒｏｖｉｎｃｅｏｎＪａｎｕａｒｙ５，１９９８．Ｉｔｓｅｐｉｃｅｎｔｅｒｉｓ３４．５... 详细信息

ＡｎｅａｒｔｈｑｕａｋｅｗｉｔｈＭＳ＝４．８ｏｃｕｒｅｄｎｅａｒＹｏｎｇｌｅＴｏｗｎｉｎＪｉｎｇｙａｎｇＣｏｕｎｔｙ，ＳｈａａｎｘｉＰｒｏｖｉｎｃｅｏｎＪａｎｕａｒｙ５，１９９８．Ｉｔｓｅｐｉｃｅｎｔｅｒｉｓ３４．５°Ｎ，１０８．９°Ｅ，ｏｒｉｇｉｎ...

关键词： Jingyang earthquake digital seismic network source parameters source mechanism

Thermal Structure and Rheology of the Upper Mantle beneath Guangdong and Hainan Provinces,china

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Continental Dynamics 1999年第1期 23-32页

作者： LIN Chuanyong and SHI Lanbin institute of Geology, {1. {2. of china, Beijing 1.002., china HAN Xiuling institute of Geology, Chinese Academy of Sciences, Beijing 1.002., china CHEN Xiaode institute of Geology, {1. {2.

The geotherm and rheology of the upper mantle beneath Guangdong and Hainan Provinces are derived from the detailed study of spinel lherzolite and garnet websterite xenoliths from these areas. The constructed upper mantle geotherm is higher than the oceanic geotherm, but is slightly lower than those for the upper mantle beneath eastern china constructed by Xu et al. (1.95) and for southeastern Australia constructed by O’Reilly et al. (1.85). The high geotherm is considered to be related to the upper mantle diapir that occurred in this area. The crust mantle boundary defined by this geotherm is about 33 km deep, indicating the underplating of upper mantle materials. The rheologic features of the xenoliths show that the upper mantle beneath these areas was subjected to a relatively strong deformation process, which might be related to upper mantle diapir. During this process the differential stress might reach up to 50 MPa. As a result, high strain rate, low viscosity zones occurred at the depth of 65 km. These zones are believed to be upper mantle shear zone. The lithosphere asthenosphere boundary was deduced to be at the depth of about 85 km. All these results coincide well with the available geophysical data.

关键词： mantle xenolith upper mantle geotherm rheology Guangdong Province Hainan Province

GENETIC ANALYSIS OF ANOMALOUS VARIATION OF WATER TABLE IN CHANGPING WELL, BEIJING

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地震地质 1991年第4期 312-316+311页

作者： Yang Hui-nian(institute of Geology, State {1. {2., Beijing 1.002.)

Field investigation on hydrogeological environment around Changping well reveals that the anomalous uprise of ’water table begining from Oct. 1.88 was mainly caused by the leakage of water from the channel leading to... 详细信息

关键词： Changping well Anomalous water table Shisanling Reservoir Paleochannel Water diversion Pecolation recharge