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Discussion on origin of Pn velocity variation in China and adjacent region

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Acta Seismologica Sinica(English Edition) 2004年第1期17卷 1-11页

作者： PEI Shun-ping(裴顺平) XU Zhong-huai(许忠淮) WANG Su-yun(汪素云) Computational Geodynamics Laboratory Department of Geophysics Peking University Beijing 100871 China Institute of Geophysics China Seismological Bureau Beijing 100081 China Institute of Geophysics China Seismological Bureau Beijing 100081 China

Pn velocity lateral variation and anisotropy images were reconstructed by adding about 50 000 travel times from the regional seismic networks to the datum set of near 40 000 travel times from National Seismic Network of China used by WANG, et al. We discussed the relation of Pn velocity variation to Moho depth, Earths heat flow, distribution of Cenozoic volcanic rock and the result of rock experiment under high pressure and high temperature. The result of quantitative analysis indicates that Pn velocity is positively correlated with the crust thickness and negatively correlated with the Earths heat flow. Two linear regression equations, one between Pn velocity and crust thickness, and the other between Pn velocity and heat flow, were obtained. The rate of variation of Pn veloc-ity vP with pressure P, Pv/p, estimated from the velocity variation with crust thickness Hv/p, is close to the result obtained from the rock experiment under high pressure and high temperature. If the effect of crust thick-ness on Pn velocity is deducted from the velocity variation, then the low Pn velocity beneath Qinghai-Xizang pla-teau is more notable. The low Pn velocity regions well agree with the Cenozoic volcanic rock. In the several re-gions with significant anisotropy, the direction of fast Pn velocity is consistent with the orientation of maximum principal crustal compressive stress, and also with the direction of present-day crustal movement. It indicates that the fast Pn velocity direction may be related to the deformation or flow of top mantle material along the direction of maximum pressure.

关键词： Pn tomography anisotropy China and adjacent region

The method of design for seismic data database system based on tree structure

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Acta Seismologica Sinica(English Edition) 2005年第1期18卷 99-105页

作者：王喜珍滕云田高孟潭陈步云姜慧 institute of geophysics China Earthquake Administration institute of Seismology China Earthquake Administration

With the massive growth of the seismic data, it is required a new method to manage them. In this paper, the design method will be reported about relational database based on tree structure. Comparing with other designs, it is not only simpler and easier to organize data, but also can simplify the design process of the database. This method has been used to design database of the earthquake monitor center station of the earthquake monitoring system for the Yangtze River Three Gorges Project and has shown good results.

关键词： tree structure relational database conversion

Rupture process of November 6,1988,Lan-cang-Gengma,Yunnan,China,earthquake of M_s=7.6 using empirical Green’s function de-convolution method

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Acta Seismologica Sinica(English Edition) 1998年第1期11卷 1-12页

作者：吴忠良陈运泰 1. institute of geophysics State Seismological Bureau 100081 Beijing China 2. institute of geophysics Tehran University 14394 Tehran Iran

The empirical Green's function deconvolution technique is applied to the November 6, 1988, Ms=7.6, Yunnan, China earthquake to study the rupture process of this event. An aftershock of Ms=6.3 is taken as the empirical Green's function. Recordings of these two events at six stations of China Digital Seismographic Network (CDSN) are employed. Deconvolution results show that this event is a relatively simple event. Directivity analysis indicates that the rupture was initiated at hypocenter and propagated bilaterally and nearly symmetrically towards the northwest and southeast directions with a total length of 70 km and a time duration of 19 s. The rupture velocity is estimated to be about 2.0 km/s.

关键词： Lancang Gengma earthquake empirical Green's function source time function rupture directivity

Rock magnetic studies on the hominoid-bearing sediments at Zhupeng, Yuanmou Basin, southwestern China and its paleoclimatic significance

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Chinese Science Bulletin 2005年第15期50卷 1653-1660页

作者： YAO Haitao LIU Qingsong Lü Lianqing CHANG Zhigang ZHU Rixiang Paleomagnetism Laboratory Institute of Geology and GeophysicsChinese Academy of Sciences Beijing 100029 China institute of geophysics and Planetary geophysics University of California Santa Cruz CA 95064 USA

It has been proposed that paleoclimatic changes and tectonic events strongly affect hominoid evolution. The Zhupeng section at Yuanmou Basin, southwestern China, with the hominoid-bearing fluvial-lacustrine sediments, is an ideal natural laboratory to test this hypothesis. This study provided an integrated magnetic study, including low-fre- quency susceptibility, the anisotropy of magnetic susceptibil-ity, temperature-dependent susceptibility, hysteresis loops, isothermal remanent magnetization, and anhysteretic rema-nent magnetization, on samples from the Baozidongqing section at Zhupeng. Results show that the dominant mag-netic carrier is hematite, with minor amount of magnetite. Both the composition and concentration of magnetic miner-als strongly correlate with the lithostratigraphy. At least eight short-term events defined by higher concentrations of magnetite were identified. These short events reflect that the subtropical dry-hot climate is similar to today’s climate. Basing on the lithostratigraphic and rock magnetic results, we suggest that Yuanmou Basin was in a steady deposition environment from about 11 to 7 Ma, which is characterized by alternating of long-term torrid-humid climate and short-term dry-hot climate. Our study provides invaluable environment information for understanding the climate shift and the relationship between paleoenvironment and homi-noid evolution in southwestern China during late Miocene.

关键词：中国古气候类人猿元谋人

Study on the earthquake fault of the Lulong ML=6.2 earthquake by precise relocation of aftershock

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Acta Seismologica Sinica(English Edition) 2005年第4期18卷 402-409,499页

作者：李文军王培德李春来陈棋福 institute of geophysics China Earthquake Administration institute of geophysics China Earthquake Administration Beijing 100081China institute of Earthquake Science China Earthquake Administration Beijing 100036 China

We have selected 171 near-field records from 391 aftershock records of the Lulong, Hebei Province, earthquake in October 1982 and relocated the hypocenter of 45 aftershocks using the program Hypoinverse. The distribution of aftershocks reveals a set of earthquake faults: a WNW stretching fault truncates two NNE stretching faults. The two branches of faults show the conjugate structure which is often seen in brittle fracture. The NNE stretching faults are connected together. The Luanhe river valley near Lulong developed to a rudiment rift basin surrounded by a series of faults. The fault of Lulong earthquake is a strike-slip fault with tension component. This fault type matches with the activity of Zhangjiakou-Bohai seismic belt (Zhang-Bo belt) and also shows the action of Zhang-Bo belt as a boundary of two secondary active blocks that truncates the NNE fault.

关键词： ML=6.2 earthquake Zhangjiakou-Bohai seismic belt Hypoinverse location method seismogenic structure

3D S-Wave Velocity Structure of the Crust and Upper Mantle

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Science China Chemistry 1994年第1期37卷 104-116页

作者：宋仲和安昌强陈国英陈立华庄真傅竹武吕梓龄胡家富 institute of geophysics State Seismological Bureau Beijing 100081 PRC Department of geophysics Yunnan University Kunming 650091 PRC

In this paper, 238 Rayleigh wave path data are selected and processed by the matched-filtering frequency-time analysis technique and the grid dispersion inversion method to obtain the 3D S-wave velocity structure of China mainland and its adjacent sea regions. The results show that the velocity structure relates to geotectonic division, Bouguer gravity anomaly is basically controlled by the relief of Moho discontinuity, the buried depth of LVL in upper mantle concerns the surface heat flow deeply. In this paper, authors indicate the main characteristics of the velocity structure in tectonic active and stable regions.

关键词： dispersion curve of Rayleigh wave group velocity matched-filtering frequency-time analysis technique grid dispersion inversion 3D S-wave velocity structure geotectonic division.

Seismic tomography of the crust and upper mantle in the Bohai Bay Basin and its adjacent regions

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Science China Earth Sciences 2007年第12期50卷 1810-1822页

作者： ZHANG Ling LIU JinSong HAO TianYao LIU JianHua XU Yi institute of Geology and geophysics Chinese Academy of Sciences Beijing 100029 China Gocad Research Group Rue Doyen M. Roubault 54501 Nancy France Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

In the Bohai Bay Basin and its adjacent regions(112°―124°E,34°―42°N),there exists abundant gas-petroleum while modern inter-plate seismic activity is *** the tectonic structure of this region is very complicated,plenty of geological,geophysical and geochemical data and results are obtained through previous *** the basis of absorbing previous results,especially various kinds of geological and geophysical results,we collect and process the arrival time of P-wave phases of local events and tele-seismic events recorded by the station within this region from 1978 to 2004,build the responding initial model,and image the velocity structure of the crust and upper mantle of this region via *** perturbation images of various depths and velocity profiles imply that the velocity structure of the crust and upper mantle in the Bohai Bay Basin and its adjacent regions is mainly influenced by the surface tectonic units,and is characterized by "Stripped along east-west,and zoned along south-north";some large-scaled faults penetrate Moho and lithosphere,and provide the channels for the basic lava or hot mass upwelling from the mantle.

关键词： Bohai Bay Basin, tomography, crust and upper mantle

Multiplet relative location approach and waveform correlation correction and their application

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Acta Seismologica Sinica(English Edition) 2003年第6期16卷 606-615页

作者：白玲张天中张宏智 institute of geophysics China Seismological Bureau Beijing 100081 China

The theory and method of relative location technique were described in the paper. The travel-time difference equa-tions for five phases (Pg, Sg, P11, S11 and Pn) were given. By using the multiplet relative location approach and wave correlation correction, the aftershock cluster of the Shunyi earthquake occurred on December 16, 1996 was relocated. The depth calculation was constrained by using multiple seismic phases. The relocation results were compared with that from traditional absolute location techniques.

关键词： multiplet relative location approach waveform correlation correction P11 S11 Pn Shunyi earthquake

Changes in Air Temperatures and Atmosphere Circulation in High Mountainous Parts of Bulgaria for the Period 1941-2008

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Journal of Mountain Science 2012年第2期9卷 185-200页

作者： Peter NOJAROV National institute of geophysics Geodesy and GeographyBulgarian Academy of Sciences

Changes of air temperatures and atmosphere circulation at three high mountainous stations in Bulgaria are investigated for the period of *** three stations are located on peaks Musala,Cherni vrah and Botev,where air temperature data have good *** missing data were recovered using the method of differences. A significant mean annual air temperature rise happened in high mountainous parts of Bulgaria- the warming is in the order of 0.7°C for the entire *** increase is very prominent particularly in the last 30 *** contributors to this overall tendency are summer months-June,July and *** some degree,January also could be included in this *** trend shows temperature rise at the beginning of the investigated *** of the causes for such a tendency is atmosphere circulation in respective *** also shows signs of considerable reorganization in both winter and *** is an increase of the cases of warm atmosphere patterns typical for winter, summer and autumn seasons in *** circulation has essential significance for air temperatures during the cold half of the *** January and June atmosphere circulation has a substantial influence on the thermal regime of air in high mountains of *** July,August and November this influence is *** are no cycles in air temperatures for the investigated period.

关键词： Air temperature Trends Atmosphere circulation Bulgaria Mountains