ZHANG Dong-li , TA Xia xin , ZHU Zheng-hua
2005, 27(3):193-198.
Abstract:For a point on fault,the slip-time function can be described by three parameters,the average displacement,rising time and time delay of wave propagation. In this paper, based on finite fault model,according to heterogeneons displacement distribution in temporal and spatial of the sub-source,the parameters of slip-time function are determined and the finit fault model with uniform displacements is presented. The method not only described the complexity of earthquake source but also simplified the finite fault model, which provided an effective input for numerical simulation of near-field strong ground motion.
BO Wan-ju , LIU Guang-yu , CHEN Bing , LIU Tian-hai , GUO Liang-qian , DU Xue-song
2005, 27(3):199-204.
Abstract:Based on the data of leveling across faults in northeast margin area of Qinghai--Tibet block,the statistics, comparison, analysis and study are made on three aspects as follows: the spatial distribution of abnormal fault deformation, the average rate of fault movement in different belt, and the distribution of group abnormal fault deformation in time dimension. The results show that, since 2002, the principal region of fault deformation anomolies are transferred gradually from west to east in northeast margin area of Qinghai--Tibet block; the seismic activities are also similarly transferred from west to east; and the average rate of fault movement in the east part is higher than other parts of the research area. But the distribution of group abnormal fault deformation in time dimension shows that, at present, the anomalies are not distinct enough in magnitude and amount, thus, it's impossible having strong earthquake in this area in near future. The primary results and the study method presented in this paper have a reference value for daily work of earthquake prediction and seismic trending research.
Yukitake SHIOI , Yutaka HASHIZUME , Hisasi FUKADA
2005, 27(3):205-211.
Abstract:A new hypothesis clarifies the phenomenon of liquefaction of saturated sandy soil during large earthquakes. It is based on the multi-reflection theory and dynamic response calculation using FEM. The results using the hypothesis applied to soil at Hachinohe Port during the 1994 Far--Off Sanriku Earthquake (M=7.5) in calculating, showed good correspondence with the observed phenomena associated with this earthquake. The method was applied to other areas that had liquefied in the past and confirmed within acceptable limits the mechanism of liquefaction. The Fukui Earthquake (June, 1948,M=7.1) occurred at depth of 15 km at the center of the Fukui basin and caused widespread damage and 5 300 casualties. The earthquake induced largescale liquefaction everywhere and covered rice field over a wide area with sand and gravel. However, regardless of very strong acceleration several parts of the basin did not liquefy. Using the hypothesis, we analyzed differences in surface layer under the same conditions. As a result, we found that the liquefaction depends on the size of strain caused by the rigidity of the surface layer and that the hypothesis accurately corresponds to what happens in practice.
Kazama M , Uzuoka R , Sento N , N Unno T
2005, 27(3):212-219.
Abstract:The possibility of a flow failure due to seepage with the redistribution of the excess pore water pressure after liquefaction has been pointed out. To study this phenomenon, the seepage shear failure of the soils subjected to pore water injection is examined by laboratory tri-axial test. In the test, after anisotropic consolidation, keeping the deviator stress, pore water is injected using pore water control apparatus under a constant volumetric strain controlled condition. The materials used in the tests are ordinary fine clean sand and the weathered granite soil, which liquefied during the 1995 Kobe earthquake. Based on the test results, the seepage shear failure criteria due to pore water injection and the shear strain development characteristics regarding a postliquefaction behavior are discussed.
LIU Guo-hui , CHEN Li , ZHOU Shu-min , JIA Xue-min
2005, 27(3):220-222,227.
Abstract:The problems about the method of shear wave velocity to value the liquefaction of the saturated soil are discussed. Combining with the site condition a improved formula is proposed to calculate the critical shear wave velocity. Case study shows that improved method has move reasonable advantage in use.
GUO Xiao , ZHANG Yuan-sheng , ZHONG Mei-jiao
2005, 27(3):223-227.
Abstract:Through retrieving the data of NOAA--AVHRR, the daily land surface temperature distribution images before and after some earthquakes are obtained by using the land surface temperature calculation model of Becket & Li. Then these images and the curve of daily land surface temperature average value for the epicenter area of the events are analyzed. The result shows that there are visible thermal infrared precursor anomalies before the earthquakes. Finally, it is pointed out that the retrieving land surface temperature from NOAA--AVHRR data by split window technique is fairly disturbed by cloud layers, but as the appearance of EOS/MODIS data with high space and spectrum resolution and their capability of observing land surface temperature through cloud layer, the thermal infrared information of satellite remote sensing will be more deeply and widely appplied in earthquake prediction.
ZHANG Hui , ZHANG Xin-ji , SU He-jun
2005, 27(3):228-232.
Abstract:Based on the study of relationship between micro-fissure generation in rock and radon concentration in groundwater ,as well as the micro-fissure spatial-temporal changing image in the process of earthquake preparation, the spatial-temporal characteristics of radon precursory field and its physical mechanism are exposed. The results show that the augment of radon content in groundwater and radon anomalies before earthquake are caused by micro-fissure generation in rock in the process of earthquake preparation. Radon anomalies first emerges and mainly focus in the source and adjacent region because dilatancy and micro-fissure first emerge and concentrated also in this region. Increased micro-fissure produces increasing content of radon in the groundwater, so the tendency anomaly of radon exhibits mainly a rising tendency.
ZHANG Shu-xun , WEI De-hong , ZHANG Xiao-mei , HAO Zhen
2005, 27(3):233-239.
Abstract:Based on the data of Lanzhou digital telemetry seismic network(Lanzhou DTSN), using four parameters(rco, Rco,Sco1, Sco2) from three amplitude ratios among some body waves and first motion of seismic wave, which are amplitude ratio of end portion in the wave, amplitude ratio of P and S waves,and amplitude ratio of first motion of P wave and the maximum amplitude of S wave,the anomolies before Jingtai earthquake(MsS. 9) on June 6,2000, Sunan earthquake (Ms 5.3) on July 11,2001, and Xinghai earthquake (Ms6.6) are analyzed and researched. The result shows that each type of amplitude ratio appears high value better moderate-strong earthquakes in 1-4 months, among them parameter Scol and Sco2 have better relation with earthquake. That means,because the frist motion of P wave arrives station first and is not disturbed by other waves,the amplitude ratio of it cna reflect the information of seismogenic region directly.
ZHANG Xiang-hong , YANG Bin , ZHANG Xiang-yang , WANG Ai-guo
2005, 27(3):240-245,F0003.
Abstract:Up to now, there are different views on the length of F201 left lateral strike-slip fault in South of Zhongwei, Ningxia province. Through comparison study on the rapture belt of M7 1/2 South of Zhongwei earthquake in 1709 from eight aspects in this paper,it is ditermined that the length of F201 is at least as same as the rapture length of the South of Zhongwei earthquake in 1709. The earthquake rapture starts from East to Yingpanshui as west end and extends eastward to Shuangjingzi, then expands to nearby Shijuangou at east to Liugangjing, the overall east-west length of the rapture is 110 km. The rapture is composed of five secondary shear faults, Xiaohongshan-- Gushanzi, Xiliangtou-- Yaoxianzigou, Kulongshan-- Jiangou, West to Qingtuoai-- East to Sikouzigou and Shanyangchang--East to Liugangjing.
ZHAO Ming-chun , DIAO Gui-ling , ZHANG Xue-min
2005, 27(3):246-250,254.
Abstract:The Capital Digital Seismic Network, covering Beijing, Tianjin and central Hebei province,has recorded 1186 new earthquakes with M≥1. 0 during May 2002 to Dec. 2003, in which the arrival time differences between longitudinal wave and transverse wave are 2-25 s. Choosing the earthquakes recorded by 5 or above 5 stations, and demanding the epicenters are located in the network or near its edge, we calculate the average velocity ratios in this area. It is thought on the analysis that: (1) The majority of earthquakes are at depth of 8-10 km, after relocating the focus by HYPODD, so the average velocity ratio we obtained can only reflect the state in the upper crust. (2) The average velocity ratios are very steady, whatever in the long time scale or large spatial scale. (3) The reliability of average velocity ratios relies on the number of stations to satisfy the fitting precision. The results from fewer stations are always accompanied by larger errors, and single earthquake with big amplitude of change in average velocity ratio is not suitable to represent the property change of crustal media.
REN Xue-mei , MA He-qing , CHEN Chun-mei
2005, 27(3):251-254.
Abstract:By studying earthquake activity characteristics of M≥5.0 in China mainland (Xinjiang and deep earthquake area in northeast China haven't been included) since 2000, it is found that the case for M≥5.0 earthquakes occurring one after another around the sourec area is significant feature of seismicity in certain regions. Based on this characteristic, the medium term prediction can be made for future earthquakes of M≥5.0 in study area.
QU Yang-jun , WANG Hai-tao , NIE Xiao-hong
2005, 27(3):255-259.
Abstract:By analyzing the relationship between the activity of large earthquakes in Chinese continent and middle-small earthquakes in some special regions and the activity of strong earthquakes in Xinjiang region, it is found that there exists precursor relativity before Ms6.8 Bachu--Jiashi earthquake on Feb. 24,2003,in Xinjiang.
SHI Yu-cheng , MA Er-man , CHEN Yong-ming , FU Chang-hua
2005, 27(3):260-266.
Abstract:Based on field investigation for the building damage caused by Minle--Shandan Ms6. 1 and MsS. 8 earthquakes in 2003, the kinds of buildings are classified and their structure characteristics are discussed. Through analysis the characteristics and the mechanism of damages for each kind of buildings are revealed. Furthermore, experiences and lessons on seismic disaster prevention and reduction in such countriside area are summarized and the management of rural buildings is emphasized.
DENG Jin , WANG Lan-min , ZHANG Zhen-zhong , YUAN Zhong-xia
2005, 27(3):267-271.
Abstract:It is found that the recently accumulated loess in one site at Shuping village , Yongdeng country, Gansu province, has special engineering behaviors. It has larger water collapsibility but only smaller seismic subsidence in natural humidity. Based on the analysis of microstructure images by means of scanning electron microscopy and experimental results of its physical parameters, the micro-mechanism of causing the special engineering behaviors is revealed. Some suggestions for construction on this kind site soil are presented.
HAO Zhen , LIANG Zi-bin , HAO Cheng , MA Zhan-hu , LI Shao-hua
2005, 27(3):272-277.
Abstract:The technological scheme and design method of building Security Firewall of Gansu Seismic Information Network through Netfilter/iptables techniques are introduced. The firewall disposition script of this system is completely showed, and the implementation strategy of every function is detailedly explained. Finally, the advantages and disvantages of netfilter/iptables techniques are objectively analyzed.
CHENG Lan-qing , ZHONG Xin , WU Yong-xin
2005, 27(3):278-281.
Abstract:On June 23, 2000, the water color of Long-07^# observation well in Qingshui county, Gansu province,changed from achromatic to blue suddenly. Using the data of all-around water quality analysis, the hydrogeochemical process and mechanism of the event are studied, and the relation between tectonist activity in margin area of Qinghai--Tibet plateau and the water color changing event before west to Kunlun Mountain Pass Ms 8.1 earthquake is discussed,combining with other anomolies in eastern Gansu province.
2005, 27(3):282-283,286.
Abstract:A super-great earthquake( Ms = 8.7)occurred in Sumatera, Indonesia on Dec. 26,2004. On Oct. 30,2004 the first author of this paper had given a great earthquake prediction: the date is on Dec. 20,2004 with a range of ± 5 days(or ± 10 days) ; the magnitude is Ms=7.5-8.5. Both the predicted date and magnitude are agree well with Indonesia earthquake. The predicted region was mentioned to be in the South Japan, which is far away from the Sumatera region. It is found that Indonesia earthquake and other two super-great earthquakes in Asia are characterized by the informational orderliness of 53-54 years. Therefore,it means that super-great earthquakes in Asia are possible to be predicted.
DANG Hong , HAO Zhen , LI Chun-ling
2005, 27(3):284-286.
Abstract:The seismic location results for 100 earthquakes events with 2.0≤ML≤4. 3 from Jan. 1, to Oct. 31, 2002,recorded by Lanzhou District Digital Telemetered seismic network, using 3 defferent locating program Hypo81,Gentic and Nearloc,is analyzed and compared. The result shows that the locating effectiveness of Nearloc program is obviously better than other two programs. Nearloc has good locating effectiveness for events which took place both inside the network and outside edge of the network to 1,000 km,so it can be used widely.
Sopyright:China Earthquake Engineering Journal