LIU?Xi-qiang , ZHOU?Yan-wen , LI?Hong , WANG?Mei , SHI?Yu-yan , ZHANG?Kun
2007, 29(3):201-206,212.
Abstract:The test results for emulative signal indicate that the time delay estimation method Of bispectrum has the capacity to suppress Gauss noise and can accurately estimate the time delay of signals. Compared with Fourier transform method, the spectrum power reconstruction method of bispectrum has higher accuracy and capability. The research results show that the characteristic parameter distribution of bispectrum has a good consistent characteristics to the normal earthquake precursory monitoring data, but has a obvious dispersion characteristics to the abnormal data, which indicats that bispectrum has the discrimination capability to earthquake precursory anomalies in monitoring data.
ZHOU?Jing , CAI?Jian , FANG?Xiao-dan
2007, 29(3):207-212.
Abstract:Augmenting the flexural strength of columns in the seismic design of reinforced concrete (RC) moment resisting frames is a key measure among all the detailing procedures of capacity design, which induces the desirable beam sidesway mechanism for the structure to dissipate energy during a strong earthquake. The objective of this paper is to assess the influence of various strong column factors which is employed to perform seismic fragility analysis to the seismic performance of a 6-storey deterministic RC frame structure. Seismic fragility analyses indicate that augmenting the flexural strength of columns is an effective measure to improve seismic performance of RC frame structures. Increasing strong column factor improves the displacement capacity of structure and induces the biggish grads between the different damage limit states, which provide caution to prevent the abrupt collapse of structure during a strong earthquake. Seismic fragility curves provide the quantitative criterion for evaluating the seismic performance of structure and choosing appropriate target strong column factor.
GAO?Li-xin , LIU?Fang , ZHAO?Meng-sheng , YU?Hong-mei
2007, 29(3):213-217,244.
Abstract:The method using arrival-time difference between sPn and Pn phase of seismic wave to determine the depth of seismic resource in near region within crust is simple and accurate. In this paper, the sPn phase of Dongwuzhumuqin MS. 9 earthquake on March 24,2004, recorded by different seismic stations their epicentral distances are no more than 1 000 km in Inner Mongolia Autonomous Region are primary analyzed, and the depth of event focal is calculated. Meanwhile the possibility that using sPn phase to determine depth of seismic resource and application of this method to daily earthquake monitoring work are discussed.
ZHANG?Xiao-tao , HAN?Li-ping , LV?Feng-zhang , MA?Guang-qing , SUN?Qing , JIN?Yu-ke
2007, 29(3):218-223.
Abstract:Using the Sato single isotropie scattering model and the near-field digital seismic records from Hongshan seismostation in Hebei province, the variation characteristics of S-code Qc value in Xingtai seismic region are studied. The relationship between the Qc value and frequency is ob- tained: while the length of windows are 15-30 s, Qc= (42.9±20.7)f^(0.98±0.13) ,and while the length of windows are 40 - 60 s, Qc = ( 103.1±27.9 ) f^(0.85±0.08). Through analyzing the variation curves of Qc along with time in different frequency point, it is found that before Longyao Mt. 5.0 earthquake on April 22, 2002, in Xingtai seismic region, the high-frequency part of Qc value changed as "increasing→reducing→re-elevating→shocking" pattern, and this pattern has certain referent significance for moderate-strong earthquake prediction in Xingtai area. It is also found in the research that comparing with Aki model, the Sato model is better for the S-code computation and analysis in Xingtai seismic region.
2007, 29(3):224-229.
Abstract:In usual different filter methods are selected according to the differences between effective signal and noise for increasing the signal-noise ratio. But for complication of seismic data, sometime the effective signal and noise have no clear difference in apparent velocity and frequency. For this problem a method using S transform to fulfill the time-frequency filtering is presented in this paper, and the advantage of S transform in time-frequency filtering is compared with other filter methods through example.
2007, 29(3):230-234,297.
Abstract:Using the finite element numerical simulation method with the plate tectonic boundary conditions and the characteristics of inner plate tectonic distribution, the basic tectonic stress field of eastern Chinese mainland is simulated. According to the effect situation from adjacent plates, influence of the acting force change on plate boundary to inner stress field of eastern Chinese mainland is analyzed. Comparing with the simulated result, the characteristics of seismic activity for space distribution in eastern Chinese mainland are expounded.
ZHANG?Bin , YANG?Xuan-hui , YI?Zhi-gang
2007, 29(3):235-239.
Abstract:The distribution and space-time change characteristics of the seismic apparent strain field in Songpan-Pingwu and the adjacent areas since 1970 to 1975 are studied, using the seismic data of this region. The result shows that there is a rather well corresponding relationship between the anomalous region of seismic apparent strain and the Songpan-Pingwu earthquakes in 1976. The anomalous region appeared in 1970 vents occurred just in the anomalous region.
XU?Shun-hua , QIU?Ren-dong , WANG?Ping
2007, 29(3):240-244.
Abstract:The experimental formula for boundary depth of loessial seismic subsidence in Lanzhou and Xi'an areas is acquired by using the data of seismic micro-zone in both cities, and the result is identical with the test result. It is indicated that the characters of loessial seismic subsidence can be reflected better by physic parameters of loess, such as water contents, concretion stress, shear wave velocity, under certain dynamic condition, and the boundary depth can be predicted by studying relationship between them and residual strain.
GUO?An-ning , CHEN?Jia-chao , GUO?Zeng-jian
2007, 29(3):245-247.
Abstract:Temporal distributions of infrared anomaly before great earthquakes( ±Ms8.0)in China and adjacent regions in recent years are analyzed. It is found that they accord with the multiplied nine days regularity. In this paper this regularity is discussed based on the model of modulation and triggering of external factor. It is also considered that determining the epicenter of future earthquake in infrared anomaly area can refer the position of very high peak.
LU?Peng , LIU?Rui-feng , LI?Zhi-xiong , CHEN?Hua-jing , WANG?Song
2007, 29(3):248-251,255.
Abstract:The principles of classification and grade of seismological science data for sharing are discussed based on the analyzing situation of the data. According to the scientific nature and sharability of seismological science data, they are classified and graded preliminarily. The results can be used as reference for sharing the seismological data.
HE?Xin-she , LEI?Zhong-sheng , LI?Shao-hua
2007, 29(3):252-255.
Abstract:The earthquake happened in Dingxi and Huining county on April 26,1352, was one of the strongest earthquake in center of Gansu province. Because of the shortage of historical documents it has been not clearly recognized for a long time. In recent years, during the collecting of the historical data and investigation in the field, many new discoveries for this event were gotten, which provide a valuable historical basis for researching the earthquake.
MA?Zhan-hu , ZHOU?Zhi-yu , GAO?Xiao-ming , HE?Wen-gui , LIU?Hong-chun
2007, 29(3):256-259,263.
Abstract:On June 21,2006, a destructive Ms5. 0 earthquake occurred at Wenxian, Gansu province, which caused damage to buildings and casualties. In the investigation of seismic field and assessment of earthquake disaster after the event, the disaster area is divided into 2 parts, and the investigation work for 29 sampling spots are finished. According to the loss assessment system of seismic disaster EDLES2.5, a database is set up, and a relatively practical assessment of economic loss is done. Finally, some advices for restoration in earthquake area are put forward.
LIAN?Yu-ping , ZHANG?Jin-fu , LIN?Song-jian , CHEN?Wei
2007, 29(3):260-263.
Abstract:Using the high-resolution shallow seismic reflection, a buried fault in the site of thermal power plant in Fujian province is explored. The result reveal that the fault exists clearly with strike of N40-50°E. It is a normal fault with about 2-4 m throw, and its two breakpoints are buried in 11 m and 31 m depth. The shallow seismic exploration and geological interpretation offer dependable basis for engineering avoidance
2007, 29(3):264-266.
Abstract:A new historical record about southern Wudu M8.0 great earthquake on July 1,1879, was found on the girder of Tianchi Temple in Yangtangzhai village of Wenxian county, Gansu province, in 1985. This record indicates that the seismic intensity here in the earthquake reached × degree.
LI?Hua , HUANG?Li-jing , XU?Yi-xi
2007, 29(3):267-270,274.
Abstract:Using the method of geomagnetic annual difference, the anomalies in data of mobile geomagnetic survey in April, 2006, in west area of Fujian province are ideatified. It is considered that the anomalies are relate to the increasing of the regional stress field before M4.9 and M4.7 earthquakes in Shunchang county, Fu)ian province. It is also found that the anomalies synchronistically occurred in the stations which distribute along a fault before the earthquakes. It is possible that the phenomena is relate to the stress centralizing in some structure parts.
DU?Chang-ting , LI?Wen-qiao , LU?Ning , HA?Hui , CAI?Zha-xi , DA?Jie
2007, 29(3):271-274.
Abstract:Three earthquakes with Ms5. 0,Ms5. 6 and Ms5. 4 occurred on July 18 , 19,2006, in Yushu prefecture of Qinghai province. In this paper the event is determined as a earthquake swarm based on the waveforms recorded by Yushu seismic station and monitoring result from Digital Seismic Monitoring Network of Qinghai province. Synthesizing the seismic intensity isogram, distribution of aftershocks, focus mechanism and regional tectonics, the seismogenic fault of this earthquake is considered as Wulanwula lake-Yushu structure belt.
2007, 29(3):275-278,292.
Abstract:The domestic and international recent mechanism, and the forecast and monitoring for pecially focus on the land subsidence in Shanghai along with the city construction in large scale in situation of land subsidence, the causes, the land subsidence are introduced systemically, escaused by engineering and environmental effects recent years
GAO?Xiao-qi , LIU?Yao-wei , LU?Ming-yong , WANG?Qiong , YANG?Xiao-fang , ZHU?Cheng-ying , CHEN?Ling , LI?Yan-ping , LI?Xin-yong , XU?Qiu-long , SHI?Jie , GUO?Wei-ying
2007, 29(3):279-285.
Abstract:Kazakhstan is one of the country which earliest engaged in the researching precursor of seismic underground fluid. In this paper the developing history and present situation of seismic underground fluid monitoring in Kazakhstan are introduced. It is also compared that this work in Kazakhstan and in Chinese Xinjiang area. The advantages in both side are analyzed at last.
ZHOU?Hao , ZHENG?Zhao-fu , CHENG?Ke
2007, 29(3):286-288.
Abstract:The realization process of long-distance storage for simulant seismic precursor data is introduced, and the corresponding example regulation is given also.
WEI?Huan , DENG?Bai-chang , YU?Li-ye , ZHONG?Pu-yu , WANG?Feng-ji
2007, 29(3):289-292.
Abstract:Based on the processed observation data of geoelectrical resistivity from Heze and Tancheng stations in Shandong province, the characteristics of precursor anomaly of geoelectrical resistivity anisotropy values are researched. The result indicates that there are obvious precursor anomalies of the anisotropy in both stations before M ≥5 earthquakes occurring in range of 300 km, and the anisotropy values change in a stable variation range near the high value. Meanwhile the physical mechanism of this phenomena is discussed.
DAI?Wei , CHEN?Li-qiong , YAN?Wu-jian
2007, 29(3):293-295.
Abstract:In the earthquake sequence of Wenxian Ms5. 0 event on Jun. 21,2006, in Gansu province, the aftershocks were rich, so the type of shock is mainshock-aftershock sequence. No moderate or strong earthquakes occurred in 100 years before the event, but ML ≥3.0 events had increased and occurred one after another with groups in one year before the mainshock. Until one month before, the seismic activity went quiet. No seismic gap and belt is formed.
Sopyright:China Earthquake Engineering Journal