SUN?Rui , YUAN?Xiao-ming , CHEN?Hong-juan
2010, 32(3):209-214.
Abstract:The dynamic shear modulus ratio and damping ratio are the necessary parameters for analysis of ground motion, seismic safety evaluation of engineering sites, and seismic microzonation. But the uncer- tainty of two parameters is great and have remarkable effects on the ground motion and design spectrum. In this paper, basing on the testing results of nonlinear relationship between shear strain and dynamic shear modulus ratio, damping ratio for conventional soils, the calculation method of their exceedance probabilities is presented. The method includes the statistics of testing data, calculation of the ex- ceedance probability and the curve fitting process. The calculation equation for the exceedance probabili- ties of the dynamic shear modulus ratio and damping ratio are proposed and the results may lay the foun- dation for seismic safety risk assessment basing on probability and reliability theory.
YANG?Bo , ZHOU?Wei , CHEN?Fu-chao , HAN?Yue-ping
2010, 32(3):215-219,225.
Abstract:The research on crustal deformation especially in active fault zone using GPS technique and the related data processing method for earthquake prediction are now not perfect and enough. Aimed at this problem and for actual work requirement, the data processing method for the chara-cteristic analysis of crustal deformation in fault zone is suggested from field view in the paper. Based on the GPS data from Sichuan - Yunnan region in 1999 - 2004, the crustal movement characters in eastern boundary fault zone of Sichuan - Yunnan block are analyzed by using this method. The results show as follows : ( 1 ) The rela- tive movement and spatial variation in both sides of the fault zone can be shown clearly in different view angles by this data processing method. ( 2 ) The deformation width on both sides of the fault zone is about 400 km with the maximum movement value of 15 mm/a. However, 2/3 of the movement distribute in a belt area about 100 km width along the faults. This clearly shows the distribution of slip movement and shearing strain accumulation from the motion isogram. (3) The deformation on southern part is more than that on northern part of Eastern boundary zone of Sichuan - Yunnan Block showed by the gradient varia- tion map of slip movement. (4 ) In perpendicular direction to the fault there is not clearly different de- formation between two sides of the zone.
CAI?Han-cheng , YAN?Zhi-xin , WANG?Qun-min , LIANG?Xiao-bo
2010, 32(3):220-225.
Abstract:Numerical analysis of the dynamic response for rock-soil mass slope under different traffic loads is made, using numerical analysis of geoteehnical software FLAC2D6.0. The result indicates that under traffic loads, the vibration acceleration of rock-soil mass near seismic source is the maximum, up along slope or inner slope in horizontal direction it decreases gradually. Near seismic source , the vibration at- tenuation is more intense, and it gets more weak as distance increases. The heavier the traffic load is the bigger the attenuating range is. Above the road the vertieal acceleration and the horizontal acceleration in slope are in same magnitude, and the vertical one is bigger than the horizontal one. The magnitude below the road is bigger than one above the road, the vertical acceleration and the horizontal acceleration are in same magnitude, and the horizontal one is bigger than the vertical one also. The results have some theo- retical significance and project application for evaluating the influence acting of traffic loads on rock-soil mass slope and considering how to reinforce and govern the slope under traffic loads.
2010, 32(3):226-230.
Abstract:Time-lapse seismology is an advanced geophysical technology which is called 4-D seismology in recent years. In this paper, some key technologies are analyzed, the concept and concrete data structure of flow-units in time-lapse seismology are given. Simultaneously, the way how to increase interpretation points on sections and slices during flow-units interpretations are discussed detailedly. The treatment effects are shown based on an actual example also.
LI?Xia , DONG?Xiang , LIU?Xi-qiang , MIAO?Qing-jie
2010, 32(3):231-236.
Abstract:The ratio of observed spectral amplitudes of direct P and S wave phases is linearly correlated with the ratio of their radiation pattern factors, and the radiation pattern factor depend on geometrical property of focal mechanism, if 2 events occurred in same focal region and recorded by same seismic sta- tion. Using low-frequency spectral amplitude values the correlation coefficient can be calculated, and the eoeffieent gives a normalized measurement for the similarity of focal mechanisms. Applying this method to the Qingdao earthquake sequence in 2003 and the small earthquake concentrating area in conjactive area of Hebei, Shandong and Henan provinces, the events with similar focal mechanism can be grouped, and the temporal average correlation coefficient curve of earthquake sequence can be obtained. The results show: the temporal average correlation coefficient curve of Qingdao earthquake sequence is changed from centralizing to scattering pattern, namely stress strength in focal area was transform from comparatively concentrating to separating; but the coefficient for conjactive area of Hebei, Shandong and Henan was poorer, regional stress concentration is not formed one dominant diraction.
LIU?Xiao-feng , ZHANG?Hui , MEI Xiu-ping , ZHENG?Wei-ping
2010, 32(3):237-243,291.
Abstract:According to seismic activity and precursor anomaly characteristics of mid-strong earthquakes in southeast area of Gansu province, the forecasting index systems for determing seismic time, site and intensity are confirmed separately, and the prediction efficiencies of each index are evaluated. Based on this work, we constitute scheme of M5 -6 earthquake medium-short term prediction in this area. Then using level analysis, early warning index system model of seismic situation about M5 earthquakes is en- sured. On the basis of the early warning model and leveled index, we translate all qualitative and quanti- tative index into non-dimensional parameters with 1 - 4, get importance of comparing substrate two adja- cent targets to a upper layer target using paired comparison, calculate cell weight vector, and check up the coherence of model's whole levels. The results show that the early warning value of M5 earthquake is 3.11 in the area, and by classification standards of early warning scale, early warning lever of seismic situation is red as if each forecasting index be satisfied.
GUO?Xiao , ZHANG?Yuan-sheng , HE?Bin
2010, 32(3):244-247.
Abstract:On the base of micro-earthquake seismogram records of Lanzhou temporary digital micro-earth- quake network, and a presumed trilinear geometrical spreading model, the inelastic attenuation Q value is investigated by using genetic algorithm and the method proposed by Atkinson. The frequency-dependent of inelastic attenuation Q value in Lanzhou City and adjacent regions is estimated as Q (f) = 45. 1f1.488. And the result is discussed and analyzed with the results from other regions.
2010, 32(3):248-252.
Abstract:Earthquake disaster is one of the most serious disasters, which may result in heavy ca-sualty and economic loss. Earthquake insurance has become the important way to manage significant disastrous risk in developed countries. Among them, the manage model of earthquake insu-ranee in Japan has its distinguishing feature. But in China, as a socialized system for disaster loss allocation, insurance has not played its constructive role. In this paper, the allocation mechanism of earthquake disaster loss and earth- quake insurance model in Japan are introduced. The current allocation mechanism of earthquake disaster loss in China is analyzed also. Learning Japan's experience as reference, the suggestion for constructing China's earthquake risks transfer mode is presented, it should include the role of government, the devel- opment of insurance market and the idea of calamity-stricken people.
2010, 32(3):253-257.
Abstract:Through consulting and analyzing historical documents and materials, comparing the destructive situations in different historical earthquakes with similar magnitudes at same place, considering the wider destruction range, we think that the magnitude assessment for Daguan Jilipu earthquake on July 31,1917 in Yunnan province in each versions of 《 China earthquake catalogue》 may be on the low side, and mag- nitude = 71 /4 is more appropriate, which tallies with the main data recorded by instruments, conforms to the rear situation of earthquake disaster, can explain the basis of earthquake magnitude source better. New magnitude is of important significance to the reasonable estimation of seismic risk degree of Daguan - Yongshan - Leibo - Mabian seismic belt.
LEI?Zhong-sheng , YUAN?Dao-yang , ZHANG?Jun-ling , LIU?Bai-chi , GU?Yan
2010, 32(3):258-263.
Abstract:During the period of textual research on the historical earthquake data and field investigation in Minqin region of Gansu province, new six moderate-strong historical earthquakes were found in the book of named 《Annals of previous incidents in Zhenfan county》. By comprehensive analysis and comparison, the basic parameters of each earthquake are simply determined. The works provides new data to analyses of seismic-tectonic activity in Minqin region.
XIA?Yu-sheng , MA?Zhen , LI?Tao , CUI?Guo-xin
2010, 32(3):264-267.
Abstract:The data of 100 earthquakes with Ms ≥ 5.0 recorded by all kinds of instrument in seismic sta- tions in Qinghai province are examined, among them the true earthquake precursor waves are determined. The short-impending precursor characteristics of the waves are analyzed. Some problems in short-impend- ing earthquake forecast by earthquake precursor waves are discussed.
ZHANG?Yong-liang , CHEN?Xing-chong , XIA?Xiu-shen
2010, 32(3):268-272.
Abstract:The large mass method for simulating ground motion is introduced, the model and equations used for considering the seismic effects of traveling wave on long-span bridge are derived. Taking Dazhun great bridge on Yellow river as an example, considering such main parameters as pier shaft stiffness, earthquake wave speed and different ground acceleration time-history, the seismic response of railway long-span continuous rigid-frame bridge under excitation of traveling waves is analyzed, and the compara- tive analysis of the results with uniform excitation are made also. The characteristics of seismic response on the bridge are systematically summarized. The analysis method and results in the paper are of certain reference to the design and research of similar bridges.
ZHANG?Hui , ZHANG?Xin-ji , SU?He-jun , LIU?Xu-zhou
2010, 32(3):273-278.
Abstract:Concentrations of radon and mercury in soil gas which were obtained on the main active faults in Lanzhou city are measured. The sample points were selected at the site where the outcrop of fault exists or there are borehole data. The result shows that not only the peak-value anomalies of radon and mercury in soil gas on the active fault show obviously, but also their shape characters reflect the fault location, fault property, and fault attitude well. It is proved that gas survey is a useful method for active fault ex- ploring and study. The result shows also that the shape and characteristics of peak-value anomaly of radon and mercury concentrations in soil gas on fault zone are affected by the overburden thickness.
2010, 32(3):279-285.
Abstract:There are four types of seismic quiescence: Non-earthquake quiescence and quiescence after- earthquake are regarded as non-precursor quiescence, quiescence before earthquake and field-precursor quiescence are precursor quiescence. In this paper, the seismic quiescence phenomena in the both east- ern and western part of southern Tianshan seismic belt are statistically divided in different types, the characteristics of the quiescence and relationship with mainshoch are analyzed. Research on the characters for different seismic quiescence level is helpful for judging the magnitude and position of future earthquake.
2010, 32(3):286-291.
Abstract:The quick-change in observing values of radon is a main base for short-impending earthquake prediction. Through analysis on the quick-changes of radon from 17 stations in Gansu province, it is found that the genesises of quick-change of radon are mainly disturb factors such as temperature, rainfall, water flow, apparatus et al. and earthquake. At 5 stations, most of radon quick-changes ( ≥ 50%) caused by disturb factors, and at other 12 stations most genesises are unacquainted. Except the Li- ancheng station, the quick-changes of radon have not obvious relationship with earthquake events at sin- gle station. But analysis on the group chick-changes in divided two regions shows that earthquake will maybe occur after the number of quick-change points being 5 in a month and increasing gradually in southeastern Gansu l~rovince. For Qilian mountain region, there was not this character.
HUANG?He , LIAO?Xu , ZHAO?Bo-ming
2010, 32(3):292-299.
Abstract:The current models and the computational method used in the active fault earthquake hazardous forecasting in Shenyang area are introduced briefly, and the forecast results in different earthquake scales are given and analyzed. The results are compared with the present result of seismic safety evaluation and the national seismic motion parameter regionalization map. The corresponding exploitation conditions and some suggests are presented also.
QIN?Jian-zeng , LI?De-qing , XIE?Ru-yi , FENG?Jian-lin , ZHANG?Rui-min
2010, 32(3):300-306.
Abstract:The variation features of gravity field and seismicity before and after the Fengqiu earthquake swarm are discussed based on the data of gravity monitoring network in border region of Hebei - Henan - Shandong provinces. The results show that the ascent→descent→ascent variations of the gravity field before the earthquake are the obvious reflection of medium-short-term anomalies in the gravity field, and the earthquake occurred during changing stage of acceleration. The dynamic images reflect clearly the evolu- tionary process of the gravity field in the seismogenic zone, i.e. quasi-homogeneous state→inhomoge-neous state→earthquake occurrence. After the earthquakes, the gravity anomalies in this region did not recover. The prediction of Fengqiu earthquake according to the gravity anomalies is presented in the paper also.
DAI?Wei , YAN?Wu-jian , MA?Zhan-hu
2010, 32(3):307-312.
Abstract:A moderate earthquake (Ms5.0) occurred on 30 March 2008 in Huangcheng town, Sunan county, Gansu province. The principal parameters and sequence character of the event are summarized, the earthquake focal mechanism is inversed with P motion, and distribution of the seismic damage is ana- lyzed based on the date of the field investigation. The tectonic background of the event is discussed in the views of regional tectonics, seismic activities, focal mechanism, distribution of aftershocks and the major axis of epicenter area, but the result shows that the causative structure is not clear.
Sopyright:China Earthquake Engineering Journal