LIU Tian-ming , SU Rui , ZHANG Bo-hong
2001, 23(3):217-223,237.
Abstract:The 4D model is used to invert dynamic variation for crustal density and vertical deformation from the data of gravity measurement and leveling survey.The inverse formulae are derived.Using the formulae, data of gravity measurement and leveling survey in the Hexi region of Gansu province and northwestern Yunnan province are computed, for study on variations of the lower crustal interface density and vertical deformation of Moho surface with time.Relationship between the variations and moderate-strong earthquakes in the two regions is analysed.The results show that density of lower crustal interface reduced on a large scale and upheaval of a wide range of Moho surface in the two regions may be a geophysical criterion in crustal depth for earthquake prediction in one year.Strong earthquakes often occur in regions that are located between upheaval and subsidence of the Moho surface or density reduction and density increase of the interface.
LIU Wen long , WANG Jin zhou , CHEN Yu wei , LING Xue shu , HE Xiao wei , LIU Dong wang
2001, 23(3):224-229.
Abstract:The errors of determining direction of fracture plane and environment stress of moderate and small earthquakes are analyzed in detail.The result shows that the main factors causing the error of determining direction of fracture plane are the field angle in which the stations are distributed and the precision of making the theoretical master for the generalized directional function.If the theoretical curve is given for every 15°of θ, then the error can be less than 15°when the field angle is more than 60°.The main factor creating the relative error of the environment stress τ0 is the magnitude error.If the magnitude error is 0.3,it may cause the relative error of the τ0 to reach 70%
2001, 23(3):230-237.
Abstract:By using the seismic source model of crack containing hyperpressure gas, the course of radioactive heat energy in the earth to accumulate in the focal area and cause for earthquake are studied.The mechanical models are given.The quantitative analyses on transformation of elastic and displacement potential energies of the rock and heat energy of the gas in source area into seismic energy are made.The formulas between magnitude and focal size, deformation, seismic moments and seismogenic period are derived.The formulas tally with that of other men of learning and real earthquakes.The seismic source model of crack containing hyperpressure gas is verified further by energy.
2001, 23(3):238-242.
Abstract:The relation between discharge changes of Ligou well, Qingshui and Shiqiao well, Lixian and mid-strong earthquakes in neighboring region is analyzed.It is found that discharges of the two wells rise or undulate about half of year before part of the mid-strong earthquakes in the neighboring region, with a maximum anomalous amplitude of 3.75mL/s.There are no the anomalies of the discharges before the events with smaller magnitude relatively distant from the wells.The reflecting range of the anomalies of the two wells to MS5 events is 250 km, that to MS6 events is 350 km and that to MS7 events is 500km.
YANG Li-ming , XIAO Li-zhu , ZHANG Xiao-mei , YIN Zhi-gang
2001, 23(3):243-249.
Abstract:The main conclusions of the study on the seismicity tendency by other men of learning are review ed briefly, and the main behaviors of the seismicity in time and space are obtained. Meanwhile, the tendency of seismicity in northern Qinghai-Tibet plateau is analyzed systematically.There are 6 active periods and 6 quiet periods of seismicity in the region in the 20th centenary, not synchronizing with that of the continent of China.A new active period for earthquake begins by the Jingtai MS 5.9 earthquake on June 6, 2000 and the Xinghai MS 6.6 earthquake on Sept. 12, 2000.
CHEN Yu-hua , MA Wen-jing , ZHANG Rui-bin
2001, 23(3):250-256.
Abstract:Sequences of 65 MS ≥ 5 earthquakes from 1970 to 1999 in Qinghai province and its vicinity are analyzed and studied.These sequences can be divided into isolated type, mainshock-aftershock type, foreshock-mainshock-aftershock type and multishock type, in which isolated type is the most.There are 18 MS ≥ 6.0 sequences in which mainshock-aftershock type is the most in the 65 sequences.The sequences are distributed in Qilian, Chaidamu, Kekexili and Wulanwulahu seismic belts.Earthquake frequency, strength and sequence type in the four seismic belts are analyzed. Characteristic parameters of early days of the seismic sequences are calculated.The results show that b and u values are useful in early discrimination of seismic sequence type.
2001, 23(3):256-256.
Abstract:沙漠主要是由于气候干燥而形成的.在干燥的气候条件下,遇到强烈的大风,天气就容易形成沙尘暴.大地震在地表造成的岩石、土层破裂和沙土颗粒粘聚性的破坏加剧了地表的沙漠化,为沙尘暴的形成进一步提供了物质来源.
LI Ying , CHAI Chi-zhang , ZHAO Wei-ming , REN Xue-mei , KANG Ling-yan
2001, 23(3):257-260.
Abstract:Anomalous variations of water level of Ganyanchi and Wang min wells in southern Ningxia before the Jingtai MS6.2 (1990)and MS5.9 (2000)earthquakes in Gansu are analyzed. It is found that the variations of the two wells have shows of trend and medium-term or short term anomalies before the two earthquakes.The medium-termor short-term anomalies of Ganyanchi well show that regularity of annual variation of the water level is broken and the anomalies of Wangmin well show that water level dropped evidently.The anomalies of the two wells are synchronous with the repetitive feature.
2001, 23(3):261-264.
Abstract:The half year and month anomalous frequency velocity rates of ground fluids before the Baotou MS 6.4 earthquake on May 3, 1996 are studied.Effects of the half year and month anomalous frequency velocity rate methods are tested.The results show that the seven items have medium term anomaly shows and five items have short term anomaly shows among nine observation items.The identification rates for anomalies by the two methods are better than that by the original patterns.
LI Qiang , XU Gui-ming , FAN Gui-ying
2001, 23(3):265-268.
Abstract:The end-time of the recent earthquake active episode and future earthquake tendency for seismic zone from mid-lower reaches of the Yangtze river to south Yellow sea are studied with the grey theory.The result shows that the end-time of the episode is about 2019 year.The conclusions obtained can be taken for reference in analysis of earthquake tendency and medium-term prediction of earthquake of east China.
MA Shu-qin , GONG Shao-jing , LI Lian-di , QI Cheng-zhu
2001, 23(3):269-273.
Abstract:Single station site effect evaluation method is studied using seismograms obtained by strong motion observation array in Tangshan.Using rock station in bore hole as reference station, empirical transfer function is calculated with seismograms of both surface and borehole.Simultaneously, the Nakamura spectral ratio is calculated with surface seismograms.The results by the two ways are compared and it is confirmed that the single station method is encouraging.The method can be applied in site effect evaluation for important buildings as a simple, executable method.
HU Wei-jian , ZHANG Jun-shan , ZHOU Xiao-chuan , XIE Zhi , WANG Zhi-min , LI An-yin , LI Ping-lin , XIE Jianjian , LIU Li-jun
2001, 23(3):274-278.
Abstract:An earthquake (ML=4.2)occurred in the boundary area between Xinyang, Henan and Suizhou, Hubei on January 28, 2000.Xinyang seismic station is located on northeast of the epicenter with a distance of 35 km and in the same fault with the source.Several kinds of medium short term and impending earthquake anomalies of the fixed crust deformation are recorded in the station before the event.The study results indicate that variations of the observation values before the event are larger.The observation values of EW by water tube tiltmeter changed in reverse from June, 1999 and changed acceleratively three days before the event.The values of NS by the meter changed acceleratively from M arch, 1999 and jumped suddenly 5~8 days before the event. The values of EW and NS by horizontal pendulum tiltmeter changed in reverse respectively from February and June, 1999 and fluctuated quasi-periodically about 20 days before the event.Moreover, the obvious anomalies of the deformation tide factor from the station arised too before the event.
CHEN Jun-ying , LIN Chang-you , WANG Shu-ming , YANG Chang-fu
2001, 23(3):279-285.
Abstract:The joint inversion effects by multi-parameter of apparent resistivity from the frequency electromagnetic sounding with electric dipole supply (FEMS)are tested by using H and K models and numerical simulation.The results show that the inversion effects are better and have quicker convergent rate and higher fitting accuracy.
2001, 23(3):286-290.
Abstract:The dynamic characteristics of loess in Irkutsk, Russia are studied by using the dynamic triaxial test.The dynamic parameters of the loess are obtained.The results show that the stressstrain relationship obeys the hyperbolic model and the G/GO~γd curves have good normalization character.It is found that the main factor that influences the shock settlement of the loess in Irkutsk is moisture content.
ZHANG Shi-zhong , ZHAO Jia-liu , WANG Yan-qiong
2001, 23(3):291-296.
Abstract:Analyzing reasons for system errors in measurement of earth resistivity, several methods to remove the errors are proposed.It's believed that the system errors are influenced by the accuracy of setting coefficient K, sampling resistor RI and measured ΔV and VRI.The RI with high precision and stability is chosen, the "suspending" measurement is applied and the same A/D converter with wide dynamic range and high linearity is used to measure ΔV and VRI in developed terrameter by the authors for decrease of the system errors.At last, effect of the "suspending" measurement is verified by test in laboratory.
WANG Shu-ming , LIN Chang-you , CHEN Jun-ying
2001, 23(3):297-300.
Abstract:The magnetotelluric(M T)monitoring results for seismicity after the Jingtai MS 5.9 on June 6, 2000, Gansu province are introduced.Changes of apparent resistivity with time in the monitoring period are analyzed.It is believed that it is improbable that stonger earthquakes should occur after the Jingtai earthquake according to smaller variations and repeated character in range of error of observed apparent resistivity with time.The judgement result is identical with reality.
2001, 23(3):301-304.
Abstract:The interferential factors which influence quality of data and excluding methods in remote measurement of radon in Xiwudang spring are studied by prectical observation and a series of tests.It is found that the electricity supply system has main influence on stability of observation instrument.That installation of separation gas is normal or not is another factor influencing quality of observation data of radon.Increase of power of electricity supply system and heat preservation for installation of separation gas are effective methods guaranteeing observation data quality of radon in the spring.
2001, 23(3):304-304.
Abstract:200 1年7月11日05时41分3.8秒,甘肃省镜铁山发生了MS5.4地震。经甘肃省地震监测台网测定,该次地震震中位于39.2°N,98.0°E,震源深度10 km。
2001, 23(3):305-307.
Abstract:The seismically active degree S value that can quantitatively describe strong-weak level of seismicity is used to study seismicity characteristics of east and west sections of southern Tianshan in Xinjiang.It is found that seismicities of the two sections are closely correlative, and earthquakes migrate from the west section to the east section.The seismicity of the east section is behind that of the west section for one year or so.It is believed that the above-mentioned characteristics can be applied in earthquake prediction of southern Tianshan.The push and extrusion of the Pamirs block towards NE direction from the Indian plate may be dynamical source of seismicity in southern Tianshan.
GUO Yu-lian , TANG Ting-mei , TONG Rui-qing
2001, 23(3):308-309.
Abstract:1996年渤海及周围地区被划定为地震重点危险区,为了加强地震监测工作,山东省地震局购置了3台由深圳华隆地球物理仪器工贸公司(中美合资)组装的G-856质子旋进磁力仪。
2001, 23(3):310-312.
Abstract:Analysing thermal infrared anomaly images before earthquakes more than 40 in China and its neighboring areas, the main features of the infrared anomalies are summarized.In general, there exist clearer anomalies with a bigger amplitude of temperature increase which show the character of suddenness and phase before MS >5 earthquakes.Abnormal area is related positively to magnitude with a certain degree.Some studies on mechanism of the infrared anomaly are introduced and the author's trend opinion is put for ward.It is believed that the polarizing function of air static electric field anomaly to the atmosphere impending before earthquake should be the major factor to the infrared anomaly.And "the greenhouse effect" of the atmosphere containning abundant "polluting air" should be another factor that can not be ignored.
Sopyright:China Earthquake Engineering Journal