Abstract:The direct integration method to enhance the calculation accuracy of electromagnetic responses for current dipole source over layered earth is discussed. In the method Hankel integration in frequency domain is divided into several partial ones and are evaluated with the method which combines Gauss quadrature rule and continued fraction. The utility of continuous fraction can speed up the convergence greatly. Using the method the electromagnetic responses for half-space and two-layered earth models are tested. Compared with traditional numerical filter method, the result shows that the direct integration technique can improve the frequency response simulation accuracy of electromagnetic soundings for 1D earth, and gives calculating base of obtaining the very late time electromagonetic responses with high accuracy.

Abstract:Ground barrier sy stem for isolating vibration is a geotechnical engineering method used to impede or change wave propagating into protected zone. Because limited research on mechanism of the barrier, the failures of the barrier occur sometime in prectice. In this paper the theoretical analysis of soil and barrier system for isolating vibration is presented, in which the barrier is assumed to be an elastic plate of medium thickness embedded in elastic soil; and the thin layer method (TLM) is employed to examine dynamic response of the plate and ground vibration in protected zone under an incident wave. Some key parameters that influence the effect of barrier for isolating vibration are analyzed. A phenomenon of the wave completely thransmiting through the barrier and causing failur of the barrier is found, and a circular frequency of the complete wave transmission is defined to explain this phenomenon. The theoretical result shows that the complete wave transmission occurs more easily in flexible barrier system than in rigid one. At the end the recommendation for improving barrier design to avoid failure is presented.

Abstract:In order to extract the difference information from the recorded waveforms of natureral earthquake and explosion or collapse in seismic focus depth, seismic focus scale, seismic focus break mechanism, seismic wave travel path and seismic wave attenuation, the energy linearity characteristics of wavelet multiresolution from the records of some nature earthquakes, explosions and collapses in Digital Seismic Network of Shangdong prov. are analysed, and a new method of energy linearity in wavelet transform is put forward to distinguish explosion or collapse from nature earthquake. The result indicates that in energy linearity of fine structure wavelet decomposition signal, the range of nature earthquake is from -2.0 to 1.0, but the range of explosion or collapse is from 2.0 to 3.4; in wavelet decomposition scale corresponding to maximum energy of fine structure wavelet decomposition signal, the range of nature earthquake is from 1 to 2 and the frequency is from 6.25 to 25 Hz respectively, but the range of explosion or collapse is from 4 to 5 and the frequence is from 0.7 to 3.1 Hz.

Abstract:A systematic dynamic characteristics of frozen soil under seismic loading is studied by means of dynamic triaxial tests. It involves dynamic constitutive model, dynamic elestic modulus in different temperatures of -2℃、-5℃、-7℃、-10℃. The model of dynamic parameters for the effect of low-temperature is established.

Abstract:By the research of geological conditions of geotherm in Lanzhou-Minhe basin, it is considered that the basin lies east section of Middle Qilian Upfold Belt and on the deep-stope belt of crustal thickness, where the deep and great faults with NWW and NNW direction become ascending channels for deep thermal source, and control the distribution of geotemperature.Combination of heat conducting faults and low conductive stratas easily form geothermal anomaly region. There are layered and banded thermal reservoirs in the basin. The conceptual model of geothermal reservoir in the basin is proposed in the paper, that is deep crust provides thermal resource; deep and great faults conduct geotherm;low heat conductive stratas accumulate geotherm and ground water runoff supply water.

Abstract:Using finite element method, the time-space evolution of stress field on North-south Seismic Belt and adjacent region is simulated,considering the geological structures and designing the model with viscosity characteristic. Through simulated calculation of evolution of stress field affected by 100, 010 years accumulated loading,it is found that the joint continuous effect from India-Australia plate, Philippine plate and Pacific plate determines the disturbance quantity of the stress state on the belt after the creep deformation has approached steady state. The phenomenon of seismic echo on North -south Seismic Belt is a synthetic reaction to the external loads (plate boundary force) after the regional stress field reaches a equilibrium state.

Abstract:The dating method according to gray of caliche-lamination is a new ideal for ideology of sediment. In this article, the train of thought and realization technique of this dating method are expatiated. First the caliche section is scanned directly with high resolution by flat scanner. After this, their gray values can be obtained and the gray-thickness graph is drown in computer by using our application program. Then the curve is compared with other dating results, such as the bathy-oxygen-isotope curve, loess-palaeosol sequence and loess-grain curve etc., therefore the age of caliche formation is determined. Meanwhile the correlation analysis on the different results is done, for several times scanning on the same profile, different positions on the same sample face, and different samples from the same terrace. The results show that the method is feasible.

Abstract:Caliche is the sediment which formed on surface of gravel in drought and semi-drought environment and reflecting environment and climate change. It contains mo re integral environment and climate information, can be used to analyze palaeo-climate and dating the forming age. In this paper, it is considered that the shades of caliche micro-lamination record the process of climate change through the discussion of sedimental mechanism of the caliche, and it can be compaired with other dating methods, such as bathy-oxygen-iso-tope curve, loess-palaeosol sequence, loess-grain curve, palaeo-magnetic curve and tectonic events etc., therefore its forming age can be determined.The age of the caliche represents the age of landform surface where the caliche locates on. By using this method the ages of the high-terraces in Heishanxia, Yellow River, are re-determined.

Abstract:The evolution features of cross-fault deformation in different scares during seismogenic process near epicenter of Menyuan earthquake (M_S 6.4, August 26, 1986)is analyzed. Based on theory of Discontinues Deformation Analysis (DDA)the Displacement Loading Method is applied to simulate vertical displacement velocity change due to focal rupture. The result shows that combination of vertical and lateral force produce the deformation change on earth surface, and the former may be more important.

Abstract:The seismic quiescent phenomena in Xinjiang is analyzed systemically. The result shows that the main feature of seismicity before medium-strong earthquakes in Xinjiang is seismic quiescence, and the forecast indexes of seismic quiescence are extracted through statistic method.

Abstract:Through systematic analysis on the relationship between the variation of precursor anomalies of underground fluid and moderate strong earthquakes, it is indicated that there are two kinds of short-term precursor anomaly of earthquake, which are turn style and single style, in Northern China. Based on the earthqauke cases, the characteristics of two kinds of precursor anomaly are discussed. It is considered that the approximately synchronous variation for two kinds of anomaly group in the reg ion should be given special attention to.

Abstract:Based on study of some precursors before 3 moderate strong earthquakes in south-east part of Gansu provice, it is found that all kinds of precursors show harmonious character in temporal-spatial. The result shows that the anomalies last shorter time and mainly in middle-short term, but in impending term is not clear. From one year to short-impending stage, the anomalies migrate to earthquake epicenter. The distribution of precursor anomalies and low b value are concentrated to same area. The relationship between the harmonious character of precursors and transportation of underground fluid and thermal material in deep crustal is discussed.

Abstract:In the paper, taking an engineering site of thermal power plant which lacats in northearn segment of Chinese North-south Seismic Belt as the ex ample, the deep geological tectonics, especially the exist of hid-den faults are studied by using the magnetic field anomaly date from the aerical magnetic survey. The application of aerial magnetic survey data in study of regional tectonics stability of engineering site is discussed.

Abstract:From Jan. 21, 1997 to Aug. 27, 1998, the strong earthquake swarm including 9 events of M_S 6 occurred in Jiashi, Xinjiang Uygur Autonomous Region. The focal mechanism solutions show that 9 events have both two nodes of NE and NW. In some people's opinions, the main rupture strike of the swarm is NNW direction. In this paper, through analysis on the precise location of aftershock sequences recorded by digital seismic array, focal rupture process and slipping directions, spatial distribution image of earthquake swarm, long-axis strikes of intensity isoseismal line, and dynamic change trends of micro-macro epicenters, the conclusion that main rupture strike is most likely NE direction is Obtained.

Abstract:According to the practice plan on mobile observation system of earthquake precursor for engineering of the anti-seismic and disaster-reduction demonstration area in the capital area, the sites of Beijing geomagnetic survey network were rebuilt and optimized during 2000~2001. The new network has obtained accurate and reliable data in the Beijing area during 2001~2002 by using G-856 magnetometers. Based on the data, the geomagnetic changes in the Beijing area were analyzed, the seismomagnetic precursor information was researched. The work has some practice effect to earthquake monitoring and prediction. At the end some suggestions for important work points in future are put forward.

Abstract:In order to adapt to the observational condition of magnetic declination and inclination with the high resolution and precision magnetograph, the azimuths among 7 measurement platform sand 4 azimuth marks in reconstructed Jinghai station, Seismological Bereau of Tianjing, are precisely measured by using classical astro-geodetic method, and 38 parameters with average error ±1.2″ are gained. After the measurements, 7 sets of instrument can be used at same time in all-weather.

Abstract:The anomaly features in electromagnetic wave data of Tianzhu station before five M_S >4. 0 earthquakes are analyzed. The result shows that the trend anomaly appears from on to 20 days before medium-strong earthquake, and its expression is, daily value rising suddenly from one-digit number to four-digit number.