1987, 9(2):1-5.
Abstract:This paper use the multiple selection and the external sensitivity of bifurcation in the dissipative theory to discuss some problems of earthquake prediction.
For the combinated faults, multiple selection is caused by the stohastivity of the beginning point of fracture. Besides, sometimes the earthquake process possibly become into chaostic. It means, there are some difficults for earthquake prediction. In order to comparatively definite predict earthquakes, we must study the interaction between the external factors and the earthquake source system.
1987, 9(2):6-15.
Abstract:This paper discusses the effect of the few basic rocks and ultrabasic rocks in the crust during the source process of earthquake by the physico-chemistry. Based on the preliminary studying as compared with practice, we analyse the viscosity of various rock types, discuss the relationship between origin of earthquake and rock viscosity with the activity of earthquakes, make a mark on the earth's surface which is determining stick slip or stable sliding of fault.
1987, 9(2):16-25.
Abstract:On the basis of the mechanical interaction between elastic deformation and fluid diffusion in porous materials, this paper takes the coupled constitutive equestions as mathematical model and solves to it. The patterns and changes of additional fault strength due to mantle uplift for three types of fault have been studied. In theoretical analysis, the mechical effects to fault strength produced by the changes of pore pressure from the fluid diffusion have been taken into full account. Primary results sh ow:(1)In space, the zones of strength weakening are located in the lateral of the uplift. (2)In time, triggered time behind the process of mantle uplift.
Besides, this also holds that mantle uplift may be a significant cause of the 1976 Tangshan earthquake development and occurrence through analysis. And strength weakening values have been also estimated.
Finally, the patterns of maximum principal shear stress due to the uplift have been obtained. The results show that the locations of rupture occur in the sides of uplift in crust and they are likely with high dip.
Zhang Bi'ao , He Genqiao , Liao Yuanmo , Chang Qiujun , Wan Fuling , Guo Yuying
1987, 9(2):26-32.
Abstract:This paper deals with the distribution of trace gases, such as H2, Hg, Rn, CO2 on the faults by means of analysis of the gases in the faults of the northeastern part of Arerjin Fault starting from Annanba Dam in the west and ending in the road of Changma in the east. The research pointed out that on the same profile, the concentration of the four kinds of gases not only have the syneronous change but also have some to do with the activity strength of the faults. In addition, the analysis shows that the concentration of the gases(H2, Hg, Rn, CO2) is trending to be higher in the west but lower in the east, which is accorded with the strong activity in the west and weak in the east for the faults.
This paper also discusses how to judge the dynamic state and how to predict the short-term and impending earthquakes by means of gas fixing point and gas periodical observation, pointing out that it is a practical method to make use of gas to study the activities of faults.
1987, 9(2):33-39.
Abstract:From the point of view of dynamic state, "rhythm" and "golden cut value" (that is, optimal selected value) are used to describe the migration characteristics of the strong seismic activities of the latest epoch in North China. The result is called "Dynamic rhythm" and the elliptical pattern visually shows the largest permissive rhythm range in space. In this paper, it has been considered that such "Dynamic rhythm" is the concrete expression of characteristics of neotectonic movement. It may make some contribution to estimation of earthquake tendency to study the "Dynamic rhythm" of seismic activity in every seismic zones.
1987, 9(2):40-45.
Abstract:In recent years some research results about earthquake prediction by means of seismological methods show that we can achieve some successes of predicting strong earthquakes by use of preparation gaps. First, we can draw primary gaps on the epicenter distribution pictures on small earthquakes. Then we find out the preparation gaps based on some criteria and evaluate the magnitude, time and location of future earthquake from emperical formulars. But we will meet the problem of false prediction of earthquake. In this paper we study the false prediction of earthquake by applying preparation gap. It is found that unload earthquakes occurred in the neighborhood of a preparation process of earthquake. So that no following earthquake will occur within the preparation gap. we sum up some characteristics of unload earthquakes and evaluate the effects to reduce false palse prediction of earthquakes from them. It is possible that the unloading role may be used to explain the phenomena of other precursors of no following earthquake.
1987, 9(2):46-51.
Abstract:Anomalous change of some meteorological factors had taken place before the great earthquake of Ms=7.4 Occurred in Wuqia at 20 o'clock on August 23, 1985. Doing a statistical calculation of the meteorological data accumnlated over the years in Wugia and the neighbonring zones and comparing the obtained results, We discovered that the anomalies of the rainfall, and temperature, atmospheric pressure and temperature which had occurred before the earthquake in the central zone of earthquake were very apparent, and the earthquake epicentre is corresponding to the anomalous centre. This declares that some internal relations between meteorological phenomenons and earthquake exist really, so we think that the moterological factors can play a part in the earthquake forecast with a method of combining the meteorolocal factors with other measures.
1987, 9(2):52-56.
Abstract:An earthquake (5.3) occurred on November 23, 1984 in Lingwu county, Ningxia Hui Autonomous region (38°04, N, 106°13, E, H=14km, I=Ⅶ). It is the strongest shock in Yinchuan plain since 1962. In this paper, it was reported that the process of medium and short-term forecast of this earthquake and its major precursory science basis. The results demonstrate that it is entirely possible to do medium and short-term forecast before a moderate earthquake using the anomalous characteristics of Seismic pattern and other precursory anomaly phenomena under favorable condition, but it is fairly difficult to do imminent-term forecast just prior to a moderate earthquake at present.
Jia Huazhou , Dong Shouyu , Wan Dikun
1987, 9(2):57-62.
Abstract:This paper systematically discusses the whole process for nearly five years in which the tendency descension of water level of Wanquan well changed into tendency ascension. It has been considered that it is not seismic precursory information, but a reaction of unprecusoray strain information. The water level descension lasted for two years is as a result of decrease of pore water pressure caused by the consumption of elastic reserve under the special hydrogeological and observation conditions; the water level reversion for more than half a year is as a result of that water-filled fault changed the performance of water conduction, thus caused the changes of water quantity and water head; the developing process for nearly two years in which the accelerative ascension of the water level turns stable with high value is a result of further changing the conduction performance of water-filled fault for the sensitive Wanquan well under the reaction of effects of Heze earthquake and some large distant earthquakes.
1987, 9(2):63-69.
Abstract:This paper evaluates 26 radon wells in Gansu province including their type of construction, the environment of their outcrop, the technique for observation, the instruments and equipments, the quality of data and the capacity of reflecting earthquakes, especially after the analysis of five moderate and strong earthquakes, proving the existence of radon message for earthquakes and the capacity of monitoring earthquakes by radon observation net, And then this paper also analyses the major reason why earthquakes can not be predicted effectively at present.
1987, 9(2):70-74.
Abstract:A violent earthquake of 7.5 magnitude occurred in Xinjiang Balikun county on June 11, 1842. It created visible surface deformation and seismic fracture zone about 23 kilometers and 2 m. of vertical displacement. The intensity of seismic center was ten degrees.
This article is written according to the investigation in 1985 and the history records. Writers of this paper have represented the contours of seismic intensities, counting seismic magnitude, placement of the seismic center, depth of the seismic focus, seismic moment and stress drop and researching characteristics of the seismogenetic tectonics.
1987, 9(2):75-80.
Abstract:In the paper, the macroscopic parameters, intensity and geological tectonic conditions of the Menyuan earthquake of 6.4 which occurred on Aug. 26, 1986 are briefly introduced. Moreover, it remarkably depicts the precursory phenomena of the quake. The seismic trend in the, epicentral and adjacent areas is preliminarily predicted.
1987, 9(2):81-87.
Abstract:Based on correlation of horizontal dislocation with the length of betrunked gulch, it is proposed that the active Ertai Fault had ruptured 5 times since Holocene. The earthquake of M=8 took place during every stick-slip fracturing. Paleoseismic recurrence period was approximately 1800 yrs. We have estimated that the Ertai Fault will rupture again in the 3700 A. D. The earthquake will occur on the southern end of the active fault. This estimation is suppored by severed evidences, such as the surface of multi-seismic fault, multible cliff of displacement, seismic colluvial deposits and excavation.
Wang Jin , Liu Jiangfeng , Tianjun
1987, 9(2):88-88,110.
Abstract:根据甘肃省地震台网测定,1987年元月8日02点19分在甘肃省迭部境内发生了一次5.9级(M_s)地震。震中位于北纬34°10',东经103°14'。震源深度为11公里。地震发生后,我们收集了甘肃、四川、青海等省地震台网和全国各基准台站所记录到的P波初动符号共72个。
Yah Zhide , Zhang Cheng , Xiao Lizhu
1987, 9(2):89-93.
Abstract:1986年8月26日青海省门源6.4级地震,是祁连山地震带自1954年山丹7(1/4)级地震之后,迄今所发生的一次最强烈的地震,从而引起了人们的关注。本文着重研究门源地震的序列特征,並对本次地震后的趋势及地震大形势进行了分析和研究。
1987, 9(2):94-96.
Abstract:在1974年溧阳5.5级地震和1979年溧阳6.0级地震之后,作者对华北北部的中期地震趋势进行了研究,发现溧阳两次地震与华北北部地震有呼应关系,现将研究结果介绍如下。
1987, 9(2):97-100.
Abstract:黄羊川断裂西起天祝县冷龙岭东北缘,经关家台,穿曹家湖水库,沿黄羊川河的北侧断续延至米家山和营家山的北坡,总体走向北东东,长200余公里,其东端有可能与中卫-同心断裂带相接。
Lin Huaicun , Jiang Haikun , Wang Baoping , Gu Zhenqing
1987, 9(2):101-105.
Abstract:关于震级与烈度的定量关系已有不少研究成果[1-8]。但是上述文献中的公式都是利用强烈度(6-11度)区统计出来的。我们利用发生在华北地区及其邻区的历史及现代的地震资料,统计出了烈度为4-7度区的面积与震级的关系式。
1987, 9(2):106-109.
Abstract:近年来,我国的一些地震工作者开展了对"诱发前震"的研究,取得了一定的经验。在地震学方法清理攻关中,对"诱发前震"的预报效果予以肯定。我们利用新疆南北天山地震带中所发生的地震对这种方法进行了检验,进一步证实了地震带中诱发作用的存在,有些大的远震(相对远)可以诱发外区大震的较小前震。
Sopyright:China Earthquake Engineering Journal