1984, 6(1):1-3.
Abstract:从1954年2月11日山丹地震(Ms=7(1)/(4))发生到现在已三十年了。这是我国解放后发生在有一定人口密度地区的第一个地震。当时有一定伤亡。这个地震发生时正是我国第一个五年计划开始时期。为了对我国各大建设工程地区提供抗震烈度,中国科学院地球物理所李善邦先生、付承义先生和谢毓寿先生以及当时的赵九章所长都积极领导和组织地震工作者完成上述任务。
1984, 6(1):4-10.
Abstract:Theoretical studying(1) has indicated that the behaviour of surrounding medium of water has a large effect on the stress corrosion process of fracture in rock. So far, experiments made for stress corrosion in rock have been done under the situation of static water. In this experiment, the subcritical develop characteristics of fracture caused by stress corrosion n Yuennan marble samples under the situation of static and flowing distilled water have been studied respectively. The results show that flowing of the medium of water around fracture may accelerate the stress corrosion process of the end of fracture. It is perhaps of great significanse to the study of earthquake source process and the precursor just before earthquake.
The Compact Tensile (CT) samples have been used and the stress intensity of Yuennan marble has been measured. The fracture toughness of Yuennan marble was found to be KIC=(1.41±0.03)kg·mm-3/2. The results of man-made narrow cut samples and natural initial fracture samples have been compared. It is therefore supposed that the natural initial fracture sample may be substituted by man-made narrow cut sample for the fracture toughness measurement of Yuennan marble CT samples.
Lu Guang-ting , Zhao Guang-kun , Xie Yuan-ding , Jin Ming , Jiang Xu-yuan
1984, 6(1):11-16.
Abstract:The electric resistivity of Lanzhou Heko layer water saturated sandstone was investigated experimentally under uniaxial load at room temperature and the changes of electrical resistivity was observed at the angles of 0°, 90°, and 45° to loading direction.
Primary experimental results are as follows:(1) when loading direction is vertical to the layer, the changes of electrical resistivity ρ" (parallel to loading direction) and ρ⊥ (vertical to loading direction)are divided into three stages:increase-stabilization-decrease; (2) when the loading direction is parallel to the layer, the changes of electrical resistivity ρ" and ρ⊥ are characterized by obvious anisotropism. For the abovementirned loading directions, the change of electrical resistivity at an angle of 45° to layer surface whether parallel or perpendicular, is smaller. Then these results are explained qualitatively. Owing to the fact that the amplifier factor of the sandstone is smaller (10-102), it is not suitable to build the geoelectric station on the sandstone.
1984, 6(1):17-24.
Abstract:In this paper the auther analyses four great earthquakes data (Daguan 1974, Bohai 1969, Songpan 1976 and Tangshan 1976, 7≤Ms≤8) and realizes that the long peroid creep phenomenon prior to the Songpan earthquake has not been isolate, it also exists for the Bohai and Tangshan earthquakes. Its aspects resemble one another in period (T:20-80s), in amplitde (A:10°-102μm), in energy(Ms:4-5 grade) and in wave propagation. But the creep Wave velocities were different; 1.1-1.2KM/s, 2-3KM/sand 3.5KM/s to Songpan, Bohai), the Tangshan earthquakes, respectively.
The frequency spectra changed with △, the disperse of the creep were different prior to the Songpan and Tangshan earthquakes. The creep sources were not the same as the epicenters, but near it. The time ahead of the earthquake occurrence was generally 1-2 days. It is interesting that there was no long period creep prior to the Daguan earthquake(Ms=7.1), but the special pulse of the earth(10-20s).
In this paper some kinetic analyses have been made only. Its results are the same as from C. H. Scholz, Guo Zeng-jian, J. D. Byerlee and J. H. Dieterich et al., but different from Chen. It may be useful to theory and practice of short and temporary predict on the earthquake.
Zhang Yao-guo , Wang Zong-lian
1984, 6(1):25-31.
Abstract:In this paper, using the observational data of seismological stations of Sichuan province, the Variations of some seismometry indications before the occurrences of moderate earthquake have been discussed.
Principal aspects are shown:(1)Variations of assumed stress strop; (2)Variations of β=ML/lgτ; and(3)Variations of θ=Ks-Kp.A simple method for measuring the seismic moment is also proposed here and the seismic moments of some earthquakes have been measured. Finally, we hare discussed the possibility of the predication of an earthquake by using the ratio for the envelope of seismic waves.
1984, 6(1):32-37.
Abstract:During the Haiyuan earthquake(Ms=5.5) the tilt step was observed by six tilt stations in the 260km range around the epicentre. The tilt step isogram was a rather regular ellipse. The direction of long axis of the ellipse was NW-SE. Decrease law of the tilt step value was clear. The value was the greatest near the epicentre. The high value area was a stripe-belt shape that was distributed in the direction of NW-SE and was in agreeing with the long axis of the innermost isoseismal line, the strike of geologic structure lines and the result of the mechanism of the earthquake foci. Therefore, the tilt step is the reflection of fault activities in the earthquake. The high value area can be regarded as a basis for our inference of earthquake fault.
Zhao Hong-sheng , Huang Yun-bao , Cao Fu-lian
1984, 6(1):38-42.
Abstract:In this paper the more-than-twenty-years records of the atmospheric rainfall around Kunming are compared with the seismic data. It pointed out that there is the statistical relationship between the changes of drought-inundation and the earthquakes activities. The effect of inundation is especially marked one year before the earthquakes. Based upon this, we suggest an experiential method of predicting moderate-strong earthquakes in the region.
1984, 6(1):43-48.
Abstract:Before the Heishui earthquake (Ms=5.4) of July 13,1978,in Sichuan province, some short term and imminent anomaly characteristics of the ground tilt were recorded by five tiltmeters in Wenjiang area. About ten days before the earthquake the tilt monodirectional components daily daerage values curve showed a big change and a acceleration of tilt. Before the earthquake the tilt vectors tied. The long axes of the ties almost pointed to the epicentre. The directions coming out of ties pointed to the place where the earthquake took place or back from the future earthquake. For some days before the earthquake the deviations of tilt directions appeared. These anomalies can be regarded as one of the bases of predicting earthquake.
1984, 6(1):49-57.
Abstract:The "Fisher" method is a mathematical method which divides the sequence sample into most excellent segments. The method is characterized by objectivity and optimum. In this paper the author applies the method to divide the earthquake activity periods. Concrete divided examples are given. Finally some questions related to applying the method are discussed.
1984, 6(1):58-64.
Abstract:The variation of soil radon resulting from explosion earthquake, using 160 tons of TNT, in the loess stratum in Yongdeng county, Gansu province, in July 1982, is presented in this paper. This study involves the geological conditions of the experiment field used for the explosion in the loess area, the plan associated with the site distribution for the soil radon measurement, and its two observational methods as well. The results show that the effects of earthquake explosion in the loess area on the variation of soil radon are apparent. It is indicated in this study that there are five features with respect to the variations of radon, i. e. (1) generality of its occurrences; (2) similarity in regard to the variation patterns; (3) its differences with space; (4) its sudden changes with time; (5) attenuation of its amplitude with the distance from explosion site. The other characteristics of its variation and the mechanisms concerned are also analyzed and discussed primarily.
1984, 6(1):65-71.
Abstract:Based upon the analysis of regional geotectonic background of the Tianshui area, in this paper it is emphatically pointed out that Lojiapo earthquake of magnitude 7(1)/(2) in 1654 occurred at the most deep depression of Tian-Li basin since Kainozoic Era, where the conjunction portion was formed as a result of the interaction of the structure in NE trend with active structure in NNW trend. The tectonic conditions of the occurrence of Tianshuizhen earthquake (Ms=6) in 1936 and the causes of the formation of Tian-Li basin are also discussed.
1984, 6(1):72-76.
Abstract:Based on the sixteen gravity sections chosen, the author has calculated anomalous value of gravity in the depths of the earth. Basic form and degree of hidden depth in the earth of the Moho discontinuity have been got. The thickness of the crust in Ningxia area is 1-5KM greater than that of Shanxi area and 6 KM less than that of Gansu area. There are three segs and one upheaval of the Moho discontinuity in this area. They are the Yinchuan-Pengluo seg, the Wuzhong-Majiatan seg, Haiyuan-Lijunpo seg and the Zhongning-Zhongwei upheaval. On the south of Ningxia area they are generally bounded by the Daluoshan Mountain, the Xiaoluoshan Mountain, Yuwang and Jingyuan. Curst is getting thiner and thiner on the east of the bound and thicker and thicker on the west of the bound. Historical strong earthquakes just occurred on the stair belt between the segs and the upheaval of Moho dicontinuity in Ningxia area.
1984, 6(1):77-83.
Abstract:For the last 10 years Chinese seismologists have been studying the seismic velocity ratio anomalies before and after a series of strong and moderate earthquakes (Feng, D. et al., 1974; Feng, D., 1975; Feng, D. et al., 1978) Since many seismologists hold different viewpoints on using premonitory seismic velocity variations as earthquake precursors,we must continuously make detailed studies of the different characteristics of the seismic velocity anomalies in different region.
In this paper, we collected data for the VP/VS anomalies before and after some earthquakes occurred in Province Gansu and its vicinity with magnitude about 4 and >4 during the period 1970-1983.
We have investigated and discussed some general temporal and spatial characteristics of VP/VS anomalies; namely, the time-dependent characteristics of VP/VS variations, and the spatial characteristics of regions concerning the future strong or moderate earthquakes.
1984, 6(1):84-92.
Abstract:In the DD model of earthquake,it is supposed that the water come from outside of focal region. It was indicated that the high conductivity layer in middle earth's crust, which often appears in the earthquake belt and becomes the bottom of the focal region of some large earthquakes, may supply rich water for fluid diffusion[1]. But is there some interior source of water in the focal region? We take the deep physical circumstance of the focal region of the Changma earthquake in 1932,as an example to illustrate that it is possible for some earthquakes.
1984, 6(1):93-94.
Abstract:1982年6月28日至30日,陕西关中周至县南面发生了一次小震群活动,共发生小震和微震77次,释放的地震波总能量为1.11×1013尔格,相当于一个ML=3.5级地震。
1984, 6(1):95-96.
Abstract:本文使用兰州地磁台1959年至1981年的资料,分析地磁场长期变化特征。图1为兰州台的地磁变化(年均值)图。
1984, 6(1):97-99.
Abstract:1978年以来,利用陆地卫星多光谱扫描像片,对天水-礼县地区的构造特征进行了目视解译,对本区的卫星影像显示的构造特征有一个初步认识。1981年又将本区的卫片做了假彩色密度分割和图像的计算机数字化剖面量测。补充和修改了目视解译中的不妥之处。本文对区内北东向线性构造的展布特征及其地震地质意义做了初步探讨。
1984, 6(1):100-102.
Abstract:昌马地震形变带受到地震地质界广泛的重视,己有多篇文章作了介绍[1][2][8]。笔者近来对该带东段西水峡沟至红窑子长约40公里地带作了航片判读与简短考察*,发现了其间北东东(照片1、3)与北北西向地震形变带与活断层的水平断距**。
Xiang Guang-Zhong , Lu De-hui , Li Su-qin , Wang Duo-jie , Dong Zhi-ping , Gao Bo , Lin Tong , Chen Yu-hua , Dang Guang-ming
1984, 6(1):103-105.
Abstract:1983年7月27日青海省祁连县境内发生了一次有感地震,为了验证我们前两年工作中所做的结论,组织了现场考察,并对原仪器震中进行了修订。
Sopyright:China Earthquake Engineering Journal