Table of Content

09 March 1988, Volume 10 Issue 1

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Brief Report

A STUDY OF THE RECENT TECTONIC ACTIVITY IN JIANGSUSHANDONG-ANHUI AREA

Wang Ruo-bai

1988, 10(1):  1-14. 

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In this paper two vertical deform anon maps have been drawn, based on the accurate leveling data of 1950-1980, in Jiangsu-Shandong-Anhui area. Along combining with neotectonic, geological basis and crustal deformation data, an analysis of the recent tectonic activity in the studied area has been made,and some conclusions have been drawn as follows: (1) The Tancheng-Lujiang fault zone across the studied area is the keY tectonic ele m ent in recent tectonic activity, and the crustal deform ation is controlled by the fault zone. (2) A study of the two deformation maps shows that the section of the Tancheng-Lujiang fault zone in this area is a creeping section, but both ends of the section are locked parts. The stress concentration ought to be accumulated in these parts. (3) Difference between the two maps suggests that the activity character of the fault zone is right lateral slip during 1950 to 1970, but reverse activity has occurred since 1982 to 1983. This suggests that the most intense earthquake in East China (magnitude was estim ated to be 8.5 and occurred in 1668, south Shandong) could be generated with the tectonic activity of the Tancheng-Lujiang fault zone.

SEISMOTECTONIC BACKGROUND AND RECURRENCE INTERVAL OF GREAT EARTHQUAKES IN 1679 SANHE- PINGGU M = 8 EARTHQUAKE AREA

Xiang Hong-fa, Fang Zhong-jing, Xu Jie, Li Ru-cheng Jia San-fa, Hao Shu-jian, Wang Jing-bo, Zhang Wan-xia

1988, 10(1):  15-37. 

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Basined on comprehensive prospecting and investigation, the authors have ascertained that the 1679 San-he-Pinggu M = 8 earthquake occurred in the intersection region of active faults having deep-seated structural background. The NE-trending New Xiadian Fault, which was characterized by dextrall tensile-shear dislocation, was the seismogenic fault of the 1679 M = 8 earthquake. It is suggested that the macroscopic epicenter of the earthquake should be located in Pangezhuang area, where the vertical displacement of seismic faul’ was up to 3.16m. According to the average seismic slip rate in this area, and the displacement value of earthequake with a certain magnitude, the recurrence interval of M = 7.5, M=7.0 and M = 8.5 earthquakes in the magistoseismic area of 1679 M = 8 earthquake on Xiadian Fault Zone have been estimated to be 3800,1750, and 800 years (the lower limit), respectively.

A NEW SURFACE RUPTURE ZONE OF EARTHQUAKE NEAR THE DAMXUNG, TIBET

Wu Zhang-ming, Cao Zhong-quan, Deng Qi-dong

1988, 10(1):  38-38. 

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DEPOSITIONAL ENVIRONMENTS OF GRAVELS, TERRACES DISPLACED BY WAIRARAPA FAULT AT WAINGAWA RIVER AND RECURRENCE INTERVAL OF 1855 EARTHQUAKE, SOUTHERN NORTH ISLAND, NEW ZEALAND

Cheng Shao-ping

1988, 10(1):  39-50. 

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The heigher and older terraces at Waingawa river, southern North Island, were formed by the alternate effect of aggradation and erosion under periglacial climate during -late-Pleistocene and the lower and more recent ones by present-day climate since mid-Holocene. These terraces have been displacad 279m, 100m, 57m and 28m respectively. The estimated average slip rate of the Wairarapa fault since 10000 B. P. is 10mm/y. The recurrence time for magnitude 8 earthquakes like that which occurred in 1855 is estimated to be 1500 years.

PRELIMINARY APPROACH TO THE MID-RANGE FORECAST OF MODERATE EARTHQUAKE IN THE JIANGSU PROVINCE AND SOUTHERN-YELLOW SEA

Hu Lian-ying, Li Zhuo-hua

1988, 10(1):  51-60. 

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On the basis of main characteristics of moderate earthquakes: periodicity, cruster, repartition, and migration regularity and simularity between the forshock activity paatern of moderate earthquake: seismic gaps, seismic bands, and seismically quiet area in a time-space diagram and precursor emerged in small earthquake in future, the author made a preliminary approach on the tendency of moderate earthquake for next some years in Jiangsu Province and Southern-yellow sea area.

ESTIMATION OF HYPOCENTRAL PARAMETERS FROM GEOMETRY OF SEISMIC INTENSITY DISTRIBUTION

Wang Sheng-zu

1988, 10(1):  61-69. 

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The relationship between geometrical factors of seismic intensity distribution and hypocentral parameters of strike-slip earthquake is considered by means of a simplified elliptic model of hypocentre in which the effects of environmental stiffness of hypocentral region and nonuniform resistance along fault zone are taken into account, and a new method, so-called isoseisms method, is developed preliminarily for estimating stress drop and slip displacement of historical earthquake. Also, the relationship between axes ratio of hypocentral ellipse and orientation of maximum principal stress relative to fault zone is presented in this paper. The method has been examined by estimating the hypocentral parameters of Tangshan(1976), Tonghai (1970), Luhuo(1973) and Yongshan (1974) earthquakes and comparing them with those estimated by the traditional methods.

NUMERICAL MODELLING OF FORMATION MECHANISM OF SHANXI EN-ECHELON GRABEN

Loo Huan-yen, Kong Xiang-hong, Gao Wei-an

1988, 10(1):  71-77. 

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To illustrate quantitatively the formation mechanism of the rightstep faults, an ela-sto-visco-plastical three-dimensional model with a discontinuous pre-existing buried fault is presented and solved numerically by a general total initial strain procedure. Body force and localized upward force at the model base as well as a rightlateral couple acting beneath the upper crust are required to develop horizontal tensional stress above the buried fault with a direction perpendicular to the long axis of these basins.

THE EARTH TIDE AND SEISMIC WAVE EFFECTS ON WATER LEVEL IN THE TANGKENG WELL GROUP, FUJIAN PROVINCE

Che Yong-tai, Zhu Qing-zhong, Yu Jin-zhi, Huang Peng-fei

1988, 10(1):  79-86. 

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There are seven wells in the Tangkeng, Nanjing county, Fujian province, and their distance each other is smaller than some hundred meters. The earth tide and seismic wave are shown in their character are various each other. The characters and the relation between these wells and their geological and hydrogeological conditions are discussed in this paper.

MATERIAL COMPOSITION OF THE FAULTED AND FRACTURED ZONE AND DETERMINATION OF THE AGE OF FAULTING IN THE PUBUGOU AREA, SICHUAN PROVINCE

Feng Jin-jiang, Hu Bi-ru, Niu Luan-fang, Zhang Bing-liang

1988, 10(1):  87-92. 

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In this paper, characteristics of neogenic clay minerals and micro-surface texture of quartz fragment in fault gouge are discussed. Clay minerals are analysed mainly by X-ray diffraction, whereas miero-surface texture of quartz fragments is studied by SEM. The relative age of faulting is determined with the analysis of corroded surface texture of quartz fragments.

RADIOCARBON DATES(5)

Jiao Wen-qiang, Peng Gui, Zhang Jing-wen, Chen Yi-jian, Li Gui-Ying, Li Hong-chun, Zhang Jia-Lin

1988, 10(1):  93-96. 

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