WAN Yong-ge , SHEN Zheng-kang , GAN Wei-jun , QI Fu-rong
2003, 25(1):1-7.
Abstract:From 1937 5 MS ≥ 7.0 earthquakes occured along Eastern Kunlun active Fault Zone:MS 7.5 Huashixia earthquake in 1937, MS 7. 1 Dulan earthquake in 1963, MS 7. 3 Mani earthquake in 1973, MW 7.5 Mani earthquake in 1997 and MW 7.8 west to Kunlun Mountain Pass earthquake in 2001. The stress transfer and fault activation among large earthquakes in the fault zone, in northern of Tibet plateau, are studied. The Coulomb stress change on the fault plane of subsequent earthquakes produced by seismic dislocation in elastic half space are calculated. The result shows that Coulomb failure stress on the fault plane is increased by the previous earthquake in every events, it is in favor of occurrence of subsequent events, and the calculation indicates that after west to Kunlun Mountain Pass earthquake (MW 7.8), the Coulomb failure stress in Xidatan -Dongdatan fault segment is significantly increased up to 0. 006~0. 02 MPa, that imply the probability of seismic hazard in this region increased.
GUO Zeng-jian , HAN Yan-ben , WU Jin-bing
2003, 25(1):8-11.
Abstract:The great west to Kunlun Mountain Pass MS 8.1 earthquake in 2001 occurred in peak term year of solar activity. The magnetic storms can induce eddy current heating on the fault plane of EW or near EW strike seismogenic faults, and trigger off earthquakes in the peak term years of solar activity. Based on statistics, among the MS ≥ 8.0 great earthquakes in China and Mongolia, most events which occured on the fault with strike of EW or near EW are in the peak term of solar activity; but for others which occurred on the fault with strike of NS or near NS are predoninately in the valley term of solar activity. The similar result is also obtained for MS ≥ 7.5 earthquakes.
KANG Chun-li , CHEN Zheng-wei , CHEN Li-ze , TIAN Qin-jian , LIU De-fu
2003, 25(1):12-15.
Abstract:Based on the two products of infrared from satellite remote sensing, i.e.. Outgoing Longwave Radiation (OLR)and Bright Temperature(BT), the precursor anomaly feature of infrared radiation before west to Kunlun Mountain Pass M 8.1 earthquake on Nov. 14, 2001, is analyzed. The result shows that the increasing anomaly of OLR appeared since a month and BT since a week before the earthquake, and both anomalies stretched along the seismo-tec-tonic zone in the epicenter district.
DING Jian-hai , YU Su-rong , XIAO Wu-jun
2003, 25(1):16-21.
Abstract:On the base of recorded data in many years from the network of geomagnetic observation in China, the anomalous feature of appearance time for minimum of diurnal variations (low-point time)of the geomagnetic vertical component and the variation of their spatial distribution (phenomena of low-point displacement)are studied. Such phenomena of geomagnetic anomalies is well-correlated with strong earthquakes. It is found that most earthquakes occur near the boundary line of sudden changed low-point displacement and generally within four days before or after the 27th and 41th day counting from the day of anomaly appearance. The low-point displacement also appearanced on Oct. 10, before west to Kunlun Mountain Pass MS 8.1 earthquake on Nov. 14, 2001. The possible "induced magnetic effect trigger" mechanism of the low-point displacement is studied.
WANG Lin-ying , CHEN Pei-yan , LIN Bi-cang , DING Qiu-qin
2003, 25(1):22-27.
Abstract:Before west to Kunlun Mountain Pass MS 8.1 earthquake, the anomaly coupling phenomena of seismicity quiescence in large area, high b value, high modulation and low entropy value appeared obviously. The anomolies of seismicity in different time-space scales before great earthquake are analysed and the prediction possibility to great earthquake is discussed.
2003, 25(1):28-34.
Abstract:The pregnant process of west to Kunlun Mountain Pass earthquake with M 8.1 in 2001 is researched in a hundred years and 45°×35°space, and the seismicity image evolution of moderate strong earthquakes is scaned in time and space. It is considered that in long, middle, short, and impending terms the different pregnant stages of the M 8.1 earthquake are clear, the systematic seismicity images for every stage are given, and the symbolical earthquakes are found for each stage. Finally, the particularity of great earthquake with M 8.1 and difficulty of earthquake prediction are showed.
2003, 25(1):35-39.
Abstract:According to time sequence, the pregnancy and evolution process of west to Kunlun Mountain Pass M 8.1 earthquake in 2001 is divided into 5 stages, based on linking up the data from the transition of geophysical fields, the evolution of seismicity patterns of moderate strong earthquakes and the change of dynamic environment around mainland of China before the event; the simultaneous change of some observatory terms; the seismicity correspondence, the adjustion of precursor field and the continual quiescence of earthquake (MS ≥ 5)after the event.
WANG Zheng-zheng , LIU Hong-gui , MEI Wei-ping , ZHANG Xi-hai
2003, 25(1):40-45.
Abstract:Great earthquakes M ≥ 8 in China are basically distributed in 5 seismic zones and bands:southern Qinghai Tibet Pleateau and Yunnan seismic arc zone, NE striking seismic band in northeastern Xinjiang area, 35° N line and South-North seismic band, Northern China strong seismic zone, and Taiwan seismic zone. Very often, the great earthquakes occur in pairs, or with predominant period. Different dynamical sources may exist for the great earthquakes in different seismic zones and bands. 3~10 years after the occurrence of an M ≥ 8 earthquake in Xinjiang area or Taiwan area, a dense seismic activity with magnitude 6. 5 may appear in north part of Northern China area, and 7~15 years after the event, Jianghuai seismic zone may enter a seismic active period with the magnitude 6 earthquake as the mark. The great M ≥ 8 earthquakes in Northern China have obvious seismicity reducting effect on the two sub-zones of Northern China zone.
LIU Dong-wang , SHEN Xiao-qi , LIU Ze-min , LU Cheng-min
2003, 25(1):46-51.
Abstract:The seismic tendency in mainland of China after west to Kunlun Mountain Pass MS 8.1 earthquake is analysed by the comparing of seismicity in different active period, the change of dynamical condition around mainland of China and the migratory rule of strong shock in western China. The effect of M ≥ 7.5 earthquakes in western China on seismicity in eastern China is statistically analysed too. The result shows that the fifth active period of seismicity since 1900 is going to end, but the seismic frequency and energy releasing are not enough, and the dynamical conditions on the border of China dosen't change after the M 8.1 earthquake, so it is possible to occur M ≥ 7.0 earthquake in mainland of China in future several years especially in northwestern area of western China. The effect of M 8.1 earthquake on seismicity in eastern China is about M 6.5
LIU Xiao-feng , YANG Li-ming , FAN Bing
2003, 25(1):52-58.
Abstract:The seismicity character in northern Qinghai-Xizang plateau after west to Kunlun Mountain Pass MS 8.1 earthquake in future 1~3 years is analysed by using date of some previous events. The result shows that the seismicity of moderate strong earthquake in the area is strengthened after M ≥ 7.0 earthquakes along Eastern Kunlun Fault and adjacent areas,The strong shocks in Qilian Mountain and Eastern Kunlun Seismic Belts are occurred alternately. The main active regions of moderate strong earthquake are some stress transition sites and extruding-tectonic areas on great strike-slip active faults, such as mid-eastern segment of Eastern Kunlun Seismic Belt,western end and mid-eastern segment of Qilian Mountain Seismic Belt.
2003, 25(1):59-63.
Abstract:Seismogenic process of west to Kunlun Mountain Pass MS 8.1 earthquake is consists of three evolutionary stages for seismicity pattern. The first stage is background gap formed by MS ≥ 6 earthquake from 1959; the second stage is pregnant gap formed by MS ≥ 5 earthquakes from in 1994, and the third stage,"imminent earthquake gap" lasts 4 months before the MS 8.1 earthquake. At the later period of the pregnant gap, seismic bands in 1~2 years appeared in Qinghai-Xizang block and western China. Along with the formation of the "imminent earthquake gap", no small earthquake occurred in the region. The time-space evolutionary feature of MS 8 earthquakes in western China is discussed at the end.
2003, 25(1):64-69.
Abstract:The precursor data of ground tilt, stress and geotemperature in deep well before west to Kunlun Mountain Pass MS 8.1 earthquake from some stations in Qinghai province are analysed, and some precursor features in long-range station are obtained and compared with the one in near-field station. The result is helpful to short-term prediction of strong earthquake.
GAO Yuan , PU Xiao-wu , CHEN Yan-ping , LI Ling-fei , HAN Ying , WANG Jin-yan
2003, 25(1):70-73.
Abstract:It is found that an uniform stress field is exists in west of China by analysising the data of borehole strain from Wudu,Gaotai stations in Gansu province and Panzhihua, Xichang stations in Sichuan province, and the stress field is consistent to the mechanical charactor of deformation belt of west to Kunlun Mountain Pass MS 8.1 earthquake on Nov. 14, 2001. All the strain data in 4 stations show the obvious short-term anomaly before the 8.1 earthquake.
LI Qing-lin , QIN Jian-zeng , ZHANG Xiao-pu
2003, 25(1):74-76.
Abstract:Significantly anomalous variation of gravity field in Northern China occurred before M 8.1 earthquake at west to Kunlun Mountain Pass. It may shows that obvious precursors(field-precursor) could take place in broad extent before a strong earthquake. In present time the anomalous variation of gravity field still exists in Northern China region, may imply the next M 7~8 earthquake in western China.
2003, 25(1):77-81.
Abstract:The subsidence and failure of loess hills induced by Yongdeng MS 5.8 earthquake in 1995 indicats that damage exists even in moderate strong earthquake in loess area. The 3-D Finite-Element method and computer-added analogue are used to study and analyze the mechanics of deformation on loess hill in Yongdeng earthquake.
WEI Huan , ZHANG Zhao-dong , GENG Jie , WANG Zhong-min , YU Li-ye
2003, 25(1):82-85.
Abstract:The theory and method of load/unload response ratio is led into the analysis for data of underground water level. Besed on the air presure effect to water level in confined well, taking the stochastic variety of air presure over the earth's surfase as load/unload force, the load/unload response ratio of water level to change of air presure in water well is proved theoratically to be feasible, and the method is given. Using the method the load/unload response ratios of water level in Lu-14, Lu-15 well, Shandong Prov., before Cangshan Ms 5.3 earthquake in 1995 are calculated, and the characteristics of the response ratio change is analysed.
FAN Xue-fang , ZHANG Shu-liang , WANG Ji-yi
2003, 25(1):86-88.
Abstract:The reliability of anomaly of water-radon in Dingxiang spring observation in 1996 is discussed, based on data of the hydrogeologic condition at the spring, the characteristics of water-radon anomaly and the normal influence fectors from environment. It is considered that the anomaly of water-radon not only correlates with air temperature and waterfall, but also with variation of stress-strain in rock, is the reliable precursor anomaly before Zhangbei M 6.2 earthquake in 1998.
YUAN Dao-yang , LIU Xiao-long , MA Er-man , XIAO Li-zhu , CHEN Wen-bin , GAO Xiao-ming
2003, 25(1):89-92.
Abstract:Based on the data of field investigation after Sunan MS 5.3 earthquake on July 11, 2001, the principal parameters, intensity, damage, seismogenic tectonics of the earthquake are summed up.
YANG Xue-xiang , SONG Dong-lin , CHEN Zhen
2003, 25(1):93-93.
Abstract:2002年上半年,伴随着厄尔尼诺现象的日益加剧,全球性重大自然灾害频繁发生.6月20日发生在中国黑龙江省鸡西煤矿的瓦斯爆炸事件和6月22日发生在伊朗的强烈地震,时间恰逢月亮近地潮的6月19日和太阳潮半日形变最大值的夏至的6月21日附近,是地球形变和排气较强烈的时段.
Sopyright:China Earthquake Engineering Journal