WANG?Shuang-xu , ZHANG?Xi , ZHU?Yi-qing , ZHANG?Xiao-iang , ZHANG?Si-xin , XUE?Fu-ping
2012, 34(2):105-113.
Abstract:Using the regional leveling, fault-crossing short survey since 1970s, and GPS, mobile gravitation observation data since 1990s in the north segment of the south-north seismic belt of China, combining with geologic structure and recent earthquakes ( Ms ≥ 6. 0) in this area, the basic characteristics of structure deformation anomalies related to strong earthquakes in the area and possible mechanism are analyzed and studied in quantitative and qualitative w4ays. In differ scale(kind) , the strong earthquake prediction index criterions based on the structure deformation anomaly are summarized.
2012, 34(2):114-120.
Abstract:Taking Biyang Sag in Henan province as example, based on the need of the pre-stack migration processing and analysis of the physical mechanism and characteristics of seismic wave scattering field in large section, a scattering wave equation forward is used. The methods for acquisition are optimization parameters model forward technique, and some technical measures for solving the excitation energy in piedmont belt of the sag. For handling method, the applications of fine velocity modeling based on pre-stack depth migration imaging method is used. For interpretation, based on visual constructed map, the distribution of steep sand-conglomerate and developmental period are analyzed, and the distribution of a new sand-conglomerate horizon zone is predicted through the groove and fan corresponding theory, combined with seismic facies analysis, the layer equalize the level of slice analysis attribute analysis and other methods etc. According to research result more wildcat are obtained successful through drilling, and two oilrich block in the southern abrupt slope belt of the sag are found.
ZHANG?Yong-liang , CHEN?Xing-chong
2012, 34(2):121-125.
Abstract:Based on the properties of multi-span simply supported girder bridges and rail system re straints on the high-speed railway, the rail-bridge into an organic whole model is established by considering rail, track slab, friction between rail and fasteners, and bridge structure. The nonlinear time history analysis method is adopted to research the influnce of rail system restraint on elasto-plastic seismic response of piers for selected spans. The results show that the effect of rail system restraint on elasto-plastic seismic response of multi-span simply supported girder bridge with relatively great differences among the height of adjacent piers is significant, so it is adviced for the case that the rail-bridge into an organic whole model should be adopted in elasto-plastic seismic response analysis.
ZHANG?Lu , QU?Guo-sheng , ZHU?Jin-fang
2012, 34(2):126-131,141.
Abstract:Based on drilling exploration cross faults, this paper presents Depth-Time (D-T) analysis method for compositing drilling section exploration. The method designs D-T graph ( depth as Y axis, time of sediment as X axis) , analyzes the defference of sedimentation speed inboth sides of fault, determines the activity time and displacement of fault. The method is applied in works of urban fault exploration in Fuzhou basin and Quanzhou basin, and brings good results. At last, the influence factors to the method are analyzed, and it is considered the key factor is flatness of terrain ( ancient terrain) of the drilling site.
LUO?Guo-fu , TU?Hong?wei , MA?He-qin , YANG?Ming-zhi
2012, 34(2):132-137.
Abstract:Using the random function theory, taking seismic energy field in the southeastern part of Gansu province to Shanxi-Gansu-Ningxia boundary region as the random function of space and time, the time "weight" coefficients and the isogram charts of first several typical fields in the region are studied by the method of natural orthogonal function expansion. The result shows that the time coefficient curves upward and downward changes with large amplitude often meaning the moderate-strong earthquake is going up, while the high values of isogram give the region of earthqake hazard.
2012, 34(2):138-141.
Abstract:Based on the optical interferometric principle, a new seismic imaging method which use seismic wave to replace optical wave, named seismic interferometric imaging method is presented. This method needn't to pick up first arrival, and can use any array detectors as the observation system. A two-dimensional time delay record from a subsurface source is simulated, and a Cbased positioning procedure for seismic source is established, then use this method to invert. The result of this program indicates that the method is feasible and high in location accuracy.
JIA?Wei , LIU?Hong-chun , LIU?Yu , YUAN?Dao-yang
2012, 34(2):142-149.
Abstract:Wudu-Kangxian fault is one of the regional faults with left-lateral strike slip and thrusting active in southeastern part of Gansu province. Through satellite image interpretation and field investigation, the geometric segmentation and geomorphological and geological characteristics of the fault are studied. The result shows that the fault zone can be divided into the west(F1 ) and east(F2) segments, named Shangbanqiao-Changba fault and Shenjiayuan-Yaoping fault. Since the late Pleistocene, fault activity has formed rich dislocation landform phenomena, such as the left lateral of streams and ridges, terminal facet, fault cliff, saddle, waterfall and ground fissures. The new active of west segment(F1) was in Holocene, occurred from (1. 730 ±0. 111) ka to (1. 670 ± 0. 141) ka ago. Its strong and obvious Holocene active characteristics are found in Ganquan town, mainly shows left-lateral strike slip accompanied by reverse component. The east segment(F2 ) may be a late Pleistocene active fault, mainly shows reverse component accompanied by the left-lateral strike slip.
XU?Kang-sheng , Li?Qiu-hong , Li?Ying
2012, 34(2):150-153.
Abstract:The continuous recorded broadband seismographics waveform data in 12 days before the Wenchuan M8.0 earthquake in 2008 from 3 seismic stations of Sichuan digital seismic network and one in 14 days before the Yushu M7.1 earthquake in 2010 from 3 seismic stations of Qinghai digital seismic network, which nearby the epicentres, are chosen and analyzed. The result shows that dominant frequence of background noise obvious changed before the two main rupure, and both cases have similar character. It indicated possible slight ruputures in the seismogenic zone before the great earthquake. Althougt it is a primary result, it is helpful to research induction machinism of earthquake and earquake prediction explore.
LIU?Wei , ZHANG?Xiao-qing , SHI?Yu-cheng , WEN?Yong , ZHAO?Yan-jie
2012, 34(2):154-160.
Abstract:Through establishing the Green function database, the calculation work in the moment tensors inversion method is reduced, and speed for getting focal mechanism solutions of moderate-small earthquakes is improved. Using this method the focal mechanism solutions for 98 events with MI≥2.0 in 2008, in Qinghai province are calculated. The result is discussed also. The research work is helpful to using regional digital seismograph network data for giving focal mecha nism solution of small earthquakes.
GONG?Wen-jun , Ii Ming-yong , WU?Zhi-jian
2012, 34(2):161-166.
Abstract:The stability of landslides under the coupling action of earthquake and rainfall is ana- lyzed with an example of No. Ⅲ landslide of Xihe county, Gansu province. We adopte Geostudio software to simulate the landslide in two conditions, i.e. natural status and the coupling influence from earthquake and rainfall. The analysis result shows that the landslide is generally stable in nature state; on the contrary, the coupling action could have serious impact on the stability of NO. Ⅲ landslide of Xihe county. The result also shows that with same calculation condition and rainfall, a certain magnitude earthquake coupling with three kinds of rainfall intensities could cause different landslide possibilities; the less rainfall intensity may cause the more reduction of the landslide stability, due to a more volume of infiltration water and a wider distributional zone of exceeding pore pressure associated with earthquake.
2012, 34(2):167-173.
Abstract:According to characteristic of geologic structure and seismic activity in I.iaoning and the neighboring area, based on the earthquake cases studies and prediction works, the warning criterions of moderate-strong earthquake in the southern Liaoning province and the Liaoning--Inner Mongolia boundary region are extracted, and the earthquake early-warning model based on timescales is constructed. All kind of indicators used in early-warning model are processed with nondimensional method by the analytic hierarchy process. The relative order of importance and weighs of each indicator are calculated. Finally, the early-warning level of moderate-strong earthquakes in Liaoning area are obtained by judgment matrix and mathematical method for matrix operation.
GU?Chun-lei , ZHANG?Yi , Gu?Zuo-wen , WANG?Xing-zhou , WANG?Lei , XU?Ru-gang , ZHU?Zhi-chun
2012, 34(2):174-179.
Abstract:We build the buffer zones with a 30 km radius from the zero-value-lines of all nents of the abnormal geomagnetic field in lithosphere of north China seismic region, and statst cal analyze all the Ms≥4.0 earthquakes in the buffer zones since 1900. The results indicate that there are close relativities among the epicenter distribution of large earthquakes with Ms≥7.0 and the zero-value-lines of geomagnetic declination, north component, east component and vertical component of the abnormal geomagnetic field, and the epicenter distribution has the highest relation to the geomagnetic declination with proportion 83.3%.
WANG?Qian , YUAN?Zhong-xia , WANG?Lan-min , HOU?Jing-rui , ZHANG Guo-xin
2012, 34(2):180-185.
Abstract:Beiyuan is a loess tableland in northeast of Linxia county, Gansu province, where the soil deposit is typical Malan loess(Q3 ). After 2008 Weuehuan Ms8.0 earthquake, cases of serious subsidence of loess ground were found within several mouths and caused substantial loss in economic. In this paper, the causes and mechanism of these large-scale subsidence of loess are analyzed through field investigation and laboratory test. It is believed that water seepage through channels which formed by connection of surface cracks developed during Wenchuan earthquake with vertical fissures in loess is the main cause. In the water seepage, water accumulates on the impermeable layer at the bottom of loess layer, and the loess partially collapsed from the bottom to the surface. To prevent such hazard, some treatment methods considering the economic condition and local suitability are proposed.
LEI?Qi-yun , CHAI?Chi-zhang , WANG?Yin , DU?Peng , MENG Guang-kui
2012, 34(2):186-191,208.
Abstract:The Xidatan buried fault is located in the north of Yinchuan basin and it is determined as one of buried faults in the active faults detection work of Shizuishan city. Based on the interpretation of seismic exploration for shallow layers, exploration of composite drilling section and core sample dating method are used to obtain some important data, such as depth of fault upper break- ing point, displacements and ages of key mark layer. The slip rates of Xidatan fault in different period of late Quaternary are finally estimated. The change of dip angle of key mark layer are found, and then, activity characteristics of Xidatan buried fault are discussed. The result shows that, with the deformation of the key mark layer, Xidatan fault ,which a low slip rate as 0. 024 mm/a, was a active fault in late Pleistocene and it's activity stop after 12 275±45 a B. P.. Not only offsets of the fault but also deformation of the key mark layer is characterized by intermittent activity. If considered these two changes as a whole, the minimum interval is 6 600 a and the maximum is 12 275 a.
LU?Hai-long , HU?Xiao-meng , WU?Jie-li , WU?Bing
2012, 34(2):192-198.
Abstract:Sedimentary-geomorphologic method is an effective way to study the kinematic laws of active fault. From the great amount of existing researchs, the main contents and progress in the research are summarized in three aspects as kinematic characteristics of active fault with vertical movement, horizontal movement and the vertical-horizontal eompositing movement. Some key techniques could be used in the sedimentary-geomorphologic method in active fault research in future are discussed also.
TANG?Mao-cang , LIAO?Liu-feng , DENG?Guo-wei , GUO?Wei-dong , HUI?xiao-ying
2012, 34(2):199-204.
Abstract:The monthly 3.2 m-depth ground temperature and rainfall fields before the Ms8.0 Wenehuan earthquake in 2008 and the Ms7.1 Yushu earthquake in 2010 are analyzed separately. The earthquake-birth 3 steps law are found also before the two cases. The time nodes for each step started in for the two respective earthquakes were Aug. 2006 and Jun. 2009 with a largest dryhot area appeared for the first step, Jul. 2007 and Jul. 2009 with a strain wave beginning for the second step, and Mar. 2008 and Mar. 2010 with the strain wave ending for the third step. We had made an earthquake prediction for Yushu case according to the earthquake-birth 3 steps law in Nov. 2009, and the result showed that the magnitude forecasted was right but the location and the time were wrong. Therefore, though the earthquake-birth 3 steps is found, we still have a long way to make a prediction success.
2012, 34(2):205-206.
Abstract:Using the waveform data from the Digital Seismological Network of Gansu province, adopting CAP method, the focal mechanism of the 5. 4 earthquake which occurred at JinTan-Alashanmeng on May 3, 2012, is obtained. It shows that the character of focus is strike-slip, the fault rupture plan is 78°, azimuth of maximum principal compressive stress, P, is N32°E, and the focal depth is 9 km.
2012, 34(2):207-208.
Abstract:
Sopyright:China Earthquake Engineering Journal