基于融合的GPS速度场结果,使用DEFNODE负位错反演程序估算了喜马拉雅主逆冲断层(the main Himalayan thrust,MHT)的闭锁程度和滑动亏损空间分布,并结合剖面结果分析了断层远、近场的运动特征。结果表明,MHT的闭锁深度基本达到18~24km,...基于融合的GPS速度场结果,使用DEFNODE负位错反演程序估算了喜马拉雅主逆冲断层(the main Himalayan thrust,MHT)的闭锁程度和滑动亏损空间分布,并结合剖面结果分析了断层远、近场的运动特征。结果表明,MHT的闭锁深度基本达到18~24km,断层面闭锁宽度达到102~136km,两次历史大地震破裂区域之间的未破裂段落和未发生大地震的段落闭锁深度更深,闭锁断层面更宽,2015年尼泊尔Mw7.8大地震就发生在两次大地震破裂区域之间的段落;MHT总滑动亏损速率和垂直断层挤压滑动亏损速率自东向西逐渐减小,平行断层右旋滑动亏损速率则基本上自东向西逐渐增加;MHT 3条剖面拟合结果也反映出其存在很强的闭锁。根据估算的此次Mw7.8地震的复发周期230年和最近500多年发生的大地震分布,认为MHT整条段落尤其是尼泊尔西部与印度接壤处和可能还没有破裂的不丹地区依然有发生8级大地震的危险。展开更多
The relationship between pre-seismic anomalous changes and earthquakes is one of the most basic information to comprehend the process of earthquake preparation and conduct earthquake prediction research.However,few re...The relationship between pre-seismic anomalous changes and earthquakes is one of the most basic information to comprehend the process of earthquake preparation and conduct earthquake prediction research.However,few researchers have carried out relevant investigations for a long time.In this paper,the distribution characteristics of deformation anomalies before the Wenchuan earthquake are analyzed,and the widespread distribution area is discussed.Based on previous studies,we improve the relationship between anomaly duration t and magnitude M by introducing distance D.The new model is characterized by lower magnitude fitting error,making it possible to establish the correlation between deformation precursors and earthquakes.The correlation standard between precursors and earthquakes here is defined as Niu's criterion,which is applied to analyze and interpret the relationship between the shortterm anomalies of Hongliuxia fault leveling and the Wenchuan and Jiuzhaigou earthquakes.展开更多
In this paper, using the 1999 ~ 2007 GPS velocity field data, and by choosing the optimal block model, we obtained the deformation models applicable to the boundary zones of major blocks and the slip rates of block bo...In this paper, using the 1999 ~ 2007 GPS velocity field data, and by choosing the optimal block model, we obtained the deformation models applicable to the boundary zones of major blocks and the slip rates of block boundary faults on the mid-southern segment of the North-South Seismic Belt. The results show that： on the Longmenshan fault zone, the tensional and compressive slip rate is small on the Baoxing-Wenchuan segment, about 0. 5 ~ 1.8mm·a^-1, and the rate is relatively significant on the segment of the Wenchuan--Maoxian, as 1.8 ~3.8mm·a^-1; on the Xianshuihe fault belt, there is a certain difference in spatial distribution between the tensional slip rag.e and strike-slip rate： the tensional slip rate （ 8. lmm^a-1） is bigger than the sinistral strike-slip rate （ 4.8mm·a^-1） at the north of the Luhuo region; the tension and compression slip rate is basically the same as the strike-slip rate at Luhuo-Dawu; the Dawu-Kangding section presents a trend of decreased strike-slip rate and increased tensional slip rate; the Kangding-ghimian segment shows a strike-slip nature; the strike-slip rate is significantly greater than the tension/compression rate on the Xiaojiang fault zone; the slip rate on the Red River fault zone shows obvious spatial segmentation, the slip rate is smaller in its northwest part, but with a certain amount of tensional/compression component, 4. 7mm·a^-1 on the Jingdong segment. The segment east of Jingdong （ western Gejiu） is mainly of strike-slip, with a slip rate of 4. 5mm·a^-1.展开更多
Based on the load model of a uniform isotropic semi-infinite elastic medium,we deduced a calculation of vertical displacement and tilt and proposed a method of calculation of vertical displacements and tilts caused by...Based on the load model of a uniform isotropic semi-infinite elastic medium,we deduced a calculation of vertical displacement and tilt and proposed a method of calculation of vertical displacements and tilts caused by irregular load on the ground or underground at a certain point with two-dimensional and three-dimensional shapes. We compared the difference between the simplified model and the irregular model. Finally,the vertical displacements near the irregular load and the distribution of horizontal tilt are presented.The results show that,compared with the point simplified model,the irregular load model has certain advantages for describing the near field. The establishment of a twodimensional irregular load model can help with the calculation of the modal vector superposition after load scattering. The three-dimensional irregular load model can redistribute load through different weights given to the scattered points after the load scattering,and then obtain displacement with the vector calculation method. The results of vector superposition calculation from the scattered irregular load both in two-dimensions and three-dimensions are all convergent obviously as grids become denser,and it is shown that the calculation method is correct and feasible.展开更多
Based on the repeated gravity observation data from 1996 to 2007 from the Longmenshan gravity network, which has been dealt with by adjustment processing, the benchmark interference removal and impact of elevation cha...Based on the repeated gravity observation data from 1996 to 2007 from the Longmenshan gravity network, which has been dealt with by adjustment processing, the benchmark interference removal and impact of elevation changes removal, and by using the 3-D inversion method to reflect underground density, we analyze the characteristics of Longmenshan regional dynamic crustal density at depths of 25km, 20km and 15kin. The results show that in the Wenchuan earthquake preparation process, the regional density field showed marked characteristics both in time and space distribution. From the point of time process, the density change trend in the ten years before the earthquake presents a periodic change pattern： steady phase, dramatic stage, slow reducing phase and slow increase phase. The degree of density changes is from large to small, which means that earthquake gestation has reached the final stage. From the point of space distribution, density change distribution has a tendency of ＂dispersion--relative concentration＂, this shows that before the earthquake, the entropy of the underground density field was decreased. In addition, dramatic density changes often occur in the Longmenshan fault zone and western Sichuan plateau. Also, with the increase of depth, the trend of density change is more and more obvious. Through comparative analysis, the influence of density change on gravity is much bigger than that from height change.展开更多
文摘基于融合的GPS速度场结果,使用DEFNODE负位错反演程序估算了喜马拉雅主逆冲断层(the main Himalayan thrust,MHT)的闭锁程度和滑动亏损空间分布,并结合剖面结果分析了断层远、近场的运动特征。结果表明,MHT的闭锁深度基本达到18~24km,断层面闭锁宽度达到102~136km,两次历史大地震破裂区域之间的未破裂段落和未发生大地震的段落闭锁深度更深,闭锁断层面更宽,2015年尼泊尔Mw7.8大地震就发生在两次大地震破裂区域之间的段落;MHT总滑动亏损速率和垂直断层挤压滑动亏损速率自东向西逐渐减小,平行断层右旋滑动亏损速率则基本上自东向西逐渐增加;MHT 3条剖面拟合结果也反映出其存在很强的闭锁。根据估算的此次Mw7.8地震的复发周期230年和最近500多年发生的大地震分布,认为MHT整条段落尤其是尼泊尔西部与印度接壤处和可能还没有破裂的不丹地区依然有发生8级大地震的危险。
基金sponsered by the National Key Research and Development Program of China(2018YFC1503606)。
文摘The relationship between pre-seismic anomalous changes and earthquakes is one of the most basic information to comprehend the process of earthquake preparation and conduct earthquake prediction research.However,few researchers have carried out relevant investigations for a long time.In this paper,the distribution characteristics of deformation anomalies before the Wenchuan earthquake are analyzed,and the widespread distribution area is discussed.Based on previous studies,we improve the relationship between anomaly duration t and magnitude M by introducing distance D.The new model is characterized by lower magnitude fitting error,making it possible to establish the correlation between deformation precursors and earthquakes.The correlation standard between precursors and earthquakes here is defined as Niu's criterion,which is applied to analyze and interpret the relationship between the shortterm anomalies of Hongliuxia fault leveling and the Wenchuan and Jiuzhaigou earthquakes.
基金jointly sponsored by the National Key Technology R&D Program of the 12th "Five-year Plan" of PRC(2012BAK19B02)the Special Fund for Earthquake-related Scientific Research of China Earthquake Administration(201108009)the Youth Earthquake Regime Tracing Project for 2012(2012020212)
文摘In this paper, using the 1999 ~ 2007 GPS velocity field data, and by choosing the optimal block model, we obtained the deformation models applicable to the boundary zones of major blocks and the slip rates of block boundary faults on the mid-southern segment of the North-South Seismic Belt. The results show that： on the Longmenshan fault zone, the tensional and compressive slip rate is small on the Baoxing-Wenchuan segment, about 0. 5 ~ 1.8mm·a^-1, and the rate is relatively significant on the segment of the Wenchuan--Maoxian, as 1.8 ~3.8mm·a^-1; on the Xianshuihe fault belt, there is a certain difference in spatial distribution between the tensional slip rag.e and strike-slip rate： the tensional slip rate （ 8. lmm^a-1） is bigger than the sinistral strike-slip rate （ 4.8mm·a^-1） at the north of the Luhuo region; the tension and compression slip rate is basically the same as the strike-slip rate at Luhuo-Dawu; the Dawu-Kangding section presents a trend of decreased strike-slip rate and increased tensional slip rate; the Kangding-ghimian segment shows a strike-slip nature; the strike-slip rate is significantly greater than the tension/compression rate on the Xiaojiang fault zone; the slip rate on the Red River fault zone shows obvious spatial segmentation, the slip rate is smaller in its northwest part, but with a certain amount of tensional/compression component, 4. 7mm·a^-1 on the Jingdong segment. The segment east of Jingdong （ western Gejiu） is mainly of strike-slip, with a slip rate of 4. 5mm·a^-1.
基金funded by the Earthquake Tracing Oriented Task of Monitoring and Forecasting Department of China Earthquake Administration in 2015(2015020201):the 12th“Five-year Plan”Science and Technology Support Plan of China(2012BAK19B02)
文摘Based on the load model of a uniform isotropic semi-infinite elastic medium,we deduced a calculation of vertical displacement and tilt and proposed a method of calculation of vertical displacements and tilts caused by irregular load on the ground or underground at a certain point with two-dimensional and three-dimensional shapes. We compared the difference between the simplified model and the irregular model. Finally,the vertical displacements near the irregular load and the distribution of horizontal tilt are presented.The results show that,compared with the point simplified model,the irregular load model has certain advantages for describing the near field. The establishment of a twodimensional irregular load model can help with the calculation of the modal vector superposition after load scattering. The three-dimensional irregular load model can redistribute load through different weights given to the scattered points after the load scattering,and then obtain displacement with the vector calculation method. The results of vector superposition calculation from the scattered irregular load both in two-dimensions and three-dimensions are all convergent obviously as grids become denser,and it is shown that the calculation method is correct and feasible.
基金funded by the National Natural Science Foundation of China(41330314)Projects of Science for Earthquake Resilience(XH15049Y)+1 种基金National Science and Technology Support Program of China(2012BAK19B02,2012BAK19B03)Special Research Foundation for Seismology(201108009)
文摘Based on the repeated gravity observation data from 1996 to 2007 from the Longmenshan gravity network, which has been dealt with by adjustment processing, the benchmark interference removal and impact of elevation changes removal, and by using the 3-D inversion method to reflect underground density, we analyze the characteristics of Longmenshan regional dynamic crustal density at depths of 25km, 20km and 15kin. The results show that in the Wenchuan earthquake preparation process, the regional density field showed marked characteristics both in time and space distribution. From the point of time process, the density change trend in the ten years before the earthquake presents a periodic change pattern： steady phase, dramatic stage, slow reducing phase and slow increase phase. The degree of density changes is from large to small, which means that earthquake gestation has reached the final stage. From the point of space distribution, density change distribution has a tendency of ＂dispersion--relative concentration＂, this shows that before the earthquake, the entropy of the underground density field was decreased. In addition, dramatic density changes often occur in the Longmenshan fault zone and western Sichuan plateau. Also, with the increase of depth, the trend of density change is more and more obvious. Through comparative analysis, the influence of density change on gravity is much bigger than that from height change.
