Using data from five SGs at four stations in Chinese mainland,obvious permanent gravity changes caused by the 2015 MW7.8 Nepal(Gorkha)earthquake were detected.We analyzed the gravity effects from ground vertical defor...Using data from five SGs at four stations in Chinese mainland,obvious permanent gravity changes caused by the 2015 MW7.8 Nepal(Gorkha)earthquake were detected.We analyzed the gravity effects from ground vertical deformation(VD)using co-site continuous GPS(cGPS)data collocated at the Lijiang and the Wuhan station,and hydrological effects using GLDAS models and groundwater level records.After removing these effects,SG observations before and after the earthquake revealed obvious permanent gravity changes:−3.0μGal,7.3μGal and 8.0μGal at Lhasa,Lijiang and Wuhan station,respectively.We found that the gravity changes cannot be explained by the results of dislocation theory.展开更多
We obtained the displacement and deformation caused by the 2015 Nepal MS8. 1 earthquake adopting the finite element method,and analyzed the displacement and deformation characteristics and effect of three large earthq...We obtained the displacement and deformation caused by the 2015 Nepal MS8. 1 earthquake adopting the finite element method,and analyzed the displacement and deformation characteristics and effect of three large earthquakes on seismic activity in the Qinghai-Tibetan block. Our primary results suggest southward movement of the QinghaiTibetan block is caused by a large earthquake occurring on thrust fault in the Himalayan zone,the displacement direction is reverse to the background displacement. The occurrence of these large earthquakes will result in stress unloading and earthquake activity will be weakened in stress unloading areas. Through the simulation results,we can detect the distribution area of stress loading and unloading caused by large earthquakes.Simultaneously,it provides a fundamental evidence for determination of earthquake activity trend.展开更多
After the 2015 M_S8. 1 Nepal earthquake,a strong and moderate seismicity belt has formed in Tibet gradually spreading along the northeast direction. In this paper,we attempt to summarize the features and investigate t...After the 2015 M_S8. 1 Nepal earthquake,a strong and moderate seismicity belt has formed in Tibet gradually spreading along the northeast direction. In this paper,we attempt to summarize the features and investigate the primary mechanism of this behavior of seismic activity,using a 2-D finite element numerical model with tectonic dynamic settings and GPS horizontal displacements as the constraints. In addition,compared with the NEtrending seismicity belt triggered by the 1996 Xiatongmoin earthquake,we discuss the future earthquake hazard in and around Tibet. Our results show that: the NE-directed seismicity belt is the response of enhanced loading on the anisotropic Qinghai-Tibetan plateau from the Indian plate and earthquake thrusting. Also,this possibly implies that a forthcoming strong earthquake may fill in the gaps in the NE-directed seismicity belt or enhance the seismic hazard in the eastern( the north-south seismic zone) and western( Tianshan tectonic region) parts near the NE-directed belt.展开更多
As a result of the two major earthquakes that struck Nepal at 11:56 am on 25 April, and 12 May 2015, nearly 9,000 lives and over half a million homes have been destroyed. In this connection, the paper tries to assess ...As a result of the two major earthquakes that struck Nepal at 11:56 am on 25 April, and 12 May 2015, nearly 9,000 lives and over half a million homes have been destroyed. In this connection, the paper tries to assess the socio- demographic impact of Nepal earthquake 2015 with reference to Sindhuli district. The Sindhuli district of Nepal was one of the highly affected districts among the fourteen severely destructed districts of the central part of Nepal, was purposively selected among them for the study purpose. The paper utilized the both primary and secondary data. The survey found that the earthquakes had unevenly affected the age, gender, poorer, rural locations relative to the urban and less poor areas. It also found that women and children had comparatively fallen victim to anxiety, trauma, depression, feeling helpless, loss of interest (passive) and irrational fear. During the survey, the study found that the NGOs, INGOs, Private and Personal support agencies/actors had played significant role in distribution of relief package at Sindhuli district of Nepal. The distributions of relief materials were challenging because of lack of road connectivity to reach at many earthquake affected villages in Sindhuli district.展开更多
2015年4月25日青藏高原南缘的喜马拉雅地震带发生尼泊尔M_S8.1大地震,中国藏南区域和尼泊尔境内的GPS连续站均观测到了明显的同震和震后形变。收集中国大陆构造环境监测网络藏南区域GPS基准站和尼泊尔境内的GPS连续观测站数据,采用统一...2015年4月25日青藏高原南缘的喜马拉雅地震带发生尼泊尔M_S8.1大地震,中国藏南区域和尼泊尔境内的GPS连续站均观测到了明显的同震和震后形变。收集中国大陆构造环境监测网络藏南区域GPS基准站和尼泊尔境内的GPS连续观测站数据,采用统一策略精密解算后获得了测站坐标时序。利用震前两年以上的数据拟合测站长期构造运动和周期性非构造运动,并从震后的时间序列扣除之后获得了GPS测站的震后形变。采用震后余滑的对数型模型、粘弹性松弛的指数型模型以及二者组合的综合模型等3种震后形变模型拟合了GPS测站观测到的震后形变。采用基于贝叶斯估计的马尔科夫链蒙特卡洛(Markov Chain Monte Carlo,MCMC)算法反演了模型参数。结果显示,对数型模型加指数型模型的综合模型能够更好地拟合GPS观测到的震后形变,表明GPS观测到的震后形变至少包含两种不同的变形机制,具有多尺度特征。指数型模型的特征时间为876.623年,对应的等效粘滞系数为8.30×10^(20) Pa·s。对比不同测站两年内所积累的震后形变与同震比值,相比震中附近的测站,中国藏南区域GPS测站观测到的震后形变所占比例更高,可能指示喜马拉雅地震带主要断裂的持续性加载,其地震危险性值得进一步关注。展开更多
Frequent landslide events affect the Kathmandu Kyirong Highway(KKH),one of the most strategic Sino-Nepal highways,with multiple social effects.Amongst them,the impacts on local tourism,although being substantial,have ...Frequent landslide events affect the Kathmandu Kyirong Highway(KKH),one of the most strategic Sino-Nepal highways,with multiple social effects.Amongst them,the impacts on local tourism,although being substantial,have not been studied so far.The aim of this research is to analyze the characteristics of such landslides and their influence on road damages and/or blockages as well as on local tourism industry.We analyzed the co-seismic landslides triggered by the Gorkha Earthquake,2015(7.8 Mw),the post-seismic landslides that occurred during the monsoons following the earthquake,as well as landslides which occurred or reactivated in 2018,with relation to the damage that they caused to the highway.High resolution satellite images from 2015 to 2018,and field data were used for the analysis.The Langtang avalanche that locates off the highway was also mapped due to its high impacts on tourism.Between 2015 and 2018,the number of road damaging landslides in the Betrawati-Rasuwagadhi section of KKH(where Dhunche and Syafrubesi towns are located)was 101 in the main track(MT)and 103 in the new track(NT),with respective average density of 1.46/km and 3.63/km.The dominant observed landslide types were debris slides and rock falls.Landslides were mostly concentrated in the locations with the following characteristics:1)having higher elevated area,2)being located with the‘main central thrust’and other lineaments’belts,3)belonging to the Proterozoic lesser Himalayan rocks,4)having a slope gradient of 25°-45°,5)having northern,western and southern slope aspect,6)being subjected to average annual rainfall of higher than 1,000 mm,and 7)having less than 4 km distance from the past earthquake epicenters.The results further indicated that 7 rain-induced and 4 co-and post-seismic landslides have great impact on tourist flows.An impact analysis was also assessed through a door to door questionnaire survey with local hotel operators from Dhunche and Syafrubesi towns(n=29+31).The results reveal that out of six rigorously affected sectors by landslides leading to road blockage,tourism business is the most impacted livelihood sector in these towns.The reduction of visitors in different hotels ranged from 50%-100%in Dhunche and 70%-100%in Syafrubesi for the first year aftermath of the tremor.This is higher than the respective 5%-50%tourist reduction due to raininduced landslides.Using as a reference the base year 2014,the income loss of hotels in both towns was found to be 50%-100%in 2015,20%-100%in 2016,5%-75%in 2017,and similar to 35%in 2018.These results provide insights on the synergic effect of contributing factors for cut slope as well as down slope instability along mountainous motorways and their impact on income sources for local communities.展开更多
Koshi River basin, which lies in the Central Himalayas with an area of 71,500 km2, is an important trans-boundary river basin shared by China, Nepal and India. Yet, landslide-prone areas are all located in China and N...Koshi River basin, which lies in the Central Himalayas with an area of 71,500 km2, is an important trans-boundary river basin shared by China, Nepal and India. Yet, landslide-prone areas are all located in China and Nepal, imposing alarming risks of widespread damages to property and loss of human life in both countries. Against this backdrop, this research, by utilizing remote sensing images and topographic maps, has identified a total number of 6877 landslides for the past 23 years and further examined their distribution, characteristics and causes. Analysis shows that the two-step topography in the Himalayan region has a considerable effect on the distribution of landslides in this area. Dense distribution of landslides falls into two regions: the Lesser Himalaya(mostly small and medium size landslides in east-west direction) and the TransitionBelt(mostly large and medium size landslides along the river in north-south direction). Landslides decrease against the elevation while the southern slopes of the Himalayas have more landslides than its northern side. Change analysis was carried out by comparing landslide distribution data of 1992, 2010 and 2015 in the Koshi River basin. The rainfallinduced landslides, usually small and shallow and occurring more frequently in regions with an elevation lower than 1000 m, are common in the south and south-east slopes due to heavy precipitation in the region, and are more prone to the slope gradient of 20°~30°. Most of them are distributed in Proterozoic stratum(Pt3ε, Pt3 and Pt2-3) and Quaternary stratum. While for earthquake-induced landslides, they are more prone to higher elevations(2000~3000 m) and steeper slopes(40°~50°).展开更多
基金supported by the National Natural Science Foundation of China(No.41774093).
文摘Using data from five SGs at four stations in Chinese mainland,obvious permanent gravity changes caused by the 2015 MW7.8 Nepal(Gorkha)earthquake were detected.We analyzed the gravity effects from ground vertical deformation(VD)using co-site continuous GPS(cGPS)data collocated at the Lijiang and the Wuhan station,and hydrological effects using GLDAS models and groundwater level records.After removing these effects,SG observations before and after the earthquake revealed obvious permanent gravity changes:−3.0μGal,7.3μGal and 8.0μGal at Lhasa,Lijiang and Wuhan station,respectively.We found that the gravity changes cannot be explained by the results of dislocation theory.
基金sponsored by the Science for Earthquake Resilience(XH17039)the National Social Science Foundation of China(41574044)
文摘We obtained the displacement and deformation caused by the 2015 Nepal MS8. 1 earthquake adopting the finite element method,and analyzed the displacement and deformation characteristics and effect of three large earthquakes on seismic activity in the Qinghai-Tibetan block. Our primary results suggest southward movement of the QinghaiTibetan block is caused by a large earthquake occurring on thrust fault in the Himalayan zone,the displacement direction is reverse to the background displacement. The occurrence of these large earthquakes will result in stress unloading and earthquake activity will be weakened in stress unloading areas. Through the simulation results,we can detect the distribution area of stress loading and unloading caused by large earthquakes.Simultaneously,it provides a fundamental evidence for determination of earthquake activity trend.
基金funded by China Comprehensive Geophysical Field Observation in North China of Earthquake Scientific Research(201508009)
文摘After the 2015 M_S8. 1 Nepal earthquake,a strong and moderate seismicity belt has formed in Tibet gradually spreading along the northeast direction. In this paper,we attempt to summarize the features and investigate the primary mechanism of this behavior of seismic activity,using a 2-D finite element numerical model with tectonic dynamic settings and GPS horizontal displacements as the constraints. In addition,compared with the NEtrending seismicity belt triggered by the 1996 Xiatongmoin earthquake,we discuss the future earthquake hazard in and around Tibet. Our results show that: the NE-directed seismicity belt is the response of enhanced loading on the anisotropic Qinghai-Tibetan plateau from the Indian plate and earthquake thrusting. Also,this possibly implies that a forthcoming strong earthquake may fill in the gaps in the NE-directed seismicity belt or enhance the seismic hazard in the eastern( the north-south seismic zone) and western( Tianshan tectonic region) parts near the NE-directed belt.
文摘As a result of the two major earthquakes that struck Nepal at 11:56 am on 25 April, and 12 May 2015, nearly 9,000 lives and over half a million homes have been destroyed. In this connection, the paper tries to assess the socio- demographic impact of Nepal earthquake 2015 with reference to Sindhuli district. The Sindhuli district of Nepal was one of the highly affected districts among the fourteen severely destructed districts of the central part of Nepal, was purposively selected among them for the study purpose. The paper utilized the both primary and secondary data. The survey found that the earthquakes had unevenly affected the age, gender, poorer, rural locations relative to the urban and less poor areas. It also found that women and children had comparatively fallen victim to anxiety, trauma, depression, feeling helpless, loss of interest (passive) and irrational fear. During the survey, the study found that the NGOs, INGOs, Private and Personal support agencies/actors had played significant role in distribution of relief package at Sindhuli district of Nepal. The distributions of relief materials were challenging because of lack of road connectivity to reach at many earthquake affected villages in Sindhuli district.
文摘2015年4月25日青藏高原南缘的喜马拉雅地震带发生尼泊尔M_S8.1大地震,中国藏南区域和尼泊尔境内的GPS连续站均观测到了明显的同震和震后形变。收集中国大陆构造环境监测网络藏南区域GPS基准站和尼泊尔境内的GPS连续观测站数据,采用统一策略精密解算后获得了测站坐标时序。利用震前两年以上的数据拟合测站长期构造运动和周期性非构造运动,并从震后的时间序列扣除之后获得了GPS测站的震后形变。采用震后余滑的对数型模型、粘弹性松弛的指数型模型以及二者组合的综合模型等3种震后形变模型拟合了GPS测站观测到的震后形变。采用基于贝叶斯估计的马尔科夫链蒙特卡洛(Markov Chain Monte Carlo,MCMC)算法反演了模型参数。结果显示,对数型模型加指数型模型的综合模型能够更好地拟合GPS观测到的震后形变,表明GPS观测到的震后形变至少包含两种不同的变形机制,具有多尺度特征。指数型模型的特征时间为876.623年,对应的等效粘滞系数为8.30×10^(20) Pa·s。对比不同测站两年内所积累的震后形变与同震比值,相比震中附近的测站,中国藏南区域GPS测站观测到的震后形变所占比例更高,可能指示喜马拉雅地震带主要断裂的持续性加载,其地震危险性值得进一步关注。
基金financial support from Major International(Regional)Joint Research Project(Grant No.41520104002)Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDY-SSW-DQC006)+3 种基金International Partnership Program of Chinese Academy of Sciences(grant number 131551KYSB20180042)Strategic Priority Research Program of Chinese Academy of Sciences(Grant No XDA20030301)Organization for women in Science for Developing World(OWSD)Swedish International Development Corporation Agency(SIDA)。
文摘Frequent landslide events affect the Kathmandu Kyirong Highway(KKH),one of the most strategic Sino-Nepal highways,with multiple social effects.Amongst them,the impacts on local tourism,although being substantial,have not been studied so far.The aim of this research is to analyze the characteristics of such landslides and their influence on road damages and/or blockages as well as on local tourism industry.We analyzed the co-seismic landslides triggered by the Gorkha Earthquake,2015(7.8 Mw),the post-seismic landslides that occurred during the monsoons following the earthquake,as well as landslides which occurred or reactivated in 2018,with relation to the damage that they caused to the highway.High resolution satellite images from 2015 to 2018,and field data were used for the analysis.The Langtang avalanche that locates off the highway was also mapped due to its high impacts on tourism.Between 2015 and 2018,the number of road damaging landslides in the Betrawati-Rasuwagadhi section of KKH(where Dhunche and Syafrubesi towns are located)was 101 in the main track(MT)and 103 in the new track(NT),with respective average density of 1.46/km and 3.63/km.The dominant observed landslide types were debris slides and rock falls.Landslides were mostly concentrated in the locations with the following characteristics:1)having higher elevated area,2)being located with the‘main central thrust’and other lineaments’belts,3)belonging to the Proterozoic lesser Himalayan rocks,4)having a slope gradient of 25°-45°,5)having northern,western and southern slope aspect,6)being subjected to average annual rainfall of higher than 1,000 mm,and 7)having less than 4 km distance from the past earthquake epicenters.The results further indicated that 7 rain-induced and 4 co-and post-seismic landslides have great impact on tourist flows.An impact analysis was also assessed through a door to door questionnaire survey with local hotel operators from Dhunche and Syafrubesi towns(n=29+31).The results reveal that out of six rigorously affected sectors by landslides leading to road blockage,tourism business is the most impacted livelihood sector in these towns.The reduction of visitors in different hotels ranged from 50%-100%in Dhunche and 70%-100%in Syafrubesi for the first year aftermath of the tremor.This is higher than the respective 5%-50%tourist reduction due to raininduced landslides.Using as a reference the base year 2014,the income loss of hotels in both towns was found to be 50%-100%in 2015,20%-100%in 2016,5%-75%in 2017,and similar to 35%in 2018.These results provide insights on the synergic effect of contributing factors for cut slope as well as down slope instability along mountainous motorways and their impact on income sources for local communities.
基金supported by the National Natural Science Foundation of China(Grant No.41401007)the Key Research Program of the Chinese Academy of Sciences(Grant No.KZZD-EW-08-01)+1 种基金jointly supported by the Australian government funded Koshi Basin Programme at ICIMODICIMOD’s core funds contributed by the governments of Afghanistan,Australia,Austria,Bangladesh,Bhutan,China,India,Myanmar,Nepal,Norway,Pakistan,Switzerland,and theUnited Kingdom
文摘Koshi River basin, which lies in the Central Himalayas with an area of 71,500 km2, is an important trans-boundary river basin shared by China, Nepal and India. Yet, landslide-prone areas are all located in China and Nepal, imposing alarming risks of widespread damages to property and loss of human life in both countries. Against this backdrop, this research, by utilizing remote sensing images and topographic maps, has identified a total number of 6877 landslides for the past 23 years and further examined their distribution, characteristics and causes. Analysis shows that the two-step topography in the Himalayan region has a considerable effect on the distribution of landslides in this area. Dense distribution of landslides falls into two regions: the Lesser Himalaya(mostly small and medium size landslides in east-west direction) and the TransitionBelt(mostly large and medium size landslides along the river in north-south direction). Landslides decrease against the elevation while the southern slopes of the Himalayas have more landslides than its northern side. Change analysis was carried out by comparing landslide distribution data of 1992, 2010 and 2015 in the Koshi River basin. The rainfallinduced landslides, usually small and shallow and occurring more frequently in regions with an elevation lower than 1000 m, are common in the south and south-east slopes due to heavy precipitation in the region, and are more prone to the slope gradient of 20°~30°. Most of them are distributed in Proterozoic stratum(Pt3ε, Pt3 and Pt2-3) and Quaternary stratum. While for earthquake-induced landslides, they are more prone to higher elevations(2000~3000 m) and steeper slopes(40°~50°).
