Under barometric pressure,groundwater flow in well-aquifer systems is a kind of hydro-mechanical coupling problem.Applying the flux boundary conditions on borehole wall and water pressure equilibrium conditions inside...Under barometric pressure,groundwater flow in well-aquifer systems is a kind of hydro-mechanical coupling problem.Applying the flux boundary conditions on borehole wall and water pressure equilibrium conditions inside and outside the borehole wall under barometric pressure(BP),an analytic solution to well-water level changes has been proposed in this paper.The formulation shows that the BP coefficients increase with time and tend to BP constant.The Change of BP coefficients over time depends only on the ratio of transmissivity(T) to the well radius squared(r2w),and has nothing to do with the change in BP.The BP constant only relates to aquifer loading efficiency(B),and has nothing to do with the aquifer transmissivity and well radius.The BP coefficients change over time in the analytic formulation is consistent with the analysis of measured data from the Nanxi wells.Based on the BP coefficient changes over time,a parameter estimation method is suggested and discussed in its application to the estimation of the aquifer BP constant(or B) and transmissivity by using the Nanxi well data.展开更多
In order to understand the monitoring efficiency status of the well-water-level observation network in China after the completion of the 10 th "Five-year Plan " digital network project,and to provide a basis...In order to understand the monitoring efficiency status of the well-water-level observation network in China after the completion of the 10 th "Five-year Plan " digital network project,and to provide a basis for the future network optimization and equipment updating, the monitoring efficiency of the well-water-level observation network was evaluated. On the whole,61. 8% observing stations have good monitoring effectiveness,the observation environment of 73. 5% of observing stations meets the monitoring requirements of well-water-level. The operation status of the network is as a whole getting better,operation rates of 75% observing instruments are above 95%. Most well water levels can monitor crustal stress changes and seismic activities. However,some observation stations,due to inherent deficiency in wells,environmental disturbance,instrument aging,and low-level operation and maintenance,need to improve the monitoring efficiency level by taking measures such as observation environment improvement,equipment updating,and management training. About 6. 5% of the stations need to stop observation due to the unqualified observational environment.展开更多
A lot of slow fluctuations of water level have been observed in the original recording maps of subsurface fluid in Well Shuozhou, Shanxi Province. Some typical recording maps of the "precursors" are introduc...A lot of slow fluctuations of water level have been observed in the original recording maps of subsurface fluid in Well Shuozhou, Shanxi Province. Some typical recording maps of the "precursors" are introduced in the paper and the features of the "precursors" recorded by the well are analyzed. The results show that 38% strong earthquakes possess this kind of record, which has a fluctuation period arranging from several to tens of minutes and appear mostly two days before the earthquakes. Moreover, the mechanism, transmission and responding conditions of well water level are discussed, as well as the scientific meaning and practical value of the "precursor" of the well water level in earthquake predictions.展开更多
According to the characteristics of frequent water level step-variation in the Wanquan Well, the step-variationfrequency change on the time axis can be regarded as a sequence of step-variation. A study of the relation...According to the characteristics of frequent water level step-variation in the Wanquan Well, the step-variationfrequency change on the time axis can be regarded as a sequence of step-variation. A study of the relationshipbetween the process of development and evolution of the sequential step-variation and the regional seismicityindicated that the sequential step-variation anomalies are rather better in coincidence with the time, magnitude andfrequency of regional seismic activities, which may predict the seismicity trend in months. Furthermore, on thisbasis, if the water level changes in a characteristic manner, the seismic regime during the time period from severaldays to 20 days or more may be evaluated. By using the method presented in this paper we had a prediction aboutthe Baotou ML=6.6 earthquake on May 3, 1996. This event occurred within the predicted time span but with a lessmagnitude and a little location deviation.展开更多
In this paper,the long time series data of the well water-level data of 12 wells in the Sichuan and Yunnan area is analyzed by the Baytap-G tidal analysis software,and well water level tidal response characteristic pa...In this paper,the long time series data of the well water-level data of 12 wells in the Sichuan and Yunnan area is analyzed by the Baytap-G tidal analysis software,and well water level tidal response characteristic parameters( amplitude ratio and phase change)are extracted. We analyzed the features of the shape and stage change,and characteristic parameters of the tidal response of well water level before and after the earthquakes,which can provide a new method and approach to analyzing the response relationships between well water level and earth tide and barometric pressure. The results show that Luguhu Well and 9 other wells are affected by earth tides,and their well water level amplitude ratios and phases are relatively stable; the Nanxi Well and Dayao Well water level changes are affected by the barometric pressure combined with tide force,and their well water level amplitude ratios and phases are more discrete. The water level amplitude ratios and phases of Jiangyou Well,Luguhu Well and Dongchuan Well are significant to large earthquakes,and the relationship between seismic energy density and water level amplitude ratios and phases of M_2 wave of the three wells are presented.展开更多
Coseismic water level changes which may have been induced by the Wenchuan MS8.0 earthquake and its 15 larger aftershocks(MS≥5.4) have been observed at Tangshan well.We analyze the correlation between coseismic parame...Coseismic water level changes which may have been induced by the Wenchuan MS8.0 earthquake and its 15 larger aftershocks(MS≥5.4) have been observed at Tangshan well.We analyze the correlation between coseismic parameters(maximum amplitude, duration, coseismic step and the time when the coseismic reach its maximum amplitude) and earth-quake parameters(magnitude, well-epicenter distance and depth), and then compare the time when the coseismic oscillation reaches its maximum amplitude with the seismogram from Douhe seismic station which is about 16.3 km away from Tangshan well.The analysis indicates that magnitude is the main factor influencing the induced coseismic water level changes, and that the well-epicenter distance and depth have less influence.MS magnitude has the strongest correlation with the co-seismic water level changes comparing to MW and ML magnitudes.There exists strong correlation between the maximum amplitude, step size and the oscillation duration.The water level oscillation and step are both caused by dynamic strain sourcing from seismic waves.Most of the times when the oscillations reach their maximum amplitudes are between S and Rayleigh waves.The coseismic water level changes are due to the co-effect of seismic waves and hydro-geological environments.展开更多
Choosing the Jingle well in Shanxi as the research object, this paper discusses the reproducibility problem of well water level precursor waves. The results show that the start time and fluctuation cycle before simila...Choosing the Jingle well in Shanxi as the research object, this paper discusses the reproducibility problem of well water level precursor waves. The results show that the start time and fluctuation cycle before similar earthquakes are highly reproducible,the ratio of which is up to 63. 1%. The fluctuation form and amplitude before some similar earthquakes are of certain similarity,but earthquakes with all precursor wave features being similar were not found in the research scope. The reason may be related to the origin and transmission route of the precursor wave as well as the properties of the seismic source area of similar earthquakes.展开更多
Taking five underground water level observation wells with high earthquake response capability and located in Shanxi,Hebei and Inner Mongolia as study objects,this paper studies and discusses the generality of precurs...Taking five underground water level observation wells with high earthquake response capability and located in Shanxi,Hebei and Inner Mongolia as study objects,this paper studies and discusses the generality of precursor waves in well water levels before strong earthquakes. It is indicated that the precursor waves often happen before strong earthquakes,with the ratio of occurrence up to 65% ( 41 /63 ) ; the precursor waves have poor generality in different observation wells,which may be related to the different well-aquifer system of different observation wells and the different source parameters of earthquakes. Compared to the seismic water level fluctuations in a single well,the number of precursor wave times recorded in well water levels before strong earthquakes is slightly less than that of seismic water level fluctuations,with a ratio between 39. 7% and 50. 7%, respectively. The number of observation wells with precursor wave recordings before earthquakes accounts for up to 66. 7% of the total number of observation wells. The precursor wave in well water level records has a certain generality in terms of the number of times recorded and the spatial distribution,except for its manifestation characteristics.展开更多
The water level rising rate of Tangshan mine well significantly accelerated in 2010,and the ascensional range was obviously higher than that of the same period in previous years.From the view of groundwater dynamics a...The water level rising rate of Tangshan mine well significantly accelerated in 2010,and the ascensional range was obviously higher than that of the same period in previous years.From the view of groundwater dynamics and loading effects,and based on the water pumping( pouring) water test model and semi-infinite elastic space theory model under uniform load,the effects of grouting and loading of nearby building construction on the well water level were analyzed. Results show that grouting at a distance of 200 ~ 700 m to the well,with amount of 2500m3 per day and duration of 270 d,can cause an 8 ~ 11 m rise of well water level; and loading of large-area building construction can cause about a 4m rise of well water level. Through the analysis of these factors,we find that the water level anomalous rising of Tangshan mine well was relevant to grouting and loading of the nearby building construction. This study provides a scientific basis for anomalous rising analysis of water level of Tangshan mine well.展开更多
This paper gives a description of the co-seismic and post-seismic groundwater level changes induced in Chinese mainland by the 2011 Mw9. 0 Japan earthquake,and the corresponding stress changes calculated on the assump...This paper gives a description of the co-seismic and post-seismic groundwater level changes induced in Chinese mainland by the 2011 Mw9. 0 Japan earthquake,and the corresponding stress changes calculated on the assumption of linear elasticity. The result shows that the main types of changes were oscillations and step increases. The North-South Seismic Belt and the Shanxi Seismic Belt were the main areas affected by the earthquake.展开更多
The characteristics of seismic water level fluctuations of the two Sumatra-Andaman strong earthquakes with magnitude 8.7 and 8.5 on December 26,2004 and March 29,2005 recorded at Jiaji well,Qionghai,Hainan were analyz...The characteristics of seismic water level fluctuations of the two Sumatra-Andaman strong earthquakes with magnitude 8.7 and 8.5 on December 26,2004 and March 29,2005 recorded at Jiaji well,Qionghai,Hainan were analyzed,the features of the infrequent "step" changes of well water level after the two earthquakes were also analyzed and the mechanism of the "step change" of well water level was discussed.Then the high-sample-rate digital observation data of seismically-induced water level fluctuations of the Sumatra-Andaman strong earthquakes with magnitude 8.7 and 8.5 recorded at Nanbin well,Sanya and Tanniu well,Wenchang were analyzed.The results suggest that the dominant period of the seismic well water level fluctuation in all three wells was comparatively accordant,the amplitudes of seismic water level fluctuation of the same earthquake in different wells were clearly different,the time duration of seismic water level fluctuations of different earthquakes at the same well was also clearly different.展开更多
Based on linear poroelastic and hydrogeology theory,a mathematical expression describing the relationship between water level change and aquifer volume strain is put forward.Combined with earth tidal theory,we analyze...Based on linear poroelastic and hydrogeology theory,a mathematical expression describing the relationship between water level change and aquifer volume strain is put forward.Combined with earth tidal theory,we analyze the response characteristics from well-aquifer water level change to earth tide of volume strain and present a method of volume strain inversion from water level change.Comparing the results of inversion with real observed data,we found that there is a good consistency.This suggests that the method of volume strain inversion from water level change is proper.It will offer a reference for learning about hydrogeology characteristics,volume strain and searching for precursor anomalies.展开更多
基金supported by special funds for Public Welfare Scientific Research of Ministry of Science and Technology,PRC(200808055)Scientific Research Project of Education Department,Hebei Province(Z2009104),China
文摘Under barometric pressure,groundwater flow in well-aquifer systems is a kind of hydro-mechanical coupling problem.Applying the flux boundary conditions on borehole wall and water pressure equilibrium conditions inside and outside the borehole wall under barometric pressure(BP),an analytic solution to well-water level changes has been proposed in this paper.The formulation shows that the BP coefficients increase with time and tend to BP constant.The Change of BP coefficients over time depends only on the ratio of transmissivity(T) to the well radius squared(r2w),and has nothing to do with the change in BP.The BP constant only relates to aquifer loading efficiency(B),and has nothing to do with the aquifer transmissivity and well radius.The BP coefficients change over time in the analytic formulation is consistent with the analysis of measured data from the Nanxi wells.Based on the BP coefficient changes over time,a parameter estimation method is suggested and discussed in its application to the estimation of the aquifer BP constant(or B) and transmissivity by using the Nanxi well data.
基金funded by the National Key Basic Research Program of China(Grant No.2013CB733205)
文摘In order to understand the monitoring efficiency status of the well-water-level observation network in China after the completion of the 10 th "Five-year Plan " digital network project,and to provide a basis for the future network optimization and equipment updating, the monitoring efficiency of the well-water-level observation network was evaluated. On the whole,61. 8% observing stations have good monitoring effectiveness,the observation environment of 73. 5% of observing stations meets the monitoring requirements of well-water-level. The operation status of the network is as a whole getting better,operation rates of 75% observing instruments are above 95%. Most well water levels can monitor crustal stress changes and seismic activities. However,some observation stations,due to inherent deficiency in wells,environmental disturbance,instrument aging,and low-level operation and maintenance,need to improve the monitoring efficiency level by taking measures such as observation environment improvement,equipment updating,and management training. About 6. 5% of the stations need to stop observation due to the unqualified observational environment.
基金State Natural Science Foundation of China (19973011).
文摘A lot of slow fluctuations of water level have been observed in the original recording maps of subsurface fluid in Well Shuozhou, Shanxi Province. Some typical recording maps of the "precursors" are introduced in the paper and the features of the "precursors" recorded by the well are analyzed. The results show that 38% strong earthquakes possess this kind of record, which has a fluctuation period arranging from several to tens of minutes and appear mostly two days before the earthquakes. Moreover, the mechanism, transmission and responding conditions of well water level are discussed, as well as the scientific meaning and practical value of the "precursor" of the well water level in earthquake predictions.
文摘According to the characteristics of frequent water level step-variation in the Wanquan Well, the step-variationfrequency change on the time axis can be regarded as a sequence of step-variation. A study of the relationshipbetween the process of development and evolution of the sequential step-variation and the regional seismicityindicated that the sequential step-variation anomalies are rather better in coincidence with the time, magnitude andfrequency of regional seismic activities, which may predict the seismicity trend in months. Furthermore, on thisbasis, if the water level changes in a characteristic manner, the seismic regime during the time period from severaldays to 20 days or more may be evaluated. By using the method presented in this paper we had a prediction aboutthe Baotou ML=6.6 earthquake on May 3, 1996. This event occurred within the predicted time span but with a lessmagnitude and a little location deviation.
基金sponsored by the Spark Program of Earthquake Technology of CEA in 2017(XH17026)Combination Project with Monitoring,Prediction and Scientific Research of Earthquake Technology,CEA(162205)
文摘In this paper,the long time series data of the well water-level data of 12 wells in the Sichuan and Yunnan area is analyzed by the Baytap-G tidal analysis software,and well water level tidal response characteristic parameters( amplitude ratio and phase change)are extracted. We analyzed the features of the shape and stage change,and characteristic parameters of the tidal response of well water level before and after the earthquakes,which can provide a new method and approach to analyzing the response relationships between well water level and earth tide and barometric pressure. The results show that Luguhu Well and 9 other wells are affected by earth tides,and their well water level amplitude ratios and phases are relatively stable; the Nanxi Well and Dayao Well water level changes are affected by the barometric pressure combined with tide force,and their well water level amplitude ratios and phases are more discrete. The water level amplitude ratios and phases of Jiangyou Well,Luguhu Well and Dongchuan Well are significant to large earthquakes,and the relationship between seismic energy density and water level amplitude ratios and phases of M_2 wave of the three wells are presented.
基金supported by National Natural Science Foundation of China (No. 40574020)Basic Research item of Institute of Earthquake Science, China Earthquake Administration (No. 0207690236).
文摘Coseismic water level changes which may have been induced by the Wenchuan MS8.0 earthquake and its 15 larger aftershocks(MS≥5.4) have been observed at Tangshan well.We analyze the correlation between coseismic parameters(maximum amplitude, duration, coseismic step and the time when the coseismic reach its maximum amplitude) and earth-quake parameters(magnitude, well-epicenter distance and depth), and then compare the time when the coseismic oscillation reaches its maximum amplitude with the seismogram from Douhe seismic station which is about 16.3 km away from Tangshan well.The analysis indicates that magnitude is the main factor influencing the induced coseismic water level changes, and that the well-epicenter distance and depth have less influence.MS magnitude has the strongest correlation with the co-seismic water level changes comparing to MW and ML magnitudes.There exists strong correlation between the maximum amplitude, step size and the oscillation duration.The water level oscillation and step are both caused by dynamic strain sourcing from seismic waves.Most of the times when the oscillations reach their maximum amplitudes are between S and Rayleigh waves.The coseismic water level changes are due to the co-effect of seismic waves and hydro-geological environments.
基金funded by Science and Technology Tackling Project of Shanxi Province ( 2006031106)the Joint Earthquake Science Foundation of China Earthquake Administration( A08051)Natural Sciences Foundation of Shanxi Province ( 2011011027)
文摘Choosing the Jingle well in Shanxi as the research object, this paper discusses the reproducibility problem of well water level precursor waves. The results show that the start time and fluctuation cycle before similar earthquakes are highly reproducible,the ratio of which is up to 63. 1%. The fluctuation form and amplitude before some similar earthquakes are of certain similarity,but earthquakes with all precursor wave features being similar were not found in the research scope. The reason may be related to the origin and transmission route of the precursor wave as well as the properties of the seismic source area of similar earthquakes.
基金supported jointly by the Joint Earthquake Science Foundation (A08051)Shanxi provincial key scientific and technological project (2006031106)+1 种基金Shanxi provincial natural science foundation project (2011011027)the earthquake trend tracing for 2011 (2011011401)
文摘Taking five underground water level observation wells with high earthquake response capability and located in Shanxi,Hebei and Inner Mongolia as study objects,this paper studies and discusses the generality of precursor waves in well water levels before strong earthquakes. It is indicated that the precursor waves often happen before strong earthquakes,with the ratio of occurrence up to 65% ( 41 /63 ) ; the precursor waves have poor generality in different observation wells,which may be related to the different well-aquifer system of different observation wells and the different source parameters of earthquakes. Compared to the seismic water level fluctuations in a single well,the number of precursor wave times recorded in well water levels before strong earthquakes is slightly less than that of seismic water level fluctuations,with a ratio between 39. 7% and 50. 7%, respectively. The number of observation wells with precursor wave recordings before earthquakes accounts for up to 66. 7% of the total number of observation wells. The precursor wave in well water level records has a certain generality in terms of the number of times recorded and the spatial distribution,except for its manifestation characteristics.
基金funded by the Earthquake Tracking Contract Orientated Task,CEA(2011020303)Science and Technology Project of Hebei Province(13275407D)
文摘The water level rising rate of Tangshan mine well significantly accelerated in 2010,and the ascensional range was obviously higher than that of the same period in previous years.From the view of groundwater dynamics and loading effects,and based on the water pumping( pouring) water test model and semi-infinite elastic space theory model under uniform load,the effects of grouting and loading of nearby building construction on the well water level were analyzed. Results show that grouting at a distance of 200 ~ 700 m to the well,with amount of 2500m3 per day and duration of 270 d,can cause an 8 ~ 11 m rise of well water level; and loading of large-area building construction can cause about a 4m rise of well water level. Through the analysis of these factors,we find that the water level anomalous rising of Tangshan mine well was relevant to grouting and loading of the nearby building construction. This study provides a scientific basis for anomalous rising analysis of water level of Tangshan mine well.
基金suppvroted by the research grant from the Institute of Crustal Dynamics,China Earthquake Administration ( ZDJ2011-11)
文摘This paper gives a description of the co-seismic and post-seismic groundwater level changes induced in Chinese mainland by the 2011 Mw9. 0 Japan earthquake,and the corresponding stress changes calculated on the assumption of linear elasticity. The result shows that the main types of changes were oscillations and step increases. The North-South Seismic Belt and the Shanxi Seismic Belt were the main areas affected by the earthquake.
基金sponsored by Joint Earthquake Science Foundation of China (105086)
文摘The characteristics of seismic water level fluctuations of the two Sumatra-Andaman strong earthquakes with magnitude 8.7 and 8.5 on December 26,2004 and March 29,2005 recorded at Jiaji well,Qionghai,Hainan were analyzed,the features of the infrequent "step" changes of well water level after the two earthquakes were also analyzed and the mechanism of the "step change" of well water level was discussed.Then the high-sample-rate digital observation data of seismically-induced water level fluctuations of the Sumatra-Andaman strong earthquakes with magnitude 8.7 and 8.5 recorded at Nanbin well,Sanya and Tanniu well,Wenchang were analyzed.The results suggest that the dominant period of the seismic well water level fluctuation in all three wells was comparatively accordant,the amplitudes of seismic water level fluctuation of the same earthquake in different wells were clearly different,the time duration of seismic water level fluctuations of different earthquakes at the same well was also clearly different.
基金The researchwas jointly supported by the research project entitled"Research on the Digital Data Analysis Application of Underground Fluid"under the 11th"Five-Year Plan"of China Earthquake Administration (2006BAC01B02-03-02)the Joint Earthquake Science Foundation of China Earthquake Administration (105141)
文摘Based on linear poroelastic and hydrogeology theory,a mathematical expression describing the relationship between water level change and aquifer volume strain is put forward.Combined with earth tidal theory,we analyze the response characteristics from well-aquifer water level change to earth tide of volume strain and present a method of volume strain inversion from water level change.Comparing the results of inversion with real observed data,we found that there is a good consistency.This suggests that the method of volume strain inversion from water level change is proper.It will offer a reference for learning about hydrogeology characteristics,volume strain and searching for precursor anomalies.
