The geomagnetic vertical transfer functions(VTFs)are useful to constrain the conductivity structure in the deep Earth.In this study,we propose an approach of estimating the geomagnetic VTFs in the wide:period range fr...The geomagnetic vertical transfer functions(VTFs)are useful to constrain the conductivity structure in the deep Earth.In this study,we propose an approach of estimating the geomagnetic VTFs in the wide:period range from the multi-interval geomagnetic data.Applying the above method to the different interval(such as one-second,one-minute,one-hour)data from some geomagnetic observatories in China,we obtain the corresponding VTFs in the wide period range from 64 s to 9,830,400 s.In order to evaluate the possible ocean effect on different observatories,we make close investigations of the real geomagnetic induction vectors at QZH,SYG and XIC observatories.The results indicate that the ocean effect is clear at the coastal observatory like QZH.However,the ocean effect tends to decrease for the inland observatories(such as SYG and XIC)with the increasing distance from the coast.展开更多
A temporary profile from Shiquan in the southern part of Shaanxi Province to Ningxian in Gansu Province for observation of geomagnetic short period variations was set up. The characteristics of geomagnetic short perio...A temporary profile from Shiquan in the southern part of Shaanxi Province to Ningxian in Gansu Province for observation of geomagnetic short period variations was set up. The characteristics of geomagnetic short period variations in the profile region was analyzed through geomagnetic transfer functions at measurement sites (Fan, et al, 1998). According to the theory of multi-scale analysis of wavelet transform, the components affected by regional origin in the region is extracted in this paper. The components of regional origin is used as original data in the inversion study for investigation of 2-D conductivity structure corresponding to the regional origin. The inversion method (Zhdanov, Traynin, 1997) which is based on the minimum of the total energy of the residual field between observational electro-magnetic field and the calculated theoretical field of conductivity model and the conception of migrated residual field is introduced into our inversion of the data of magneto-variation sounding. The result of the inversion gives the underground conductivity structure in depth range of 100 km beneath the profile, and shows that a high conductivity area is located under Wugong and Qianling. The main characteristics of the inversion method is briefly discussed, that is, it can reflect the depth and the distribution of anomalous conductivity area comparatively well, and large number of parameters of inversion model is allowed to be used in the Inversion.展开更多
In order to investigate the characteristics of short period geomagnetic variations in Shaanxi region, a temporary measurement profile from Shiquan in the southern part of Shaanxi to Ningxian in Gansu was set up in Sep...In order to investigate the characteristics of short period geomagnetic variations in Shaanxi region, a temporary measurement profile from Shiquan in the southern part of Shaanxi to Ningxian in Gansu was set up in September of 1996 to carry out simultaneous observation of three component geomagnetic variations along the profile. The vertical transfer functions, the horizontal transfer functions and the spectral component′s relationship of each period segment at each site in the period range from 3 min to 2 h were statistically calculated. Random data theory was applied to the data processing for reference, which led to a relatively good result. Analysis of the data point out that short period geomagnetic variations are affected by the regional influence of underground anomalous inductive current concentration between Wugong and Qianling in the nearly E W direction and by the influence of local inductive current in nearby area of measurement site. The main distribution feature is that vertical transfer functions reverse between Wugong and Qianling and frequency responses of the transfer functions have maximum at period about 20 min.展开更多
This paper has presented a research on the method of using digitized data of geomagnetic pulsation observation to predict earthquakes and the research results.According to the theory of inductive magnetic effect,the o...This paper has presented a research on the method of using digitized data of geomagnetic pulsation observation to predict earthquakes and the research results.According to the theory of inductive magnetic effect,the observation of geomagnetic pulsation events can detect the preseismic conductivity and structure anomalies of subsurface media more effectively than the conventional geomagnetic observations,especially the short-impending anomalies before earthquakes.Our research results have also indicated that the geomagnetic pulsation transfer function has obvious short-impending anomalies and typical anomaly forms before earthquakes.Using the proposed method,satisfactory prediction results have been obtained.展开更多
基金the National Key Research and Development Program of China(No.2018YFC1503806)the National Natural Science Foundation of China(No.41774085)。
文摘The geomagnetic vertical transfer functions(VTFs)are useful to constrain the conductivity structure in the deep Earth.In this study,we propose an approach of estimating the geomagnetic VTFs in the wide:period range from the multi-interval geomagnetic data.Applying the above method to the different interval(such as one-second,one-minute,one-hour)data from some geomagnetic observatories in China,we obtain the corresponding VTFs in the wide period range from 64 s to 9,830,400 s.In order to evaluate the possible ocean effect on different observatories,we make close investigations of the real geomagnetic induction vectors at QZH,SYG and XIC observatories.The results indicate that the ocean effect is clear at the coastal observatory like QZH.However,the ocean effect tends to decrease for the inland observatories(such as SYG and XIC)with the increasing distance from the coast.
文摘A temporary profile from Shiquan in the southern part of Shaanxi Province to Ningxian in Gansu Province for observation of geomagnetic short period variations was set up. The characteristics of geomagnetic short period variations in the profile region was analyzed through geomagnetic transfer functions at measurement sites (Fan, et al, 1998). According to the theory of multi-scale analysis of wavelet transform, the components affected by regional origin in the region is extracted in this paper. The components of regional origin is used as original data in the inversion study for investigation of 2-D conductivity structure corresponding to the regional origin. The inversion method (Zhdanov, Traynin, 1997) which is based on the minimum of the total energy of the residual field between observational electro-magnetic field and the calculated theoretical field of conductivity model and the conception of migrated residual field is introduced into our inversion of the data of magneto-variation sounding. The result of the inversion gives the underground conductivity structure in depth range of 100 km beneath the profile, and shows that a high conductivity area is located under Wugong and Qianling. The main characteristics of the inversion method is briefly discussed, that is, it can reflect the depth and the distribution of anomalous conductivity area comparatively well, and large number of parameters of inversion model is allowed to be used in the Inversion.
文摘In order to investigate the characteristics of short period geomagnetic variations in Shaanxi region, a temporary measurement profile from Shiquan in the southern part of Shaanxi to Ningxian in Gansu was set up in September of 1996 to carry out simultaneous observation of three component geomagnetic variations along the profile. The vertical transfer functions, the horizontal transfer functions and the spectral component′s relationship of each period segment at each site in the period range from 3 min to 2 h were statistically calculated. Random data theory was applied to the data processing for reference, which led to a relatively good result. Analysis of the data point out that short period geomagnetic variations are affected by the regional influence of underground anomalous inductive current concentration between Wugong and Qianling in the nearly E W direction and by the influence of local inductive current in nearby area of measurement site. The main distribution feature is that vertical transfer functions reverse between Wugong and Qianling and frequency responses of the transfer functions have maximum at period about 20 min.
文摘This paper has presented a research on the method of using digitized data of geomagnetic pulsation observation to predict earthquakes and the research results.According to the theory of inductive magnetic effect,the observation of geomagnetic pulsation events can detect the preseismic conductivity and structure anomalies of subsurface media more effectively than the conventional geomagnetic observations,especially the short-impending anomalies before earthquakes.Our research results have also indicated that the geomagnetic pulsation transfer function has obvious short-impending anomalies and typical anomaly forms before earthquakes.Using the proposed method,satisfactory prediction results have been obtained.
