This paper presents a comprehensive area expansion prediction index method to apply GNSS for short-impending prediction of earthquakes. Based on continuous GNSS observation data from Yunnan Province, a displacement fi...This paper presents a comprehensive area expansion prediction index method to apply GNSS for short-impending prediction of earthquakes. Based on continuous GNSS observation data from Yunnan Province, a displacement field was detected after data cycle-slip repair using precision data processing software and geophysical field effect model correction. The Yunnan area was divided into 56 grid cells for displacement field interpolation to obtain a more uniform displacement field and a strain field variation time series. The pre-earthquake response of each grid-cell expansion time series was evaluated and synthesized to extract a short-impending earthquake anomaly identification index. The results show that this index indicated occurrence times and hypocenter for earthquakes of magnitude M≥5. Fourteen earthquakes were predicted accurately, and there were five false reports. This index can therefore be used for the short-impending prediction of earthquakes.展开更多
In order to quantitatively describe the geoelectric precursor anomaly in the short-impending process of earthquakes, a new geoelectric precursor index — (monthly) relative change rate of ground resistivity, R ρ...In order to quantitatively describe the geoelectric precursor anomaly in the short-impending process of earthquakes, a new geoelectric precursor index — (monthly) relative change rate of ground resistivity, R ρ (t) , is designed. Using this index and choosing the internationally accepted ground resistivity data before the Tangshan M =7.8 earthquake of July 28, 1976, the features of dynamic evolution pattern of R ρ(t) are studied. The results show that: ① about 10～9 months before earthquake, the ground resistivity in a certain range around the epicentral region begins to display the anomaly of accelerating descent, and the rate of descent is higher in the epicentral region than in surrounding areas; ② with the shortening of countdown before earthquake, the R ρ(t) value in epicentral region increases gradually (ground resistivity value decreases at an increasing rate); ③ the R ρ(t) value has the epicentral area as a center and its contour lines propagate towards surrounding areas with the shortening of countdown before earthquake; ④after the R ρ(t) value in epicentral region has descended at increasing rate to reach an extremity [ R ρ(t) = (7.0], it turns to descend at decreasing rate (2～3 months) and earthquake occurs when it accelerates again. Meanwhile, earthquake occurs when the contour lines of R ρ(t) stop propagating towards surrounding areas and turn to shrink back (2～3 months later). Its physical process can be explained by the″ swollen hypothesis″ of Prof. Fu and the theory of ″Slip-weakening and rockmass instability″ of Mei, Niu, et al ..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
Located in an earthquake-prone region,the geological structures in Yunnan Province are complex. Taking into account that Tonghai county is located in the intersection of Xiaojiang fault and Honghe fault, an ACF-4M ELF...Located in an earthquake-prone region,the geological structures in Yunnan Province are complex. Taking into account that Tonghai county is located in the intersection of Xiaojiang fault and Honghe fault, an ACF-4M ELF electromagnetic instrument was installed at the Tonghai seismic station,which has produced continuous reliable data. The author collected the data and information for the year 2009 and 2010,and performed analysis on the variation characteristics of both geomagnetic fields and electrical resistivity. The result shows that the 1Hz and 39Hz electromagnetic power spectra are 0. 2 to 1. 4 orders of magnitude higher than the normal values immediately before many earthquakes. The anomalies are represented by the abrupt changes of the electric and magnetic field power spectra in earthquake and aftershock sequences,and the amplitude of change is related to the size of earthquake magnitude and epicentral distance. The electrical resistivity also obviously changes. Therefore, further research on the anomalous characteristics of ELF electromagnetic data will be meaningful to the future use of this instrument in earthquake prediction.展开更多
基金supported by the National 973 Project of China (No. 2013CB733303)the National Natural Science Foundation of China (No. 41474093)+4 种基金the Key Natural Science Foundation of Hubei Province (No. 2014CFA110)the open fund of Key Laboratory of Geospace Environment and Geodesy, Ministry of Education (No. 15-02-07)the China Earthquake Administration’s Earthquake Science and Technology Spark Program (No. XH15037SX)Special fund of earthquake science and technology of Yunnan Earthquake Agency (No. 2017ZX02)the Jiancheng Li Academician Workstation (No. 2015IC015)
文摘This paper presents a comprehensive area expansion prediction index method to apply GNSS for short-impending prediction of earthquakes. Based on continuous GNSS observation data from Yunnan Province, a displacement field was detected after data cycle-slip repair using precision data processing software and geophysical field effect model correction. The Yunnan area was divided into 56 grid cells for displacement field interpolation to obtain a more uniform displacement field and a strain field variation time series. The pre-earthquake response of each grid-cell expansion time series was evaluated and synthesized to extract a short-impending earthquake anomaly identification index. The results show that this index indicated occurrence times and hypocenter for earthquakes of magnitude M≥5. Fourteen earthquakes were predicted accurately, and there were five false reports. This index can therefore be used for the short-impending prediction of earthquakes.
文摘In order to quantitatively describe the geoelectric precursor anomaly in the short-impending process of earthquakes, a new geoelectric precursor index — (monthly) relative change rate of ground resistivity, R ρ (t) , is designed. Using this index and choosing the internationally accepted ground resistivity data before the Tangshan M =7.8 earthquake of July 28, 1976, the features of dynamic evolution pattern of R ρ(t) are studied. The results show that: ① about 10～9 months before earthquake, the ground resistivity in a certain range around the epicentral region begins to display the anomaly of accelerating descent, and the rate of descent is higher in the epicentral region than in surrounding areas; ② with the shortening of countdown before earthquake, the R ρ(t) value in epicentral region increases gradually (ground resistivity value decreases at an increasing rate); ③ the R ρ(t) value has the epicentral area as a center and its contour lines propagate towards surrounding areas with the shortening of countdown before earthquake; ④after the R ρ(t) value in epicentral region has descended at increasing rate to reach an extremity [ R ρ(t) = (7.0], it turns to descend at decreasing rate (2～3 months) and earthquake occurs when it accelerates again. Meanwhile, earthquake occurs when the contour lines of R ρ(t) stop propagating towards surrounding areas and turn to shrink back (2～3 months later). Its physical process can be explained by the″ swollen hypothesis″ of Prof. Fu and the theory of ″Slip-weakening and rockmass instability″ of Mei, Niu, et al ..
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.
基金funded by Seismic Monitoring,Prediction and Research Project"The Application of Ultra Low Frequency Electromagnetic Observation in Yunnan and Its Adjacent Region"of China Earthquake Administration in 2010
文摘Located in an earthquake-prone region,the geological structures in Yunnan Province are complex. Taking into account that Tonghai county is located in the intersection of Xiaojiang fault and Honghe fault, an ACF-4M ELF electromagnetic instrument was installed at the Tonghai seismic station,which has produced continuous reliable data. The author collected the data and information for the year 2009 and 2010,and performed analysis on the variation characteristics of both geomagnetic fields and electrical resistivity. The result shows that the 1Hz and 39Hz electromagnetic power spectra are 0. 2 to 1. 4 orders of magnitude higher than the normal values immediately before many earthquakes. The anomalies are represented by the abrupt changes of the electric and magnetic field power spectra in earthquake and aftershock sequences,and the amplitude of change is related to the size of earthquake magnitude and epicentral distance. The electrical resistivity also obviously changes. Therefore, further research on the anomalous characteristics of ELF electromagnetic data will be meaningful to the future use of this instrument in earthquake prediction.
