The diurnal variation of the geomagnetic vertical component is exhibited mainly by changes of phase and amplitude before strong earthquakes. Based on data recorded by the network of geomagnetic observatories in China ...The diurnal variation of the geomagnetic vertical component is exhibited mainly by changes of phase and amplitude before strong earthquakes. Based on data recorded by the network of geomagnetic observatories in China for many years, the anomalous features of the appearance time of the minima of diurnal variations （i.e, low-point time） of the geo- magnetic vertical components and the variation of their spatial distribution （i.e, phenomena of low-point displacement） have been studied before the Wenchuan Ms8.0 earthquake. The strong aftershocks after two months＇ quiescence of M6 aftershocks of the Ms8.0 event were forecasted based on these studies. There are good correlativities between these geomagnetic anoma- lies and occurrences of earthquakes. It has been found that most earthquakes occur near the boundary line of sudden changes of the low-point time and generally within four days before or after the 27th or 41st day counting from the day of the appearance of the anomaly. In addition, the imminent anomalies in diurnal-variation amplitudes near the epicentral areas have also been studied before the Wenchuan earthquake.展开更多
Snow cover on the Tibetan Plateau(TP) has been shown to be essential for the East Asian summer monsoon.In this paper, we demonstrate that tropical cyclone(TC) 04B(1999) in the northern Indian Ocean, which made landfal...Snow cover on the Tibetan Plateau(TP) has been shown to be essential for the East Asian summer monsoon.In this paper, we demonstrate that tropical cyclone(TC) 04B(1999) in the northern Indian Ocean, which made landfall during the autumn of 1999, may have contributed to climate anomalies over East Asia during the following spring and summer by increasing snow cover on the TP. Observations indicate that snow cover on the TP increased markedly after TC 04B(1999) made landfall in October of 1999. Sensitivity experiments, in which the TC was removed from a numerical model simulation of the initial field, verified that TC 04B(1999) affected the distribution as well as increased the amount of snow on the TP. In addition, the short-term numerical modeling of the climate over the region showed that the positive snow cover anomaly induced negative surface temperature, negative sensible heat flux, positive latent heat flux, and positive soil temperature anomalies over the central and southern TP during the following spring and summer. These climate anomalies over the TP were associated with positive(negative) summer precipitation anomalies over the Yangtze River valley(along the southeastern coast of China).展开更多
In this paper, the causes of the occurrence of the temperature increase by an impending earthquake of low altitude atmosphere and on the ground surface have been preliminarily expounded through several simulative cont...In this paper, the causes of the occurrence of the temperature increase by an impending earthquake of low altitude atmosphere and on the ground surface have been preliminarily expounded through several simulative controlexperiments. Air polarized by the anomalous atmospheric static electric field is regarded as the primary factor tocreate air temperature increase to a large degree and over a large area in the sunlight. In addition, another causeis considered as the temperature increase effect of “polluted” air.展开更多
Three methods of extracting the information of anomalies of a precursory group are put forward, i.e., the mathematical analyses of the synthetic information of earthquake precursors (S), the inhomogeneous degree of pr...Three methods of extracting the information of anomalies of a precursory group are put forward, i.e., the mathematical analyses of the synthetic information of earthquake precursors (S), the inhomogeneous degree of precursory groups (ID) and the values of short-term and impending anomaly in near-source area (NS). Using these methods, we calculate the observational data of deformation, underground fluid and hydrochemical constituents obtained from different seismic stations in the Sichuan-Yunnan region and conclude that the synthetic precursory anomalies of a single strong earthquake with M S6.0 differ greatly from those of the grouped strong earthquakes, for the anomalous information of precursory groups are more abundant. The three methods of extracting the synthetic precursory anomaly and the related numerical results can be applied into the practice of prediction to the grouped strong earthquakes in the Sichuan-Yunnan region. Inhomogeneous degree (ID) of synthetic precursory anomaly can be identified automatically because it takes the threshold of distributive characteristics of the anomalies of precursory group as its criterion for anomaly.展开更多
This paper gives a report on borehole bulk-strain data recorded at the seismostation Nanton$ in Jiangsu Province from January 1 , 2003 to December 31 , 2008. While the data at Nantong showed much noise possibly due to...This paper gives a report on borehole bulk-strain data recorded at the seismostation Nanton$ in Jiangsu Province from January 1 , 2003 to December 31 , 2008. While the data at Nantong showed much noise possibly due to site instability and no earthquake-related changes, the data at Liuhe showed anomalous changes that began one to several weeks before three earthquakes of magnitude 4.0 to 6.0 at eplcentral distances up to 400 kin.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
The problems in equipment fault detection include data dimension explosion,computational complexity,low detection accuracy,etc.To solve these problems,a device anomaly detection algorithm based on enhanced long short-...The problems in equipment fault detection include data dimension explosion,computational complexity,low detection accuracy,etc.To solve these problems,a device anomaly detection algorithm based on enhanced long short-term memory(LSTM)is proposed.The algorithm first reduces the dimensionality of the device sensor data by principal component analysis(PCA),extracts the strongly correlated variable data among the multidimensional sensor data with the lowest possible information loss,and then uses the enhanced stacked LSTM to predict the extracted temporal data,thus improving the accuracy of anomaly detection.To improve the efficiency of the anomaly detection,a genetic algorithm(GA)is used to adjust the magnitude of the enhancements made by the LSTM model.The validation of the actual data from the pumps shows that the algorithm has significantly improved the recall rate and the detection speed of device anomaly detection,with the recall rate of 97.07%,which indicates that the algorithm is effective and efficient for device anomaly detection in the actual production environment.展开更多
This note mainly discusses the relation of the impending-earthquake satellite thermal infrared anomaly with the ground temperature-increase anomaly, namely, expounds the problem if the satellite thermal infrared anoma...This note mainly discusses the relation of the impending-earthquake satellite thermal infrared anomaly with the ground temperature-increase anomaly, namely, expounds the problem if the satellite thermal infrared anomaly is the reflection of the surficial temperatureincrease anomaly caused by seismic activities on the basis of previous works about the rela-展开更多
According to studies of more than 20 earthquakes with MS≥5.0 in North China, seven features of the short-term and imminent earthquake precursors have been summarized in this paper. At the same time, taking the short-...According to studies of more than 20 earthquakes with MS≥5.0 in North China, seven features of the short-term and imminent earthquake precursors have been summarized in this paper. At the same time, taking the short-term and imminent earthquake stage as the physical process of a source’s medium softening and fault creep, we calculated temporal variation of mean stress, maximum shear stress, body strain, and pore pressure in some certain points (supposed stations) in the source area and its adjacent area by using an anisotropic and nonlinear source model and a finite element method. According to an analysis of these theoretical curves, we conclude that the short-term and imminent earthquake precursors have such characteristics as complex shapes, exponential growth of the precursor number with tune, and precursors’ migration from the outside area to the source area, which to a certain extent reveal the cause of the characteristics of the short-term and imminent earthquake precursor field.展开更多
基金supported by National Key Technologies Research&Development Program of China (Grant No. 2008BAC35B00).
文摘The diurnal variation of the geomagnetic vertical component is exhibited mainly by changes of phase and amplitude before strong earthquakes. Based on data recorded by the network of geomagnetic observatories in China for many years, the anomalous features of the appearance time of the minima of diurnal variations （i.e, low-point time） of the geo- magnetic vertical components and the variation of their spatial distribution （i.e, phenomena of low-point displacement） have been studied before the Wenchuan Ms8.0 earthquake. The strong aftershocks after two months＇ quiescence of M6 aftershocks of the Ms8.0 event were forecasted based on these studies. There are good correlativities between these geomagnetic anoma- lies and occurrences of earthquakes. It has been found that most earthquakes occur near the boundary line of sudden changes of the low-point time and generally within four days before or after the 27th or 41st day counting from the day of the appearance of the anomaly. In addition, the imminent anomalies in diurnal-variation amplitudes near the epicentral areas have also been studied before the Wenchuan earthquake.
基金National Natural Science Foundation of China(4127504841461164006+1 种基金9081502891215302)
文摘Snow cover on the Tibetan Plateau(TP) has been shown to be essential for the East Asian summer monsoon.In this paper, we demonstrate that tropical cyclone(TC) 04B(1999) in the northern Indian Ocean, which made landfall during the autumn of 1999, may have contributed to climate anomalies over East Asia during the following spring and summer by increasing snow cover on the TP. Observations indicate that snow cover on the TP increased markedly after TC 04B(1999) made landfall in October of 1999. Sensitivity experiments, in which the TC was removed from a numerical model simulation of the initial field, verified that TC 04B(1999) affected the distribution as well as increased the amount of snow on the TP. In addition, the short-term numerical modeling of the climate over the region showed that the positive snow cover anomaly induced negative surface temperature, negative sensible heat flux, positive latent heat flux, and positive soil temperature anomalies over the central and southern TP during the following spring and summer. These climate anomalies over the TP were associated with positive(negative) summer precipitation anomalies over the Yangtze River valley(along the southeastern coast of China).
文摘In this paper, the causes of the occurrence of the temperature increase by an impending earthquake of low altitude atmosphere and on the ground surface have been preliminarily expounded through several simulative controlexperiments. Air polarized by the anomalous atmospheric static electric field is regarded as the primary factor tocreate air temperature increase to a large degree and over a large area in the sunlight. In addition, another causeis considered as the temperature increase effect of “polluted” air.
文摘Three methods of extracting the information of anomalies of a precursory group are put forward, i.e., the mathematical analyses of the synthetic information of earthquake precursors (S), the inhomogeneous degree of precursory groups (ID) and the values of short-term and impending anomaly in near-source area (NS). Using these methods, we calculate the observational data of deformation, underground fluid and hydrochemical constituents obtained from different seismic stations in the Sichuan-Yunnan region and conclude that the synthetic precursory anomalies of a single strong earthquake with M S6.0 differ greatly from those of the grouped strong earthquakes, for the anomalous information of precursory groups are more abundant. The three methods of extracting the synthetic precursory anomaly and the related numerical results can be applied into the practice of prediction to the grouped strong earthquakes in the Sichuan-Yunnan region. Inhomogeneous degree (ID) of synthetic precursory anomaly can be identified automatically because it takes the threshold of distributive characteristics of the anomalies of precursory group as its criterion for anomaly.
基金supported by the National Natural Science Foundation of China( 40901272)Social Development Projects of Science and Technology Department of Jiangsu Province(BS2006085)
文摘This paper gives a report on borehole bulk-strain data recorded at the seismostation Nanton$ in Jiangsu Province from January 1 , 2003 to December 31 , 2008. While the data at Nantong showed much noise possibly due to site instability and no earthquake-related changes, the data at Liuhe showed anomalous changes that began one to several weeks before three earthquakes of magnitude 4.0 to 6.0 at eplcentral distances up to 400 kin.
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.
基金National Key R&D Program of China(No.2020YFB1707700)。
文摘The problems in equipment fault detection include data dimension explosion,computational complexity,low detection accuracy,etc.To solve these problems,a device anomaly detection algorithm based on enhanced long short-term memory(LSTM)is proposed.The algorithm first reduces the dimensionality of the device sensor data by principal component analysis(PCA),extracts the strongly correlated variable data among the multidimensional sensor data with the lowest possible information loss,and then uses the enhanced stacked LSTM to predict the extracted temporal data,thus improving the accuracy of anomaly detection.To improve the efficiency of the anomaly detection,a genetic algorithm(GA)is used to adjust the magnitude of the enhancements made by the LSTM model.The validation of the actual data from the pumps shows that the algorithm has significantly improved the recall rate and the detection speed of device anomaly detection,with the recall rate of 97.07%,which indicates that the algorithm is effective and efficient for device anomaly detection in the actual production environment.
基金Project supported by the Seismoscience Joint Foundation
文摘This note mainly discusses the relation of the impending-earthquake satellite thermal infrared anomaly with the ground temperature-increase anomaly, namely, expounds the problem if the satellite thermal infrared anomaly is the reflection of the surficial temperatureincrease anomaly caused by seismic activities on the basis of previous works about the rela-
文摘According to studies of more than 20 earthquakes with MS≥5.0 in North China, seven features of the short-term and imminent earthquake precursors have been summarized in this paper. At the same time, taking the short-term and imminent earthquake stage as the physical process of a source’s medium softening and fault creep, we calculated temporal variation of mean stress, maximum shear stress, body strain, and pore pressure in some certain points (supposed stations) in the source area and its adjacent area by using an anisotropic and nonlinear source model and a finite element method. According to an analysis of these theoretical curves, we conclude that the short-term and imminent earthquake precursors have such characteristics as complex shapes, exponential growth of the precursor number with tune, and precursors’ migration from the outside area to the source area, which to a certain extent reveal the cause of the characteristics of the short-term and imminent earthquake precursor field.
