Four ULF (0.01 Hz - 20 Hz) electromagnetic stations had been gradually established and put into service from 2010 to 2011 in Zhaotong area, Yunnan province. Two stations of Qiaojia and Yongshan have been running with ...Four ULF (0.01 Hz - 20 Hz) electromagnetic stations had been gradually established and put into service from 2010 to 2011 in Zhaotong area, Yunnan province. Two stations of Qiaojia and Yongshan have been running with continuous and high quality recordings and free of influence of solar activities, like magnetic storms. In this investigation, daily recordings from 1 January 2020 to 22 May 2021 have been examined of these both stations. The results show that weak anomalous signals appeared at the beginning of March 2021 with relative low magnitudes of 0.6 nT at Qiaojia station and 0.3 nT at Yongshan station. At the end of this month, the emissions gained an abrupt increase and the amplitudes reached up to 3.8 nT at Qiaojia station and 1.2 nT at Yongsha station. Then, the amplitude decreased to be 0.5 - 1.5 nT and 0.6 - 1.3 nT respectively at both stations but with a high variation frequency in all components. This situation lasted till the Yangbi </span><i><span style="font-family:Verdana;">M</span></i><sub><span style="font-family:Verdana;">S</span></sub><span style="font-family:Verdana;"> 6.4 earthquake happened on May 21, 2021, more than 300 km away from these two ULF observing stations. Totally, the ULF magnetic emissions had been characterized by a synchronous variation in all components at two observing stations.展开更多
The Kumamoto area of Kyusyu Island was attacked by a series of large earthquakes (EQs) in April, 2016. The first two foreshocks had the magnitudes of 6.5 and 6.4, and about 1 day later there was the main shock on 15 A...The Kumamoto area of Kyusyu Island was attacked by a series of large earthquakes (EQs) in April, 2016. The first two foreshocks had the magnitudes of 6.5 and 6.4, and about 1 day later there was the main shock on 15 April (UT) with magnitude 7.3. These are fault-type EQs, and so we would expect a variety of electromagnetic precursors to these EQs because we had detected different phenomena for the 1995 Kobe EQ, same fault-type EQ. As for the lithospheric effect, the ULF data at Kanoya observatory (about 150 km from the EQ epicenters) are used, but the simple statistical analysis could not provide us with any clear evidence of ULF radiation from the lithosphere. However, our conventional analyses indicated clear signatures in the atmosphere as ULF/ELF impulsive emissions and also in the ionosphere as observed by means of VLF propagation anomalies and ULF depression. ULF/ELF radiation appeared on 8-11 April (in UT) (maximum on 10 and 11 April (UT)), while ULF depression took place on 8 and 10 April (in UT), so that both atmospheric radiation and ionospheric perturbation took place nearly during the same time period.展开更多
This work is an attempt to critically analyze the existing theoretical models of the impact of earthquake preparation processes on the state of the earth’s atmosphere and ionosphere in the zone of growing seismic act...This work is an attempt to critically analyze the existing theoretical models of the impact of earthquake preparation processes on the state of the earth’s atmosphere and ionosphere in the zone of growing seismic activity, as well as the mechanisms of formation and transfer of disturbances in various media over the earthquake center. The determining factor (criterion) of the analysis is the degree of compliance of the simulation results with experimental data obtained at various phases of earthquake development by direct and remote diagnostic methods using ground and aerospace technologies. The key role is played by the model’s compliance with the results of measuring electric fields and currents in the near-ground atmosphere and ionosphere, small-scale ionospheric inhomogeneities and correlated field-aligned currents and electromagnetic ULF/ELF emissions. A full-fledged model should also explain the origin of such seismic related phenomena as the generation in the troposphere and over-horizon propagation of pulsed VHF radiation, thermal effects and associated IR emissions as well as the modification of plasma distribution in the D, E and F layers of the ionosphere. The use of this criterion in the analysis allowed us to identify a theoretical model that most fully describes the totality of the above-mentioned experimental data within a single physical mechanism. This is an electrodynamic model based on the perturbation of the conductivity current in the global atmosphere—ionosphere electric circuit due to the injection of charged aerosols into the atmosphere during the preparation and development of an earthquake. The present paper describes this model and the formation mechanisms of related phenomena in the atmosphere and ionosphere, which can be considered as short-term precursors to earthquakes.展开更多
文摘Four ULF (0.01 Hz - 20 Hz) electromagnetic stations had been gradually established and put into service from 2010 to 2011 in Zhaotong area, Yunnan province. Two stations of Qiaojia and Yongshan have been running with continuous and high quality recordings and free of influence of solar activities, like magnetic storms. In this investigation, daily recordings from 1 January 2020 to 22 May 2021 have been examined of these both stations. The results show that weak anomalous signals appeared at the beginning of March 2021 with relative low magnitudes of 0.6 nT at Qiaojia station and 0.3 nT at Yongshan station. At the end of this month, the emissions gained an abrupt increase and the amplitudes reached up to 3.8 nT at Qiaojia station and 1.2 nT at Yongsha station. Then, the amplitude decreased to be 0.5 - 1.5 nT and 0.6 - 1.3 nT respectively at both stations but with a high variation frequency in all components. This situation lasted till the Yangbi </span><i><span style="font-family:Verdana;">M</span></i><sub><span style="font-family:Verdana;">S</span></sub><span style="font-family:Verdana;"> 6.4 earthquake happened on May 21, 2021, more than 300 km away from these two ULF observing stations. Totally, the ULF magnetic emissions had been characterized by a synchronous variation in all components at two observing stations.
文摘The Kumamoto area of Kyusyu Island was attacked by a series of large earthquakes (EQs) in April, 2016. The first two foreshocks had the magnitudes of 6.5 and 6.4, and about 1 day later there was the main shock on 15 April (UT) with magnitude 7.3. These are fault-type EQs, and so we would expect a variety of electromagnetic precursors to these EQs because we had detected different phenomena for the 1995 Kobe EQ, same fault-type EQ. As for the lithospheric effect, the ULF data at Kanoya observatory (about 150 km from the EQ epicenters) are used, but the simple statistical analysis could not provide us with any clear evidence of ULF radiation from the lithosphere. However, our conventional analyses indicated clear signatures in the atmosphere as ULF/ELF impulsive emissions and also in the ionosphere as observed by means of VLF propagation anomalies and ULF depression. ULF/ELF radiation appeared on 8-11 April (in UT) (maximum on 10 and 11 April (UT)), while ULF depression took place on 8 and 10 April (in UT), so that both atmospheric radiation and ionospheric perturbation took place nearly during the same time period.
文摘This work is an attempt to critically analyze the existing theoretical models of the impact of earthquake preparation processes on the state of the earth’s atmosphere and ionosphere in the zone of growing seismic activity, as well as the mechanisms of formation and transfer of disturbances in various media over the earthquake center. The determining factor (criterion) of the analysis is the degree of compliance of the simulation results with experimental data obtained at various phases of earthquake development by direct and remote diagnostic methods using ground and aerospace technologies. The key role is played by the model’s compliance with the results of measuring electric fields and currents in the near-ground atmosphere and ionosphere, small-scale ionospheric inhomogeneities and correlated field-aligned currents and electromagnetic ULF/ELF emissions. A full-fledged model should also explain the origin of such seismic related phenomena as the generation in the troposphere and over-horizon propagation of pulsed VHF radiation, thermal effects and associated IR emissions as well as the modification of plasma distribution in the D, E and F layers of the ionosphere. The use of this criterion in the analysis allowed us to identify a theoretical model that most fully describes the totality of the above-mentioned experimental data within a single physical mechanism. This is an electrodynamic model based on the perturbation of the conductivity current in the global atmosphere—ionosphere electric circuit due to the injection of charged aerosols into the atmosphere during the preparation and development of an earthquake. The present paper describes this model and the formation mechanisms of related phenomena in the atmosphere and ionosphere, which can be considered as short-term precursors to earthquakes.
