Based on the telluric field data from a Sino-France cooperation station and analysis of the linear characteristic of telluric field polarization, this paper puts forward a new method, called vertical projection to the...Based on the telluric field data from a Sino-France cooperation station and analysis of the linear characteristic of telluric field polarization, this paper puts forward a new method, called vertical projection to the polarization, to recognize seismic electrical anomaly from observation background. Through careful analysis of polarization variation in different time intervals, it is determined that the best time interval for the regression of polarization is 24 h. Telluric observational data from two earthquakes, one is Yongdeng M_s=5.8 earthquake on July 22, 1995, the other is west Tianzhu M_s=5.4 earthquake on June 1, 1996, are processed by this new method, it is interesting to discover that abnormal electrical signals appeared 28 days and respectively. The limit condition of using this method is discussed finally.展开更多
A possible mechanism of earthquake triggering by ionizing radiation of solar flares is considered.A theoretical model and results of numerical calculations of disturbance of electric field,electric current,and heat re...A possible mechanism of earthquake triggering by ionizing radiation of solar flares is considered.A theoretical model and results of numerical calculations of disturbance of electric field,electric current,and heat release in lithosphere associated with variation of ionosphere conductivity caused by absorption of ionizing radiation of solar flares are presented.A generation of geomagnetic field disturbances in a range of seconds/tens of seconds is possible as a result of large-scale perturbation of a conductivity of the bottom part of ionosphere in horizontal direction in the presence of external electric field.Amplitude-time characteristics of the geomagnetic disturbance depend upon a perturbation of integral conductivity of ionosphere.Depending on relation between integral Hall and Pedersen conductivities of disturbed ionosphere the oscillating and aperiodic modes of magnetic disturbances may be observed.For strong perturbations of the ionosphere conductivities amplitude of pulsations may obtain^102 nT.In this case the amplitude of horizontal component of electric field on the Earth surface obtains 0.01 mV/m,electric current density in lithosphere-10-6 A/m2,and the power density of heat release produced by the generated current is 10-7 W/m3.It is shown that the absorption of ionizing radiation of solar flares can result in variations of a density of telluric currents in seismogenic faults comparable with a current density generated in the Earth crust by artificial pulsed power systems(geophysical MHD generator"Pamir・2"and electric pulsed facility"ERGU・600"),which provide regional earthquake triggering and spatiotemporal variation of seismic activity.Therefore,triggering of seismic events is possible not only by man-made pulsed power sources but also by the solar flares.The obtained results may be a physical basis for a novel approach to solve the problem of short・term earthquake prediction based on electromagnetic triggering phenomena.展开更多
Audiomagnetotelluric data were acquired for 10 sounding stations in open fields and roads along the main highways from Campo to Ma’an in Cameroon. An application of the coefficients of anisotropy was used to determin...Audiomagnetotelluric data were acquired for 10 sounding stations in open fields and roads along the main highways from Campo to Ma’an in Cameroon. An application of the coefficients of anisotropy was used to determine the tectonic settings and the nature of the contacts between the sedimentary formation of the Kribi-Campo basin and the cratonic Ntem Complex. The results of this study show that apart from the sedimentary formation, the metamorphic formation in this area comprises two metamorphic blocks: a regional metamorphic block which might be igneous or granitic in nature and composition and seem to be Precambrian and plutonic in origin and a contact or transitional metamorphic block, which might represent schist or gneiss rocks. The contact or transitional metamorphic block might be as a result of a long period of contact between regional metamorphic rocks and rocks of sedimentary formation. These contact/transitional metamorphic rocks which are found sandwiched between rocks of sedimentary formation and rocks of the regional metamorphic block and at varied depths confirm the existence of vertical and sub-vertical contacts between the Kribi-Campo basin and the cratonic Ntem complex. Two types of rock contacts have been identified: a sedimentary-schist contact which is found at the boundary between the sedimentary formation and the transitional metamorphic block and a schist-granite contact between the transitional and regional metamorphic blocks. Two main formations: a sedimentary formation, which is found in the Kribi-Campo sub-basin and the Ntem River bed and its flood plains and the metamorphic formation which includes both the transitional and regional metamorphic rocks have also been identified in the area of study. Subsurface rocks and rock materials have been observed to be highly resistive and occupying almost the entire subsurface in the area of study confirming the high vertical tectonic stability of the Ntem Complex even at contact with the sedimentary Kribi-Campo basin.展开更多
文摘Based on the telluric field data from a Sino-France cooperation station and analysis of the linear characteristic of telluric field polarization, this paper puts forward a new method, called vertical projection to the polarization, to recognize seismic electrical anomaly from observation background. Through careful analysis of polarization variation in different time intervals, it is determined that the best time interval for the regression of polarization is 24 h. Telluric observational data from two earthquakes, one is Yongdeng M_s=5.8 earthquake on July 22, 1995, the other is west Tianzhu M_s=5.4 earthquake on June 1, 1996, are processed by this new method, it is interesting to discover that abnormal electrical signals appeared 28 days and respectively. The limit condition of using this method is discussed finally.
基金funded by RFBR according to the research project No. 18-05-00962
文摘A possible mechanism of earthquake triggering by ionizing radiation of solar flares is considered.A theoretical model and results of numerical calculations of disturbance of electric field,electric current,and heat release in lithosphere associated with variation of ionosphere conductivity caused by absorption of ionizing radiation of solar flares are presented.A generation of geomagnetic field disturbances in a range of seconds/tens of seconds is possible as a result of large-scale perturbation of a conductivity of the bottom part of ionosphere in horizontal direction in the presence of external electric field.Amplitude-time characteristics of the geomagnetic disturbance depend upon a perturbation of integral conductivity of ionosphere.Depending on relation between integral Hall and Pedersen conductivities of disturbed ionosphere the oscillating and aperiodic modes of magnetic disturbances may be observed.For strong perturbations of the ionosphere conductivities amplitude of pulsations may obtain^102 nT.In this case the amplitude of horizontal component of electric field on the Earth surface obtains 0.01 mV/m,electric current density in lithosphere-10-6 A/m2,and the power density of heat release produced by the generated current is 10-7 W/m3.It is shown that the absorption of ionizing radiation of solar flares can result in variations of a density of telluric currents in seismogenic faults comparable with a current density generated in the Earth crust by artificial pulsed power systems(geophysical MHD generator"Pamir・2"and electric pulsed facility"ERGU・600"),which provide regional earthquake triggering and spatiotemporal variation of seismic activity.Therefore,triggering of seismic events is possible not only by man-made pulsed power sources but also by the solar flares.The obtained results may be a physical basis for a novel approach to solve the problem of short・term earthquake prediction based on electromagnetic triggering phenomena.
文摘Audiomagnetotelluric data were acquired for 10 sounding stations in open fields and roads along the main highways from Campo to Ma’an in Cameroon. An application of the coefficients of anisotropy was used to determine the tectonic settings and the nature of the contacts between the sedimentary formation of the Kribi-Campo basin and the cratonic Ntem Complex. The results of this study show that apart from the sedimentary formation, the metamorphic formation in this area comprises two metamorphic blocks: a regional metamorphic block which might be igneous or granitic in nature and composition and seem to be Precambrian and plutonic in origin and a contact or transitional metamorphic block, which might represent schist or gneiss rocks. The contact or transitional metamorphic block might be as a result of a long period of contact between regional metamorphic rocks and rocks of sedimentary formation. These contact/transitional metamorphic rocks which are found sandwiched between rocks of sedimentary formation and rocks of the regional metamorphic block and at varied depths confirm the existence of vertical and sub-vertical contacts between the Kribi-Campo basin and the cratonic Ntem complex. Two types of rock contacts have been identified: a sedimentary-schist contact which is found at the boundary between the sedimentary formation and the transitional metamorphic block and a schist-granite contact between the transitional and regional metamorphic blocks. Two main formations: a sedimentary formation, which is found in the Kribi-Campo sub-basin and the Ntem River bed and its flood plains and the metamorphic formation which includes both the transitional and regional metamorphic rocks have also been identified in the area of study. Subsurface rocks and rock materials have been observed to be highly resistive and occupying almost the entire subsurface in the area of study confirming the high vertical tectonic stability of the Ntem Complex even at contact with the sedimentary Kribi-Campo basin.
