High-frequency seismo-electromagnetic effects
TL;DR: A review of the high-frequency seismo-electromagnetic phenomena already observed, and occurring before, as well as after, the great Alaskan earthquake in 1964 can be found in this paper.
About: This article is published in Physics of the Earth and Planetary Interiors.The article was published on 1993-04-01. It has received 121 citations till now.
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TL;DR: In this paper, magnetic, electric and electromagnetic field variations were obtained on Mt. Unzen in Japan, Reunion Island in Indian Ocean, the Long Valley volcanic caldera in California, and for faults in China and Russia, California and several other locations.
Abstract: New observations of magnetic, electric and electromagnetic field variations, possibly related to recent volcanic and seismic events, have been obtained on Mt. Unzen in Japan, Reunion Island in Indian Ocean, the Long Valley volcanic caldera in California, and for faults in China and Russia, California and several other locations. For volcanic events, contributions from different physical processes can be identified during the various eruption stages. Slow processes (weeks to months) include near-surface thermal demagnetization effects, piezomagnetic effects, and effects from rotation/displacement of magnetized material. Rapid processes (seconds to days) include piezomagnetic effects from instantaneous stress redistribution with explosive eruptions and electrokinetic effects from rupture of high pressure fluid compartments commonly encountered in volcanic regions. For seismic events, the observed coseismic offsets are instantaneous, provided care has been taken to ensure sensors are insensitive to seismic shaking and are in regions of low magnetic field gradient. Simple piezomagnetic dislocation models based on geodetically and seismically determined fault parameters generally match the observed signals in size and sign. Electrokinetic effects resulting from rupture of fluid filled compartments at hydrostatic to lithostatic pore pressures can generate transient signals in the frequency band 100 Hz to 0.01 Hz. However, large-scale fluid driven processes are not evident in near-field measurements in the epicentral region minutes to weeks before large earthquakes. The subset of ionospheric disturbances generated by trapped atmospheric pressure waves (also termed gravity waves and/or acoustic waves, traveling ionospheric disturbances or TID's) that are excited by earthquakes and volcanic eruptions are common and propagate to great distances. These are known and expected consequences of earthquakes, volcanic explosions (and other atmospheric disturbances), that must be identified and their effects removed from VLF/ULF electromagnetic field records before associating new observations of ionospheric disturbances with earthquake activity.
288 citations
Cites background from "High-frequency seismo-electromagnet..."
...Such emissions have been reported detected at great distances from these earthquakes (Gokhberg et al., 1982; Oike and Ogawa, 1982; Yoshino et al., 1985; Yoshino, 1991; Parrot et al., 1993; Fujinawa and Takahashi, 1994; Hayakawa and Fujinawa, 1994) and are reported detected also in satellite data (Molchanov et al....
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...…been reported detected at great distances from these earthquakes (Gokhberg et al., 1982; Oike and Ogawa, 1982; Yoshino et al., 1985; Yoshino, 1991; Parrot et al., 1993; Fujinawa and Takahashi, 1994; Hayakawa and Fujinawa, 1994) and are reported detected also in satellite data (Molchanov et al.,…...
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TL;DR: A review of developments in ELF and VLF radio-wave propagation research over the last 50 years of the Journal of Atmospheric and Solar-Terrestrial Physics can be found in this paper.
251 citations
Cites background from "High-frequency seismo-electromagnet..."
...Perturbation of VLF waves by earthquakes Perturbations in VLF phase and amplitude have been reported to occur before large earthquakes (Hayakawa and Fujinawa, 1994; Parrot et al., 1993; Parrot, 1995)....
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TL;DR: In this paper, a physical model was developed to bridge the traditional precursors of earthquakes and ionospheric ones, demonstrating that the latter belong to the same family, and a possible system of ground-based measurements and satellite monitoring was proposed for regional and global monitoring and possible short-term prediction of destructive earthquakes.
Abstract: This paper accumulates the recent advances in scientific understanding of the problem of seismo-ionospheric coupling. Present research focuses on three main areas: the physical mechanism, main phenomenological features of ionospheric variations associated with earthquakes, and their statistical properties permitting use of them in practical applications. In this paper, the developed physical model bridges the traditional precursors of earthquakes and ionospheric ones, demonstrating that the latter belong to the same family. In this regard the earthquake preparation zone is key generating the scaling law and the relationship between geochemical precursors, anomalous electric field involved in ionospheric variations initiated, and the ionospheric irregularities themselves. Revealed ionospheric precursor phenomena and their statistical parameters are used to develop a pattern recognition technique and other statistical processing techniques that can be used in short-term earthquake prediction. Finally a possible system of ground based measurements and satellite monitoring is proposed for regional and global monitoring and possible short-term prediction of destructive earthquakes.
215 citations
Cites background from "High-frequency seismo-electromagnet..."
...(Key words: Ionospheric precursors)...
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...This long history of seismo-ionospheric coupling studies can be found in the following reviews: Liperovsky et al. (1990); Gaivoronskaya (1991); Liperovsky et al. (1992); Parrot et al. (1993); Pulinets et al. (1994); Gokhberg et al. (1995)....
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TL;DR: In this article, the feasibility of the charge separation model as the source of electromagnetic radiation received from the fracture of brittle materials is demonstrated, and an analytical expression and a finite difference method enable the calculation of currents flowing around the tip of a crack.
155 citations
TL;DR: In this paper, the authors formulated a coupling model for the stressed rock-Earth surface charges-atmosphere ionosphere system, where the stressed-rock acts as the dynamo to provide the currents for the coupling system.
Abstract: [1] Recent ionospheric observations indicate that the total electron content (TEC) may anomalously decrease or increase up to 5–20% before the occurrence of big earthquakes. The ionospheric density variations can be caused by earth surface charges/currents produced from electric currents associated with the stressed rock. We formulate a coupling model for the stressed rock-Earth surface charges-atmosphere-ionosphere system. The stressed-rock acts as the dynamo to provide the currents for the coupling system. The electric fields and currents in the atmosphere and the lower boundary of ionosphere are obtained by solving the current continuity equation, ∇ • J = 0, where J is the current density. A three-dimensional ionosphere simulation code is then used to study the ionospheric dynamics based on the obtained electric fields and currents. The simulation results show that a current density Jrock = 0.2–10 μA/m2 in an earthquake fault zone is required to cause daytime TEC variations of 2–25%. The simulation results also show that a current density Jrock = 0.01–1 μA/m2 can lead to nighttime TEC variations of 1–30% as well as the formation of a nighttime plasma bubble (equatorial spread F) extending over the whole magnetic flux tube containing the earthquake epicenter. We suggest that observations of daytime and nighttime TEC variations and a nighttime plasma bubble within the affected region can be used as precursors for earthquake prediction.
154 citations
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TL;DR: In this article, an approximate solution of the problem for a soft elastic inclusion in an elastic half-space is presented. But the authors assume that the moduli of the inclusion differ slightly from those of the surrounding medium (by no more than 30%).
Abstract: During the earthquake preparation a zone of cracked rocks is formed in the region of a future earthquake focal zone under the influence of tectonic stresses. In the study of the surrounding medium this region may be considered as a solid inclusion with altered moduli. The inclusion appearance causes a redistribution of the stresses accompanied by corresponding deformations. This paper deals with the study of deformations at the Earth's surface, resulting from the appearance of a soft inclusion. The Appendix contains an approximate solution of the problem for a soft elastic inclusion in an elastic half-space. It is assumed that the moduli of the inclusion differ slightly from those of the surrounding medium (by no more than 30%). The solution permits us to calculate the deformations at the Earth's surface for the inclusion with an arbitrary heterogeneity and anisotropy. The problem is solved by the small perturbation method. The calculation is made for a special case of a homogeneous isotropic inclusion where only the shear modulus decreases. The shear stresses act at infinity. The equations are deduced for the estimation of deformations and tilts at the Earth's surface as a function of the magnitude of the preparing earthquake and the distance from the epicentre. Comparison has shown a satisfactory agreement between the theoretical and field results. Let us assume that the zone of effective manifestation of the precursor deformations is a circle with the centre in the epicentre of the preparing earthquake. The radius of this circle called ‘strain radius’ may be calculated from the equation
$$\rho = 10^{0.43M} km,$$
where M is the magnitude. It was shown that the precursors of other physical nature fall into this circle.
908 citations
TL;DR: In this paper, the authors report the results of measurements of low frequency magnetic noise by two independent monitoring systems prior to the occurrence of the M{sub s} 7.1 Loma Prieta earthquake of 17 October 1989.
Abstract: The authors report the results of measurements of low frequency magnetic noise by two independent monitoring systems prior to the occurrence of the M{sub s} 7.1 Loma Prieta earthquake of 17 October 1989. Their measurements cover 25 narrow frequency bands in the more than six-decade frequency range 0.01 Hz-32 kHz, with a time resolution varying from a half hour in the ULF range (0.01-10 Hz) to one second in the ELF/VLF range (10 Hz-32 kHz). The ULF system is located near Corralitos, about 7 km from the epicenter. The ELF/VLF system is located on the Stanford campus, about 52 km from the epicenter. Analysis of the ELF/VLF system is located on the Stanford campus, about 52 km from the epicenter. Analysis of the ELF/VLF data has revealed no precursor activity that they can identify at this time. However, the ULF data have some distinctive and anomalous features. First, a narrow-band signal appeared in the range 0.05-0.2 Hz around September 12 and persisted until the appearance of the second anomalous feature, which consisted of a substantial increase in the noise background starting on 5 October and covering almost the entire frequency range of the ULF system. Third, there was an anomalousmore » dip in the noise background in the range 0.2-5 Hz, starting one day ahead of the earthquake. Finally, and perhaps most compelling, there was an increase to an exceptionally high level of activity in the range 0.01-0.5 Hz starting approximately three hours before the earthquake. There do not appear to have been any magnetic field fluctuations originating in the upper atmosphere that can account for this increase. Further, while the systems are sensitive to motion, seismic measurements indicate that there were no significant shocks preceding the quake. Thus, the various anomalous features in the data, and in particular the large-amplitude increase in activity starting three hours before the quake, may have been magnetic precursors.« less
601 citations
TL;DR: In this article, the physical properties of the preseismic transient variations in the electrotelluric field were described and a few points that were not properly emphasized in previous publications were clarified.
486 citations
TL;DR: In this article, the authors reviewed the latest developments in seismic electric signals (SES) based earthquake prediction and described the current procedures used to predict the epicenter and magnitude of an impending earthquake.
394 citations
TL;DR: The theoretical and observational evidence concerning the global propagation of atmospheric gravity waves is reviewed in this article, with special emphasis on the waves generated in the auroral zones, and it is concluded that the only natural sources of large-scale TIDs are in the ionospheric zones.
392 citations