38 Electromagnetic fields generated by earthquakes

Johnston, M. J. S.

doi:10.1016/s0074-6142(02)80241-8

Cited by 16 publications

(18 citation statements)

References 112 publications

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“…Crustal deformation and earthquake (EQ)‐related fault failure processes are accompanied with electric and magnetic fields generation mechanisms [ Johnston , ]. According to Johnston [], a careful work still needs to be done to convincingly demonstrate causality between “precursory” electric and magnetic fields signals and earthquakes and consistency with complementary geophysical data as the state of stress, strain, material properties, fluid content, and approach to failure of the Earth's crust in seismically active regions.…”

Section: Introductionmentioning

confidence: 99%

Experimental evidence of electrification processes during the 2009 L'Aquila earthquake main shock

Nenovski

2015

Geophysical Research Letters

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Two types of coseismic magnetic field events are simultaneously observed: transient offset events and magnetic field signal that occurred at the destructive, M w 6.1 L'Aquila earthquake main shock. The offset event, conventionally interpreted as a signature of piezomagnetic effects, however, could not be explained as such. In the second type of coseismic event, the transient magnetic signal starts simultaneously with the offset event and reaches amplitude of 0.8 nT in the total magnetic field. The signal is a local one; its amplitude shape resembles diffusion-like form with time scale characteristics that are indicative for a source deep in the crust. The polarity of the transient signal is in the horizontal plane and nearly parallel to the L'Aquila fault strike. NENOVSKI EVIDENCE OF ELECTRIFICATION PROCESSES 7476

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Section: Introductionmentioning

confidence: 99%

Experimental evidence of electrification processes during the 2009 L'Aquila earthquake main shock

Nenovski

2015

Geophysical Research Letters

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“…The earthquakes affect the electrodynamics of the atmosphere through the generation of electric and magnetic fields with crustal deformation, fault-failure-related piezomagnetism, stress/conductivity, electrokinetic effects, charge generation processes, thermal remagnetization, and demagnetization effects, and so forth [67]. These processes in the Earth's lithosphere relate with disturbances in the atmosphere and ionosphere.…”

Section: Physics Of Earth's Atmosphere-ionosphere (Ai) Couplingmentioning

confidence: 99%

Electrodynamical Coupling of Earth's Atmosphere and Ionosphere: An Overview

Singh

Siingh

Singh

et al. 2011

International Journal of Geophysics

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Electrical processes occurring in the atmosphere couple the atmosphere and ionosphere, because both DC and AC effects operate at the speed of light. The electrostatic and electromagnetic field changes in global electric circuit arise from thunderstorm, lightning discharges, and optical emissions in the mesosphere. The precipitation of magnetospheric electrons affects higher latitudes. The radioactive elements emitted during the earthquakes affect electron density and conductivity in the lower atmosphere. In the present paper, we have briefly reviewed our present understanding of how these events play a key role in energy transfer from the lower atmosphere to the ionosphere, which ultimately results in the Earth's atmosphere-ionosphere coupling.

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“…An unanticipated observation of this study is the apparent sensitivity of this sensor to electromagnetic (EM) signals generated during dynamic stick-slip along the 2-m fault used in these tests. While clear EM signals have long been observed nearby, and at the time of many large earthquakes and volcanic eruptions apparently related to crustal stress release, no unambiguous observations of EM precursor behavior in the epicentral region have been observed [ 21 , 22 , 23 , 24 ]. Some associations of global EM disturbances in the ionosphere and magnetosphere prior to large earthquakes have been made [ 25 ], but these observations appear to result from inadequate correction of normal EM disturbances and selective use of data only prior to these earthquakes [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ].…”

Section: Introductionmentioning

confidence: 99%

“…EM effects can be both fast and slow since movement of the crust can occur fast (earthquakes) and slowly (tectonic loading). Triboelectric effects result from charge separation during microcracking and rock shearing around the rupture surface [ 23 ]. Regardless of the origin of the signals detected in this report, which are not known, the study of the origin and quantification of suspected EM signals observed in these tests requires equipment and techniques beyond the scope of this report.…”

Section: Introductionmentioning

confidence: 99%

A Wideband Magnetoresistive Sensor for Monitoring Dynamic Fault Slip in Laboratory Fault Friction Experiments

Kilgore

2017

Sensors

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A non-contact, wideband method of sensing dynamic fault slip in laboratory geophysical experiments employs an inexpensive magnetoresistive sensor, a small neodymium rare earth magnet, and user built application-specific wideband signal conditioning. The magnetoresistive sensor generates a voltage proportional to the changing angles of magnetic flux lines, generated by differential motion or rotation of the near-by magnet, through the sensor. The performance of an array of these sensors compares favorably to other conventional position sensing methods employed at multiple locations along a 2 m long × 0.4 m deep laboratory strike-slip fault. For these magnetoresistive sensors, the lack of resonance signals commonly encountered with cantilever-type position sensor mounting, the wide band response (DC to ≈ 100 kHz) that exceeds the capabilities of many traditional position sensors, and the small space required on the sample, make them attractive options for capturing high speed fault slip measurements in these laboratory experiments. An unanticipated observation of this study is the apparent sensitivity of this sensor to high frequency electomagnetic signals associated with fault rupture and (or) rupture propagation, which may offer new insights into the physics of earthquake faulting.

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38 Electromagnetic fields generated by earthquakes

Cited by 16 publications

References 112 publications

Experimental evidence of electrification processes during the 2009 L'Aquila earthquake main shock

Experimental evidence of electrification processes during the 2009 L'Aquila earthquake main shock

Electrodynamical Coupling of Earth's Atmosphere and Ionosphere: An Overview

A Wideband Magnetoresistive Sensor for Monitoring Dynamic Fault Slip in Laboratory Fault Friction Experiments

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