Magnetism of Rocks and Volumetric Strain in Uniaxial Failure Tests

Martin, R. F.; Wyss, Max

doi:10.1007/978-3-0348-5534-1_5

Cited by 7 publications

(6 citation statements)

References 12 publications

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“…A memory effect in remnant magnetisation was observed [95]. Cyclic uniaxial compression tests were performed on gabbro specimens whereby the intensity of remnant magnetisation was measured in the direction parallel to the loading axis.…”

Section: Stress (Strain) Memory Effects In Rocksmentioning

confidence: 99%

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Fracture‐induced Physical Phenomena and Memory Effects in Rocks: A Review

Lavrov

2005

Strain

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Losing stability, the earth split; Losing strength, the mountains sank. Tao De Ching Abstract: Fracture‐induced physical phenomena allow a real‐time monitoring of damage evolution in rocks induced by mechanical loading. Some of these phenomena, e.g. plastic deformation, changes in permeability and electric resistivity, provide an overall estimate of damage as a function of stress. Others, such as acoustic emission or electromagnetic emission, allow an exact location of cracks in space and time. Being nondestructive, monitoring techniques based on fracture‐induced physical phenomena, are a basis for prediction of earthquakes and rockbursts in underground mines. They are also crucial for a fundamental understanding of rock fracture mechanisms and for developing constitutive models of rock behaviour. Memory effects take place in rocks subjected to cyclic loading with the peak stress (strain) value increasing from cycle to cycle. The effects are represented by certain characteristic changes in rock properties and parameters that are observed when the stress (strain) reaches its previous peak value. Potential applications of memory effects range from stress measurement techniques to earthquake prediction to damage surface scanning. Essential experimental and theoretical results on fracture‐induced physical phenomena and memory effects in rocks are considered in the article. Possible applications as well as not‐yet‐clear points are discussed.

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Section: Stress (Strain) Memory Effects In Rocksmentioning

confidence: 99%

“…Magnetisation is measured in the direction parallel to the loading axis; based on Ref. [95] performed on coal specimens, permeability being measured along the r 1 -axis [96]. Loading was either hydrostatic or triaxial proportional, i.e.…”

Section: Intensity Of Magnetizationmentioning

confidence: 99%

Fracture‐induced Physical Phenomena and Memory Effects in Rocks: A Review

Lavrov

2005

Strain

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“…Much experimental work has been carried out on the stress sensitivities of both the magnetic susceptibility and remanent magnetization [Nagata, 1970a, b;Martin and Wyss, 1975;Wyss and Martin, 1977]. The general result is that rocks change their magnetization as a function of stress.…”

Section: Piezomagnetismmentioning

confidence: 99%

Electromagnetic precursors to earthquakes in the Ulf band: A review of observations and mechanisms

Park¹,

Johnston²,

Madden³

et al. 1993

Reviews of Geophysics

219

118

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Despite over 2 decades of international and national monitoring of electrical signals with the hope of detecting precursors to earthquakes, the scientific community is no closer to understanding why precursors are observed only in some cases. Laboratory measurements have demonstrated conclusively that self potentials develop owing to fluid flow and that both resistivity and magnetization change when rocks are stressed. However, field experiments have had much less success. Many purported observations of low‐frequency electrical precursors are much larger than expectations based on laboratory results. In some cases, no precursors occurred prior to earthquakes, or precursory signals were reported with no corresponding coseismic signals. Nonetheless, the field experiments are in approximate agreement with laboratory measurements. Maximum resistivity changes of a few percent have been observed prior to some earthquakes in China, but the mechanism causing those changes is still unknown. Anomalous electric and magnetic fields associated with fluid flow prior to earthquakes may have been observed. Finally, piezomagnetic signals associated with stress release in earthquakes have been documented in measurements of magnetic fields.

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“…The possibility that observable magnetic field variations are associated with tectonic stress accumulation presents a possible means of predicting earthquakes by monitoring magnetic field changes. This intriguing idea is supported by laboratory observations of changes in magnetic properties of rock in response to stress changes [Kalashnikov, 1954;Kapitsa, 1955;Ohnaka and Kinoshita, 1968;Martin and Wyss, 1975;Martin et al, 1978]. Assuming stress induced susceptibility or remanence changes, theoretical calculations indicate that magnetic field changes as large as a few gammas (nT) are expected to be associated with tectonic stress changes [Shamsi and Stacey, 1969;Talwani and Kovach, 1972].…”

Section: Introductionmentioning

confidence: 91%

Theory of electrokinetic‐magnetic anomalies in a faulted half‐space

Fitterman¹

1979

J. Geophys. Res.

138

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Fluid motion in the vicinity of a vertical fault separating regions of different streaming potential coefficient can produce an external magnetic field of observable magnitude. If tectonic stress changes along the fault produce fluid motion, the magnetic field changes would be indicative of stress changes, and might precede severe fault motion. The largest component of the magnetic field is oriented parallel to the strike of the fault. Magnetic field changes produced by this mechanism will have electric fields associated with them with similar time variation; this is in contrast to magnetic field changes produced by changes in susceptibility or remanent magnetization, which have no associated electric field. Experiments aimed at the detection of tectonomagnetic effects should include electric field sensors to help in determining the source of any observed variations. The hypothesis of Mizutani and Ishido (1976) that the magnetic field changes associated with the Matsushiro earthquake swarms were produced by electrokinetic currents seems reasonable.1.

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Magnetism of Rocks and Volumetric Strain in Uniaxial Failure Tests

Cited by 7 publications

References 12 publications

Fracture‐induced Physical Phenomena and Memory Effects in Rocks: A Review

Fracture‐induced Physical Phenomena and Memory Effects in Rocks: A Review

Electromagnetic precursors to earthquakes in the Ulf band: A review of observations and mechanisms

Theory of electrokinetic‐magnetic anomalies in a faulted half‐space

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