### Abstract

From the differential geometric theory of the physical interaction field between the deformational field and the magnetic field and thermodynamics principles, we can derive a new non-linear equation on the piezomagnetic effects of plastically deformed rocks without using special knowledge of material properties. Moreover, from von Mises' yield condition (plastic potential), Onsager's theorem (non-linear phenomenological equation) and a new flow rule of the plasticity theory generalized by the theory of the physical interaction field, we lead to a new theoretical relationship between the magnetic susceptibility tensor χ_{mn}^{Pl} on the plastic deformation and the plastic strain tensor ε_{ij}^{Pl} of plastically deformed rocks given by χ_{mn}^{Pl} = 2/3E_{S}ω̃_{mn}^{ij}ε_{ij} ^{Pl} where ω̃_{mn}^{ij} is the fourth-rank asymmetric tensor with a non-linear property on the physical interaction coefficient and E_{S} is the secant modulus referred to plastic strain. Let χ̌_{mn} be an initial magnetic susceptibility tensor, then the second-rank asymmetric tensor (3/2E_{S})χ̌_{mn}ω̃_{ij} ^{mn} is equivalent to Borradaile-Alford's empirical matrix M_{ij} relating strain to susceptibility change. We are developing this relation to infer the strain of plastically deformed rocks from magnetic susceptibility changes.

Original language | English |
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Pages (from-to) | 167-173 |

Number of pages | 7 |

Journal | Physics and Chemistry of the Earth |

Volume | 22 |

Issue number | 1-2 SPEC. ISS. |

DOIs | |

Publication status | Published - 1997 |

### ASJC Scopus subject areas

- Earth and Planetary Sciences(all)