*Earth Planets Space,* Vol. 61 (No. 10), pp. 1163-1168, 2009

## Calculation of the piezomagnetic field arising from uniform regional stress in inhomogeneously magnetized crust

Ken'ichi Yamazaki

Disaster Prevention Research Institute, Kyoto University, Gokasyo, Uji, Kyoto 611-0011, Japan

(Received January 21, 2009; Revised May 22, 2009; Accepted June 28, 2009; Online published November 30, 2009)

**Abstract: **
This paper describes a simple procedure for the calculation of the piezomagnetic field arising from uniform regional stress in heterogeneously magnetized crust. There exists a strong similarity between the spatial distributions of anomalies in the geomagnetic total force values arising from magnetization structures in the Earth's crust and those arising from piezomagnetic signals that arise from there. This similarity enables us to compute the piezomagnetic field due to uniform regional stress without the need to determine the explicit structure of magnetization intensities in the crust. This situation is similar to that of "reduction to the pole", which is commonly used to interpret magnetic survey data. An explicit formula is presented that gives the 2-D spectrum of the piezomagnetic field from that of local magnetic anomalies; the formula is then applied to synthetic data. Calculated values are compared with the exact solution of the piezomagnetic field in order to assess the efficacy of the proposed method. The comparison verifies that calculations performed using the formula yield sufficiently accurate values for practical use.

**Key words: **
Piezomagnetic effect, regional stress, magnetic anomaly, reduction to the pole.

Corresponding author E-mail: kenichi@eqh.dpri.kyoto-u.ac.jp

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