Magnetic change associated with various mechanical models can be generated from four kinds of sources: i.e. ‘free air’ magnetic change (M1), magnetic terrain effect (M2), effect of source volume change (M3) and piezomagnetic field (M4). For the Mogi model as an example, relative magnitude is compared among these contributions. It is shown that |M4|>>|M2|-|M3|>>|M1|.
