ABSTRACT
The volcano-magnetic field is most often generated by an overpressure in the magmatic reservoir or by a change of temperature within the volcano. Understanding of the different mechanisms which can generate volcano-magnetic signals has evolved considerably since first observations of the phenomenon. Prior to the 1960s, the single mechanism proposed to explain the observed changes was thermomagnetism. Research on magnetic fields associated with volcanic activity has attempted to explain time variations ranging from seconds to years. To establish if piezomagnetism can account for observed volcano-magnetic signals it is necessary to establish the relationship between induced or remanent magnetization, and both, and the volcanic stress field. Electrokinetic phenomena have their origin in the existence of a double electric layer at the interface between rock and the pore fluid network. Magnetic monitoring of volcanic activity is usually based on the measurement of the field intensity at a number of points on the volcano.
