A MAGNETOTELLURIC STUDY OF THE ALPINE FAULT, NEW-ZEALAND

Magnetotelluric soundings have been made at seven locations on a 4 km profile crossing the Alpine Fault in the South Island of New Zealand. The 'distortion' techniques of Groom & Bailey (1989) and Lilley (1998 a,b) have been used to derive regional apparent resistivity and phase curves that correspond to electromagnetic induction in orientations pa rallel and perpendicular to the fault. 2-D inversion of the regional r esponses reveals that a narrow (<1 km wide) conductive zone is associa ted with the Alpine Fault. This conductor is most probably related to the heating of deep circulating meteoric water in a region in which en hanced temperatures occur at shallow depth due to the tectonic uplift of the Southern Alps.