Subsurface structure of the Canterbury region interpreted from gravity and aeromagnetic data

Abstract The interpretation of gravity and magnetic data acquired over the Christchurch region reveals distinct sets of lineaments postulated to be associated with basement structure. Two sets of lineaments are identified with NNE and broadly E–W orientations. Both sets of lineaments may relate to faults that formed in Cretaceous time and which have been reactivated in the late Cenozoic. There appears to be a boundary between separate crustal domains in the Rolleston area. The Rolleston–Lyttelton Volcano domain is characterised by three E–W lineaments which are segmented on a 2–4 km length scale. West of Rolleston, lineaments are typically segmented at 5 km or more. There is a good correlation between recent seismicity and the middle lineament east of Rolleston, indicating that interpretation of gravity and magnetic anomaly data may provide useful information on the location of future seismic activity.