A seismic study of active faults, Canterbury, New Zealand

Abstract

The 2010-2011 Canterbury earthquake sequence on the South Island of New Zealand occurred in a region where hidden faults systems were unknown, but were suspected. Following the 2011 Christchurch earthquake, 2D seismic reflection data was acquired in the Canterbury region. The seismic data, along with a regional tectonic and geologic overview, is used to image, interpret, and identify faults extending to basement structure beneath the Canterbury Plains. Seismic risk hazard is further assessed through the multi-channel analysis of surface waves (MASW) method, where Rayleigh wave dispersion curves are inverted to generate shear wave velocity profiles. Low shear velocity areas are identified, indicating lower soil stiffness and thus risk of potential liquefaction which is an important characterization in seismically active areas. Further fault zone research is investigated by seismic physical modeling inspired by the Greendale Fault in New Zealand, and final imaged results are comparable to acquired field data.