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Investigating Active Faults in New Zealand Using High-resolution Seismic Reflection and Ground Penetrating Radar Methods
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, Near Surface 2009 - 15th EAGE European Meeting of Environmental and Engineering Geophysics, Sep 2009, cp-134-00044
- ISBN: 978-90-73781-72-6
Abstract
An understanding of the characteristics of fault zones which produce infrequent large earthquakes is essential for seismic hazard and risk assessment. In an attempt to supplement palaeoseismic methods and determine the structure of active faults in the deeper subsurface, we have acquired and processed ground-penetrating radar (GPR) data (up to 20m depth) and high-resolution seismic reflection data (several hundred metres to 1km depth) across three major fault systems located on the South Island of New Zealand. The seismic and GPR data are subjected to a wide variety of processing schemes, generating clear and vivid images of all target structures. The Alpine Fault is constrained to be steeply dipping, with a ~35 m vertical offset of the late Pleistocene erosional basement surface. The Canterbury Plains data show that basement and Cretaceous-Tertiary layers have been intensely thrust faulted and folded, and in addition, display evidence of gentle folding and disruption in some of the overlying Quaternary layers. The Ostler Fault Zone data show a main fault strand dipping at ~50°, with significant off-fault subsidiary faulting and folding and strong lateral variation along strike.