Abstract - The recent earthquakes in Christchurch, New Zealand, show that active faults, capable of generating large-magnitude earthquakes, can be hidden beneath the Earth’s surface. Combining near-surface paleoseismic data with deep onshore seismic-reflection lines, we identify sub-resolution active faults and examine fault growth on different timescales in the Taranaki Rift, New Zealand. Displacement rates vary temporally on individual faults by in excess of an order of magnitude over timescales of thousands to millions of years, changes which are attributed to fault interactions rather than to changes in regional strain rates. During the Holocene, fault displacement rates were both faster (~50%) and slower (~50%) than their million-year averages. The short-term fault data are incomplete and biased towards the faults that have moved fastest during the Holocene. The integration of different timescale datasets provides a basis for identifying active faults not observed at the ground surface, estimating maximum faultrupture lengths, inferring maximum short-term displacement rates and improving earthquake hazard assessment.
In: Earthquake Geology and Archaeology: Science, Society and Critical facilities. (Edited by Grützner, C., Pérez-López, R., Fernández-Steeger, T., Papanikolaou, I., Reicherter, K., Silva, P.G. and Vött, A.), Proceedings of the 2nd INQUA-IGCP 567 International Workshop, Corinth, 290, 148-151, ISBN 978-960-466-093-3, 2011.