Nat. Hazards Earth Syst. Sci., 12, 2051–2064, 2012 www.nat-hazards-earth-syst-sci.net/12/2051/2012/ Natural Hazards doi:10.5194/nhess-12-2051-2012 and Earth © Author(s) 2012. CC Attribution 3.0 License. System Sciences Late Holocene landscape change history related to the Alpine Fault determined from drowned forests in Lake Poerua, Westland, New Zealand R. M. Langridge1, R. Basili2, L. Basher3, and A. P. Wells4 1GNS Science, P.O. Box 30-368, Lower Hutt, New Zealand 2Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Rome, Italy 3Landcare Research NZ Ltd., Private Bag 6, Nelson 7042, New Zealand 4c/-2 McLennan Rd, R D Hawea, Luggate, New Zelaand Correspondence to: R. M. Langridge (
[email protected]) Received: 25 July 2011 – Revised: 5 March 2012 – Accepted: 14 March 2012 – Published: 26 June 2012 Abstract. Lake Poerua is a small, shallow lake that abuts lake. Radiocarbon chronologies built using OxCal show that the scarp of the Alpine Fault on the West Coast of New a series of massive landscape changes beginning with fault Zealand’s South Island. Radiocarbon dates from drowned rupture, followed by landsliding, fan sedimentation and lake podocarp trees on the lake floor, a sediment core from a expansion. However, drowned Kahikatea trees may be poor rangefront alluvial fan, and living tree ring ages have been candidates for intimately dating these events, as they may be used to deduce the late Holocene history of the lake. Rem- able to tolerate water for several decades after metre-scale nant drowned stumps of kahikatea (Dacrycarpus dacry- lake level rises have occurred.