Predecessor to New Zealand's largest historic trans-South Pacific tsunami of 1868 AD James Goff a, ⁎, Scott Nichol b,1 , Catherine Chagué-Goff a , Mark Horrocks b,c , Bruce McFadgen d , Marco Cisternas e a Australian Tsunami Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia b School of Environment, The University of Auckland, Private Bag 92019, Auckland, New Zealand c Microfossil Research, 31 Mont Le Grand Rd, Mt Eden, Auckland 1024, New Zealand d School of Māori Studies, Victoria University of Wellington, PO Box 600, Wellington, New Zealand e Escuela de Ciencias del Mar, Pontificia Universidad Catolica de Valparaiso, Casilla 1020, Valparaiso 1, Chile abstract article info Article history: Received 18 December 2009 Received in revised form 11 May 2010 Accepted 11 May 2010 Available online 4 June 2010 Communicated by D.J.W. Piper Keywords: New Zealand Chile 1604 AD 1868 AD multi-proxy South Pacific Multiproxy analyses of coastal sediments at Cape Pattisson, Chatham Island, identified evidence of two past tsunamis. The most recent event was the 1868 AD tsunami for which there is a wealth of historical evidence. We argue that the earlier event is most probably the 1604 AD South American tsunami. The chronology for these two events was established using palynological data from the Chatham Island sediments, and historical data from South America. It is unlikely that the exposed coastline of Cape Pattisson preserves evidence of earlier events, but given the historical and palaeotsunami records in South America, it seems likely that many earlier trans-South Pacific tsunamis would have struck the Chatham Islands and possibly mainland New Zealand. This is the first time that sedimentological evidence for a prehistoric trans-South Pacific tsunami has been documented in New Zealand, albeit on an outlying island. In the light of the findings on Chatham Island, a reassessment of the New Zealand palaeotsunami database indicates that there are several possible 1604 AD deposits on the east coast of both mainland islands. Further work needs to be done to determine whether these are indeed associated with the 1604 AD event. This use of data from a country with a relatively long historical record adds immense value to understanding the timing of palaeotsunamis in countries with shorter records. This technique offers an excellent opportunity to evaluate the magnitude and frequency of past trans-South Pacific tsunamis and to assess the risks posed to individual Pacific islands. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Following the Indian Ocean Tsunami (IOT) of 26th December 2004, there has been a growing recognition of the need for comprehensive historical and palaeotsunami databases (e.g. Dominey-Howes, 2007). There are now many well-established datasets that provide invaluable information (Australia: Dominey-Howes, 2007; Global: http://www. ngdc.noaa.gov/seg/hazard/tsu.shtml; Greece: Papadopoulos, 2000; Italy: Tinti et al., 2004; Pacific Northwest: Peters et al., 2003; New Zealand: de Lange and Healy, 1986; Goff, 2008). It is also recognised that these datasets must be rigorously updated, cross-checked, and validated because of their value for risk assessment. They have other uses, however, and can serve to guide researchers in their search for the potential sources of past tsunamis recorded in the geological record. In the historical record, the three most significant distantly- generated tsunamis to have affected New Zealand are from South America. They occurred in 1868 AD, 1877 AD, and 1960 AD (de Lange and Healy, 1986). The 1868 AD event was the largest of these with a northern Chilean source near Arica (http://www.ngdc.noaa.gov/seg/ hazard/tsu.shtml). The orientation of the plate boundary in this region means that subduction zone earthquakes here tend to direct tsunami waves towards the eastern coast of New Zealand and the Chatham Islands (Berryman, 2005). The 1868 AD tsunami is the earliest historically documented event with a South American source in the New Zealand database, although historical earthquake records in Chile and Peru extend back well into the 16th century (Cisternas et al., 2005). In many parts of the world, historically documented accounts do not extend far enough back in time to provide reasonable estimates of the magnitude and frequency of past tsunamis at any one location. This is especially the case for New Zealand, where the historical record only extends back to the early 1800's, requiring researchers to use palaeotsunami data, and where possible, historical data from elsewhere (Goff et al., in press). The use of historical data from other countries has proven to be highly valuable in the northern Pacific Ocean, where the 1700 AD Cascadia palaeotsunami in the Pacific Northwest of the USA was Marine Geology 275 (2010) 155–165 ⁎ Corresponding author. Tel.: +61 2 9385 8431; fax: +61 2 9385 1558. E-mail addresses: j.goff@unsw.edu.au (J. Goff), scott.nichol@ga.gov.au (S. Nichol), c.chague-goff@unsw.edu.au (C. Chagué-Goff), info@microfossilresearch.com (M. Horrocks), arch.research@actrix.co.nz (B. McFadgen), marco.cisternas@ucv.cl (M. Cisternas). 1 Current address: Geoscience Australia, GPO Box 378, Canberra ACT 2601, Australia. 0025-3227/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.margeo.2010.05.006 Contents lists available at ScienceDirect Marine Geology journal homepage: www.elsevier.com/locate/margeo