Tsunami hazard for the Bay of Plenty and eastern

NIWA Client Report: HAM2004-084 June 2004

NIWA Project: BOP04216

Tsunami hazard for the Bay of Plenty and eastern Coromandel Peninsula

R.G. Bell (NIWA) J. Goff (GeoEnvironmental Consultants Ltd) G. Downes (GNS) K. Berryman (GNS) R.A. Walters (NIWA) C. Chagué-Goff (NIWA) P. Barnes (NIWA) I. Wright (NIWA)

Prepared for Environment Bay of Plenty Environment

By

National Institute of Water & Atmospheric Research Ltd P O Box 11 115, Hamilton, Phone +64-7-856 7026, Fax +64-7-856 0151, www.niwa.co.nz

GeoEnvironmental Consultants Ltd 11 The Terrace, Governors Bay, Lyttelton RD1, New Zealand Phone +64-3-329 9533, Fax +64-3-329 9534, [email protected]

Institute of Geological & Nuclear Sciences Ltd P O Box 30 368, Lower Hutt, New Zealand Phone +64-4-570 1444, Fax +64-4- 570 4600, www.gns.cri.nz

NIWA Client Report: HAM2004-084 June 2004 NIWA Project: BOP04216

 All rights reserved. This publication may not be reproduced or copied in any form without the permission of the client. Such permission is to be given only in accordance with the terms of the client's contract with NIWA. This copyright extends to all forms of copying and any storage of material in any kind of information retrieval system.

Contents

Executive Summary iv

1. Introduction 1 1.1. The Brief 1 1.2. Report content 2

2. Tsunami—a natural hazard 3 2.1. Definitions 3 2.2. Tsunami wave behaviour 5 2.3. Tsunami risk 6

3. Historical tsunami events 7 3.1. Historical catalogue of events 7 3.2. Commentary on effects of substantial historical tsunamis 17 3.2.1. 1868 Peru tsunami 17 3.2.2. 1877 Chile tsunami 20 3.2.3. 1960 Chile tsunami 22 3.3. Summary of historical record 25

4. Paleo-tsunamis 27 4.1. (Figures 5-6) 27 4.2. Waihi Beach (Figures 7-11) 30 4.3. Ohiwa Harbour (Figures 12-13) 36 4.4. Jacobs Creek (Figures 14-16) 39 4.5. Summary (Figure 17) 43

5. Tsunami sources (Bay of Plenty and eastern Coromandel) 47 5.1. Distant source–national impact tsunamis 48 5.2. Regional and local tsunami sources 51

6. Tsunami amplification and resonance along the coast 58 6.1. Amplification and resonance 58 6.2. Resonance: causes and effects 59 6.3. Determining areas of resonance (Bay of Plenty and eastern Coromandel) 60 6.4. Discussion of Bay of Plenty and eastern Coromandel resonances 61 6.5. Evaluation of the tsunami potential from local and regional sources 65

7. Summary of the tsunami hazard for Bay of Plenty and Coromandel 67 7.1. Tsunami hazard study 67 7.2. Paleo-tsunami record 67 7.3. Historical tsunami record 68 7.4. Regional tsunami hazard profile 69 7.5. Local and regional sources of tsunami 69

7.6. Locations in the region vulnerable to distant or regional source tsunami 71

8. Glossary 73

9. References 75

10. Appendix 1: Recollections of the May 1960 Chilean tsunami in by Howard Pascoe ( resident). 81

Reviewed by: Approved for release by:

Michelle Wild (NIWA) Doug Ramsay (NIWA)

Ursula Cochran (GNS)

Formatting checked

Executive Summary

Environment Bay of Plenty (EBOP) and Environment Waikato (EW) joined together to set up a three- year Joint Tsunami Research Project to assess the tsunami hazard and associated risk for the eastern seaboard of the Waikato/Bay of Plenty region from to East Cape.

The Year 1 phase was carried out by GeoEnvironmental Consultants Ltd, involved field investigations of paleo-tsunami deposits through the collection of sediment cores and partial laboratory analysis. The methodology and interim resu