New database sheds light on prehistoric tsunamis affecting New Zealand
The scientific records of palaeotsunamis to have affected New Zealand shores can now be accessed in a new one-stop information shop.
A palaeotsunami is a tsunami that occurred before written records existed and has been discovered by investigating geological and anthropological evidence.
This information, which was previously stored in old spreadsheets or historic documents, has been transferred to an interactive map and database that enables users to search for palaeotsunami records by location, time and strength of scientific validity. The map reveals palaeotsunamis have occurred along almost all parts of the New Zealand coastline but there are greater concentrations on the east and west coasts of the upper half of the North Island.
The free New Zealand Palaeotsunami Database is based on the work of former NIWA scientist Professor James Goff, now based at the University of New South Wales in Australia. It is being provided by NIWA with funding assistance from the Ministry for Civil Defence and Emergency Management.
Understanding tsunami risk from past events
Project leader and NIWA scientist Darren King said the aim of the database was to increase awareness of New Zealand’s tsunami hazard and help in the analysis of palaeotsunami information.
“If you are assessing tsunami risk, it is helpful to know the history of past events in your area. This is an easy way to look at multiple records to understand risk profiles based on the available evidence.”
Mr King said many of New Zealand’s palaeotsunami records had been sitting in spreadsheets, or held in information that hadn’t previously been published, such as reports, logs and old historical documents.
“The information was difficult to look at, there was limited access to it and so few people were using it.
“We think this database has a broad audience including environmental managers, civil defence staff, researchers and the wider public who now have an easy way to look at multiple records, explore the data and look at what has happened in the past,” Mr King says.
Levels of evidence
The assortment and age of records means some are regarded with less confidence than others, but researchers have included a colour coding system on the map to indicate the level of scientific veracity.
Along with the location, each record may include information on how far the tsunami travelled inland, where the information came from, maximum water heights, what damage was caused, the strength of the evidence and the date range of when it occurred. Records date back to pre-historic times. Mr King says there is strong evidence that New Zealand’s biggest tsunami occurred between 1450 and 1480AD at Henderson Bay, Northland where deposits reached some 32m above sea level and extended about 1000m inland.
Mr King says the database would be added to as new research was undertaken and includes the latest published palaeotsunami research from New Zealand confirming evidence of three palaeotsunamis at Mataora-Wairau Lagoon in Marlborough in the past 2000 years.
Dr Goff said: “The intention of the database was always to have it freely available to everybody and so it is has been wonderful to work with such a dedicated team and see this project come to fruition.”
The New Zealand Palaeotsunami Database can be found at: http://ptdb.niwa.co.nz
The database has been set up by NIWA, Environment Canterbury and eCoast Marine Consulting and Research with the interactive web-based portal developed by dumpark data visualisation.
James Goff, Honorary Professor of Tsunami Research, UNSW Australia
Ph +44 (0) 7746 245 270