Tsunami science

Summary

This research identifies potential lake tsunami and seiche sources for the Mackenzie Basin lakes. These include fault movement under the lakes, landslides into the lakes, delta collapses, and earthquake waves passing through the lakes from more distant earthquakes.

Fault movements under lakes Ruataniwha, Alexandrina and Tekapo could produce tsunamis with wave heights of up to 3m. Potential landslides into lakes Ōhau, Pukaki and Tekapo could produce localised tsunamis with wave run-up heights of up to 25m. Delta collapses are a possibility in lakes Ōhau, Pukaki and Tekapo, and there is evidence in lake sediments of these occurring in the past, but there is not enough data to estimate their size or the size of a resulting tsunami. Earthquake waves from historic large earthquakes in the South Island have not caused significant seiches ('sloshing' of water backwards and forwards) in the lakes, but this is still a possibility in future large earthquakes.

Emergency management relevance

This research contributes to our understanding of lake tsunami hazards in the Mackenzie Basin.

Additional information

Authors: Kate Clark, Phaedra Upton, Brenda Rosser, Delia Strong, Jon Carey

Date: 2015

Funders: Environment Canterbury

Format: GNS Science report

Reference: Clark, K. J., Upton, P., Carey, J., Rosser, B., Strong, D. (2015). Tsunami and Seiche Hazard Scoping Study for Lakes Tekapo, Pukaki, Ohau, Alexandrina and Ruataniwha, GNS Science Consultancy Report 2014/227. Environment Canterbury report R15/39.