Tsunamis only happen in the ocean, right?

Actually, tsunamis can happen in lakes too. While they are rare, NIWA and GNS Science researchers have been out on Lake Tekapo mapping the lake bed to find evidence of past underwater landslides that could have created tsunamis. 

The research has found evidence for large underwater landslides, most likely triggered by earthquakes, happening about once every thousand years over the lake’s 12,000-year history. Some of these landslides may have created tsunamis several metres high at the lake shore. 

What does this mean for Lake Tekapo? 

Like any coastal area or lake shore in New Zealand, if you feel a long (more than a minute) or strong (hard to stand up) earthquake, stay away from the lake shore and move to higher ground if you can. 

There is only a small chance that a tsunami will have been created, but if it has, it would cause the lake level to rise and fall rapidly. It would not necessarily flood land, especially if the lake level is low – it may just affect the lake beach or create strong currents in the lake. 

Next steps 

Environment Canterbury and Mackenzie District Council are now working together to understand which parts of the Lake Tekapo lake shore are most vulnerable, and how best to use the new information. 

A community meeting will be held on Wednesday 23 May at 7pm, at the Tekapo Community Centre, with NIWA and GNS Science researchers, to talk about the research and discuss the next steps with the community. All residents are welcome to attend. 

Read the full report and more information about what this research means for Lake Tekapo.