Lakes pose potential tsunami threat

Pictured: Mapped image of Lake Tekapo’s lake bed.

Recent research led by NIWA’s marine geologist Dr Joshu Mountjoy has provided the most advanced mapping of a New Zealand lake to date which highlights tsunamis as a possible hazard to lakeside towns.

Research from Lake Tekapo revealed that the lake has a dynamic bed with a huge range of processes shaping it, highlighting the tsunami risk to lakeside towns caused by landslides.

NIWA found evidence that many landslides had occurred at the same time and believe this had happened during large earthquakes.

The results of the study have recently been presented to the Tekapo community, to raise awareness of the hazard as tsunami waves have the potential to damage infrastructure and cause flooding.

Dr Mountjoy said: "Most people think of tsunamis as ocean-based, but they are just as capable of happening in lakes, although little work has been done on this worldwide. Given New Zealand's geological make-up, this is something New Zealand communities should be more aware of."

He urges that if people feel a long or strong earthquake they should move to higher ground and encourage others to do the same.

Researchers hope that the Lake Tekapo study can be used as a basis for research on tsunami hazards in other large NZ lakes such as Wakatipu, Wanaka and Taupo.

According to NIWA: "This is not a unique hazard to Lake Tekapo, other large and popular lakes in the South and North Islands may experience tsunamis at some point."

Although Lake Wanaka is the fourth largest lake in New Zealand Dr Mountjoy did not have any specific information on the landslide tsunami hazard for Lake Wanaka and knows of no specific work being done to address this yet.

The Hunter Valley Fault under Lake Hawea is likely to impact Hawea township and possibly the hydro control dam too if major landslides do occur.

Alpine Fault Magnitude 8 project believes that there is a high likelihood of landslide triggered tsunamis in one or more of the large former glacial lakes including Wanaka and Hawea.

Just this week, the Minister of Civil Defence Kris Faafoi has just announced funding for five additional projects in regional NZ to enhance resilience to natural hazards, giving the West Coast Tsunami Modelling $16,530.

Pictured: Mapped image of Lake Tekapo’s lake bed.

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