November 30, 2022 Tsunami: Lake Taupo, North Island, New Zealand

Ref #13387, #13392, #13393:

A small tsunami was generated in Lake Taupo on the night of the M5.7 earthquake. The waves travelled across the lake and surged a few metres across many beaches, leaving behind some strands of pumice, sticks and sand. The larger surge at Wharewaka Point, where the beach is known to have retreated by some 20 m, may be associated with a possible underwater landslide [...] We have surveyed the deposits and found that the tsunami wave pushed debris almost 1 metre above the lake level, when it reached the western shores at Kuratau and on the east side of the lake at Motutere. In some places, the lakeshore had been undercut by waves and small areas had collapsed a metre or so back. The tsunami had less impact on the northern shores, for example at Whakaipo Bay where the wave left pumice debris less than 30 cm higher and less than a metre inland from the high-water mark. Little or no change was seen at Kinloch, Acacia Bay, or in the western bays. However, major changes happened at Wharewaka point near Taupo, with substantial washout of the foreshore and beach, and pumice debris stranded to a maximum of about 40 m inland from the lake.

It is possible an underwater landslide occurred at the location of the popular swimming beach [Wharewaka Point?], causing 170 m of the shoreline to subside into the lake, with a maximum retreat of up to 20 m. Whilst still under investigation it is possible that the collapse of the beach into the lake drew water in behind it, generating the local tsunami that washed up onto the picnic area behind it. Underwater landslides are known to be some of the largest landslides on earth and can trigger tsunamis, however, there is currently no evidence to suggest the Wharewaka Point landslide generated the larger lake-wide tsunami observed following this earthquake.

Ref #13388:

Two large, four-person pedal boats that were pulled up onto the grass near the area of erosion, were torn from their chains, washed onto rocks and destroyed by a surge of water, thought to be a tsunami, during the swarm on Wednesday night and Thursday morning.