Tsunami models underestimated shockwave from Tonga eruption

The volcanic eruption in Tonga this month unleashed an atmospheric shockwave that radiated out at close to the speed of sound, pushing large waves across the Pacific to the shores of Japan and Peru, thousands of kilometres away.

Forecasting models and warning systems, designed primarily to assess earthquake-triggered waves, did not account for the boosting effects of the shockwave. It was a critical flaw in these systems, scientists said, leaving them unable to predict exactly when the waves would hit land.

"The trans-Pacific and global waves arrived earlier than forecast, which (was) terrible for distant shorelines," said civil engineer Hermann Fritz at Georgia Tech University, who studies tsunamis.

The Hunga Tonga-Hunga Ha'apai volcano eruption triggered a tsunami that destroyed villages and resorts and knocked out communications for the South Pacific nation of about 105,000 people. Three people have been reported killed.

However Tongans were well equipped to deal with the tsunami. The small island nation is considered among the most prepared for natural disasters, with years of tsunami drills under its belt, and many people knew to evacuate to higher ground.