A tsunami hit the Kingdom after the volcano erupted for eight minutes, throwing clouds of ash into the sky.
Waves flooded the capital, Nuku'alofa, where video footage has shown water engulfing buildings.
Communications with Tonga has been down since 6.30pm yesterday, with reports that power had been cut in the capital.
Tongan authorities should have a clearer picture this morning of the scale of the damage from Saturday's volcanic eruption and tsunami.
