The molten rock fell from a cliff 100 metres high and created a plume of black smoke when it came into contact with the water.
An exclusion zone of two nautical miles has been declared around where the lava was expected to enter the sea and nearby residents have been warned not to leave their homes.
Yesterday, the island registered a total of 29 earthquakes, ranging from 2-3.3 on the Richter scale.
When the volcano last erupted in 1971, one man was killed by inhalation of its toxic gases.
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