The volcano on the Spanish island of La Palma is at its most active since erupting, officials have said.
The cone of the Cumbre Vieja volcano had partially collapsed on Monday, sending new lava flows towards previously unaffected areas.
The Canary Islands Volcanology Institute (Involcan) stated that "a giant lava fountain" of molten rock has gushed out of the volcano.
The rivers of lava rolling down the hillside are up to almost 3 kilometres wide, authorities said.
"We are at the moment of greatest activity," said Involcan spokesperson David Calvo.
The crater collapse on Monday also sent a volcanic ash cloud high over the Spanish Canary Islands, as authorities prepared to evacuate more residents in the municipality of Los Llanos de Aridane.
Around 7,500 have been forced from their homes since the volcano first erupted on September 19. Lava flows have partially destroyed more than 2,000 buildings and covered more than 900 hectares of mostly farmland.
New fissures and side vents cracked open along the volcano’s slopes over the weekend, allowing more molten rock to escape.
Scientists last week counted more than 800 earthquakes of varying magnitude on La Palma, most of them not felt by residents.
Though most of the island so far is unaffected by the eruption, parts of the western side where the lava fields are expanding face an uncertain future.