An Indonesian volcano shot a towering cloud of black ash high into the air today, dusting villages 25km away - its most powerful eruption since awaking from four centuries of dormancy.
Some witnesses reported seeing several hotspots at the foot of Mount Sinabung for the first time today.
Mount Sinabung's eruption last week caught many scientists off guard.
Surono, who heads the nation's volcano alert centre, said the government sent dozens of trucks to the mountain to help carry them back before today's eruption, which sent ash and debris shooting 5,000 metres into the air.
Local media said ash had reached as far as Berastagi, a district 25km from the base.
Surono said activity was definitely increasing.
Some witnesses at the foot of Mount Sinabung reported seeing an orange glow - presumably magma - in cracks along the volcano's slopes.
"It was really terrifying," said Anissa Siregar, 30, as she and her two children arrived by truck at an emergency shelter near the base, adding that the mountain shook violently for at least three minutes. "It just keeps getting worse."
Last week's first eruption caught many scientists off guard. With more than 129 active volcanoes to watch, local vulcanologists had failed to monitor the long-quiet mountain for rising magma, slight uplifts in land and other signs of seismic activity.
There are fears that the current activity could foreshadow a much more destructive explosion in the coming weeks or months, though it is possible, too, that Sinabung will go back to sleep after letting off steam.
More than 30,000 people living along the volcano's fertile slopes have been relocated to cramped refugee camps, mosques and churches in nearby villages.
But some - such as Ms Siregar, the mother who fled with her children - have insisted on returning to the danger zone to check on their homes and their dust-covered crops.
Today's eruption happened just after midnight during a torrential downpour. Witnesses said volcanic ash and mud oozed down the mountain's slopes, flooding into abandoned homes. Others saw bursts of fire and hot ash.
The force of the explosion could be felt 8km away.
Indonesia is a seismically charged region because of its location on the so-called "Ring of Fire" - a series of fault lines stretching from the Western Hemisphere through Japan and Southeast Asia.
It has recorded some of the largest eruptions in history.
The 1815 explosion of Mount Tambora buried the inhabitants of Sumbawa Island under searing ash, gas and rock, killing an estimated 88,000 people.
The 1883 eruption of Krakatoa could be heard 3,200km away and blackened skies region-wide for months. At least 36,000 people were killed in the blast and the tsunami that followed.