Villagers were scared when Mount Talang started spewing ash
About 25,000 people have fled from the site of a volcano which has sprung to life on Indonesia's Sumatra island.
The increasing activity on Mount Talang coincides with a string of earthquakes on Sumatra in recent weeks.
The island is still struggling to cope after last year's huge earthquake and tsunami, which killed at least 120,000 people in the province of Aceh.
Officials are also monitoring a second volcano, Tangkuban Perahu on Java island, which began rumbling overnight.
While there have been no evacuations, tourists and stall-holders have been kept away from Tangkuban Prahu.
"The status of Mount Talang is now at top alert," local vulcanologist Surono told Reuters new agency.
The mountain, which is 40 km (25 miles) east of Padang, was spewing ash 500m (1,640 feet) into the air on Tuesday, although not as forcefully as it was the day before, he said.
Residents from villages around the volcano have now been evacuated, although many are reportedly returning to their homes during the day to tend their crops.
"The volcano has not yet spewed lava from the crater, but in order to anticipate such an incident, we have evacuated those living around the mountain to safer areas," district chief Djamawan Fauzi told the Associated Press.
Local villager Syafrudin described the volcano's sudden reawakening as "like the end of the world".
"I first heard the rumble and then the ground started shaking... then there's smoke and sparks. We all ran in fear," he told Reuters.
Indonesian President Susilo Bambang Yudhoyono is due to visit the region later on Wednesday to try to calm the inhabitants' fears, his spokesman said.
Scientists have warned of increased seismic activity in Indonesia, while the tectonic plates that make up the earth's crust realign following the magnitude 9 earthquake in December which caused the devastating tsunami.
"The plates' movements release energy underground, and the energy could add to the activity of many volcanoes on Sumatra, but it doesn't mean this will trigger an eruption," said Surono.
Indonesia, especially Sumatra, has suffered many aftershocks since the 26 December earthquake.
A tremor on 28 March killed at least 1,200 people, many on the island of Nias, off Sumatra's west coast.