Indonesian scientists on Thursday were closely monitoring three volcanoes that have rumbled into life — activity they link to last December's monster earthquake off the coast of Sumatra Island (search) and the countless other powerful temblors that followed.

Thousands of people have been evacuated from the slopes of Mount Talang (search) in west Sumatra, which erupted Tuesday, showering dust over nearby villages and spreading panic among villagers.

On Thursday, many of the villagers returned home to tend their crops and animals, but were planning to return to makeshift camps and public buildings like schools and mosques for the night.

Authorities have declared the other two — Anak Krakatoa off Sumatra's southern tip and Tangkuban Perahu in west Java province — off limits to hikers, citing a build up of gas inside the peaks and increase in volcanic eruptions.

Scientists have been dispatched to all three mountains, but there were no signs of imminent eruption, said Syamsul Rizal, a government volcanologist.

Rizal, who was speaking from a monitoring station on Tangkuban Perahu (search), said he suspected that "the activities at these volcanoes were triggered by the Dec. 26 tremor under the Indian Ocean seabed of Sumatra."

The 9.1 magnitude earthquake in December triggered the Indian Ocean (search) tsunami. Three months later, an 8.7 magnitude quake erupted from the same fault line, killing more than 600 people on islands off Sumatra's west coast.

The mountains are among at least 129 active volcanoes in Indonesia, the world's largest archipelago nation. The country is especially prone to seismological activity because it is part of the Pacific "Ring of Fire" — a series of volcanoes and fault lines stretching from the Western Hemisphere through Japan and Southeast Asia.

Anak Krakatoa (search) is a small volcanic island that appeared in the 1930s on the site of the former volcano of Krakatoa, which produced the world's most powerful explosion when it erupted in 1883 and killed an estimated 36,000 people.

Anak Krakatoa — "Krakatoa's Child" — erupted repeatedly in 1999, spewing volcanic gases and rocks into the air.