MOUNT MERAPI, Indonesia -- Indonesia's most dangerous volcano showed no sign of tiring Tuesday, belching clouds of black smoke as fiery lava lit up its cauldron. Scientists warned that the slow but deadly eruption could continue for weeks, like a "marathon, not a sprint."
The activity was accompanied by rumbling at 21 other active volcanos in Indonesia, twice the number usually on the government's "watch" list, which raised questions about what's causing the uptick along some of the world's most volatile fault lines.
No casualties were reported in Mount Merapi's latest blast, which came as Indonesia struggled to respond to an earthquake-generated tsunami that devastated a remote chain of islands. The two disasters unfolding in separate parts of the country have killed nearly 470 people and strained the government's emergency response network.
In both events, the military has been called in to help.
Indonesia, a vast archipelago of 235 million people, is prone to earthquakes and volcanos because it sits along the Pacific "Ring of Fire," a horseshoe-shaped string of faults that lines the western and eastern Pacific.
Merapi, one of the world's most active volcanoes, has killed 38 people since springing back to life just over a week ago.
There have since been more than 10 large eruptions, including a violent burst Monday that appears to have eased pressure building up inside the crater by creating a vent for magma to escape.
"There's no way of knowing for sure, of course," said Safari Dwiyono, who has observed the mountain for more than 15 years. "But based on what we've seen in the last few days, we're hoping there won't be a massive explosion. It's looking like we're in for a marathon, not a sprint."
The nearly 70,000 villagers evacuated from the area around Merapi's once-fertile slopes -- now blanketed by gray ash -- have been told they could be expected to stay in crowded government camps for at least three more weeks.
More than 800 miles to the west, meanwhile, a C-130 transport plane, six helicopters and four boats were ferrying aid to the most distant corners of the Mentawai islands, where last week's tsunami destroyed hundreds of homes, schools, churches and mosques. The tsunami death toll stood Monday at 431, the National Disaster Management Agency said on its website.
President Susilo Bambang Yudhoyono said relief efforts must be sped up, expressing dismay that it took days for aid to reach the isolated islands, though he acknowledged that violent storms were largely to blame.
Last week's killer wave was triggered a 7.7-magnitude earthquake along the same fault that caused the 2004 temblor and tsunami that killed 230,000 people in a dozen countries. The fault line, along the west coast of Sumatra island, is the meeting point of the two of the Earth's dozen major plates, which have been pushing against and under each other for millions of years, causing huge stresses to build up.
Both earthquakes and volcanos can result from the release of these stresses. As plates slide against or under each other, molten rock can break the surface via a volcano or the energy can be released in an earthquake.
The government has raised alert levels of 21 other volcanos to the second- and third- highest levels in the last two months because they have shown an increase in activity, state volcanologists Syamsul Rizal said Monday.
That's twice the number usually on the government "watch" list.
Geophysicist Pall Einarsson of the University of Iceland said the activity increasingly seems to indicate that the volcanos could be affecting neighboring ones, and that this was a new idea for volcanologists.
"If it's true that there are over 20 volcanos demonstrating increased levels of seismic activity, then that is something we should pay attention to," agreed Brent McInnes, a professor at Australia's Curtin University, adding however that he has not yet seen the raw data.
He said such an increase could indicate "a major plate restructuring" -- a shift in the plates' position, rather than simply the usual jostling.
Others were quick to point out, however, this could just be a normal, random fluctuation of volcanic activity.