Mount Merapi, Indonesia ? Clouds of gray ash rumbled down the slopes of Indonesia’s most volatile volcano Saturday in its most powerful eruption of a deadly week, prompting soldiers to force reluctant villagers to evacuate amid fears of a larger blast.

On the other side of the archipelago, storms again prevented aid deliveries to increasingly desperate survivors of a tsunami — including a teenage girl with an open chest wound — that killed 449 people in the Mentawai islands. Relief workers found some comfort, however, when the number of missing dropped by half to 163 as searchers discovered more survivors and villagers who had fled to the hills returned home.

The simultaneous catastrophes have severely tested the emergency response network. Indonesia lies in the Pacific “Ring of Fire,” a cluster of fault lines prone to earthquakes and volcanic activity.

Mount Merapi, which sprang back to life early this week, unleashed a terrifying 21-minute eruption early Saturday, followed by more than 350 volcanic tremors and 33 ash bursts, said Surono, chief of the Center for Volcanology and Geological Hazard Mitigation.

The latest spewing of the notoriously unpredictable volcano forced the temporary closure of an airport and claimed another life, bringing the death toll this week to 36.

At least 47,000 people have fled the mountain’s wrath, according to the National Disaster Management Agency.