The country’s geophysics agency raised the alert status for the mountain to the highest level due to activity that produced more than 300 tremors within a six-hour period.

Rising magma also caused the temperature of the crater lake to soar.

About 350,000 people live within the fertile 6-mile (10 km) danger zone around the volcano, where they grow coffee, sugar cane and various tropical fruits. Some tend to their cattle as they graze on the volcano's slopes.

Scientists warned that those ignoring evacuation orders were placing themselves at grave risk from an explosive eruption.

On Thursday, seismic activity within Mount Kelud subsided, but officials cautioned those who live near the volcano not to let down their guard.

"Its seismic activity has cooled down today, but that could also mean that Mount Kelud is saving its energy for a big eruption," Saleh Setiawan, an official at the volcanology center in Bandung, told reporters.

Kelud last erupted in 1990, killing dozens of people, and is regarded as the most active of Indonesia's many volcanoes. An eruption in 1919 killed about 5,000 as it ejected scalding water from its crater lake.

Photo: Dan Dzurisin - U.S. Geological Survey         Digg This