Poisonous gases spewing from Mount Dieng in Central Java caused increasing alarm on Tuesday as concentrations of one of the gases breached levels deemed safe for humans.
Sutopo Purwo Nugroho, a spokesman for the National Disaster Mitigation Agency (BNPB), said that at Timbang, one of Dieng’s six craters, levels of carbon dioxide (CO2) in the air hit 0.65 percent on Tuesday, higher than the safe level of 0.5 percent and more than five times greater that the usual concentration of 0.1 percent.
“Because this is the rainy season with low temperatures, there’s a great chance the CO2 gas will accumulate with highly concentrated carbon monoxide and float two meters above the ground,” he said.
Scientists say that Timbang and Sinila have been the most active of Dieng’s craters, spouting jets of carbon dioxide and carbon monoxide and leading the BNPB to raise the eruption alert status from level 2 to level 3 on Monday.
The two gases are colorless and odorless, making them difficult to trace, and are toxic at high levels. The Indonesian Red Cross (PMI) has been distributing face masks to people in the area. Sutopo said that the Volcanology and Geographical Disaster Mitigation Agency (PVMBG) had declared a one-kilometer radius around Timbang off-limits.
Since Sunday, the government has relocated more than 1,100 people living in the area to shelters in nearby Batur subdistrict. Sutopo said that a number of small volcanic earthquakes had been detected as well, lasting from five to 15 seconds.
Surono, PVMBG chief, said that in 1979, CO2 from the Timbang crater killed 149 people. During the rainy season, the greenhouse gas stays close to the surface of the earth, making it deadlier, he added.