"The National Disaster Mitigation Agency (BNPB) will immediately build temporary housing," said Coordinating Minister Pratikno.
Volcanic thunderstorms arise during an eruption due to high temperatures that heat gas ions.
The rock structure is estimated to be 20 to 30 million years old.
Past records show that several volcanic eruptions in Indonesia have claimed lives, have other impacts in the form of economic and social aspects disruption on the community, as well as damage to infrastructure and other development results
"Other likely threats are the emission of toxic gases around the crater area. If an eruption occurs and the material falls on the slopes of the volcano, then there is a likely threat of cold lava when it rains,"
Located in the eastern part of Java, Semeru is the highest volcano on the island at 3,676 mdpl, and it's also one of the most active.
Two victims were found hugging each other during evacuation after the Mount Semeru eruption.
