Mount Sinabung in Karo regency, North Sumatra, erupted on Tuesday morning after being inactive for about a year. The eruption took place at 6:41 a.m., spewing ash 2,000 meters into the air in a northeast direction.

Muhammad Nurul Asrori, a Sinabung monitoring post officer, said that Tuesday’s eruption was the first since May 2018.

He said the ash spew could drift as far as 15 kilometers.

“People within the 15-km radius, both locals and tourists, should be alert to the eruption,” he said.

Asrori said that the eruption was felt until 10:44 a.m. and the ashes were still visible.

The volcano, which has been rumbling since 2010 and underwent a deadly eruption in 2016, did not have a lava dome.

“Since February 2018, we haven’t seen a lava dome in the Sinabung crater. This is why there are no hot clouds,” Asrori said.

He also warned local citizens to stay alert because the Mt. Sinabung was still under alert (level IV) of the four-level national volcano alert system.

“Nobody is allowed to do anything within a 3-km radius in the north-west sector, 4-km in the south-west sector, 7-km in the south-southeast sector, 6-km in the southeast-east sector and within a 4-km radius in the north-east sector,” Asrori said.

Pelin Depari, a villager of Lau Kawar, said he was shocked to learn that Mt. Sinabung had erupted again.

“The ash covers everything including our plantations and it's quite thick,” he said.

Karo Disaster Mitigation Agency (BPDB) head Martin Sitepu said four districts were badly affected by the Sinabung eruption, namely Simpang Empat, Namanteran, Kabanjahe and Berastadi.

“Many villages in the four districts were affected by the ashes. This surprised us because it’s been a year since Sinabung was active,” he said.

Martin said the eruption hit the local economy hard because the ash damaged plantations. He said his agency was deploying several fire trucks to help water down the ash and wash it away from the plantations.

“It will take time to clean up the ash because it's thick and the exposed area is quite large,” he added.

Karo 0205 military district commander Lt. Col. Taufik Rizal, who is also a member of the Sinabung Eruption Task Force, called on villagers to stop their activities in the mount’s red zone. “It is still dangerous. They’d better stay away,” he said.

Sinabung roared back to life in 2010 for the first time in 400 years. After another period of inactivity it erupted once more in 2013 and has remained highly active since.

In 2016, seven people died in one of Sinabung's eruptions, while a 2014 eruption left 16 people dead.

Indonesia is home to about 130 volcanoes because of its position on the Ring of Fire, a belt of tectonic plate boundaries circling the Pacific Ocean where frequent seismic activity occurs.