"Earthquake tremor has emerged and we decided to raise its danger status to a caution level at 9.15pm on Thursday," head of Volcanology and Geological Disaster Mitigation Agency (PVMBG), Muhammad Hendrasto, said when asked for confirmation here on Thursday night.
He said under the status the area as far as 10 kilometers away from the mountains peak must be sterilized and people were also advised to evacuate to safer places.
People were already gathering at evacuation centers and looked panic.
Kediri resort police deputy chief Commissioner Alfian meanwhile said that all police personnel had been deployed to evacuation centers following the development of the mountains activity.
"We are now just waiting for any instruction," he said.
He said there were around 400 police officers made ready including some vehicles to help evacuate the people.
The military (TNI) has also deployed around 1,000 of its personnel to provide help in case explosion occurs.
"We have around 700 personnel ready in addition to personnel from Infantry Brigade 16th/Wira Yudha in Kediri and Infantry Batallion 521 from Kediri," the commander of the 0809th Military Command Kediri, Lt Col Heriyadi said.
Around 66,000 people in the district of Kediri have to be evacuated in case eruption happens. These people are from four sub-districts that would be directly affected.
The danger status of Mt Kelud has changed very fast from a normal level to alert on Sunday (Feb 2) and on Monday (Feb 10) to a caution level on Thursday at 9.15pm.
Mt Kelud has erupted 25 times from the year 1,000 to 2007 leaving tens of thousands of people dead.
The last eruption of the mountain was recorded in 2007 but it was effusive in character causing the creation of a new mountain.
reporting by fiqih arfani