Mount Baekdu is on the verge of erupting, a geologist said Sunday.

Earth science study professor Yoon Seong-hyo from Pusan National University said the highest mountain on the Korean peninsula needed to be monitored closely.

The height of caldera has risen one centimeter since last July, said Yoon, who has been monitoring the mountain with an electronic distance measurement (EDM) device.

“The mountain’s height has risen about 10 centimeters between 2002 and 2005,” Yoon said. “It then began to sink in 2009. The shift changed only recently, which is significant.”

The temperature from the caldera’s geyser had been around 70C, but recently rose to 83C, Prof. Yoon said. The helium concentration rate had also recently jumped from 6.5 times that of the normal atmosphere from 2002 to 2005 to seven times.

“All these signs indicate the magma inside the mountain is moving upward,” Yoon said. “We need to monitor the mountain closely.”