The central area of Mount Baekdu in North Korea has risen 18 millimeters over the past six years, showing the lack of complete stability.

A team said Wednesday that an analysis of Japanese satellite images confirmed the crater lake Cheonji at the peak rose three millimeters annually between 1992 and 1998.

Led by professors Moon Woo-il of Seoul National University and Joong-sun of Yonsei University, the team said the rise shows possible magma accumulation near the surface, though further verification is required.

Though the mountain has long been classified as a dormant volcano, the team said Mount Baekdu is hardly seen as active as the rise is fairly insignificant compared to swelling right before an eruption.