SEOUL, South Korea — Any future nuclear test by North Korea risks collapsing its mountain test site and triggering a radiation leak, South Korea’s weather agency chief said Monday.

The head of the Korea Meteorological Administration, Nam Jae-Cheol, made the comments during a parliament committee meeting in response to a lawmaker’s question about whether another North Korean test could lead to such an accident.

South Korea has detected several largely small-sized earthquakes near the northeastern nuclear test site the North used for its sixth and most powerful bomb explosion in September. Experts say the quakes suggest the area, which was also used for the North’s previous underground nuclear tests, is now too unstable to conduct more tests there.

Lee Won-Jin, a Korea Meteorological Administration researcher, said the analysis of satellite photos indicated there were landslides around the Punggye-ri test site after the September test. He also said there now might be a hollow space inside Mount Mantap, the granite peak where the North’s test site is located, citing studies of past underground nuclear tests by the United States.

Lee said the North’s past six nuclear tests were not reported to have caused any radiation damage to neighboring countries

Analysts believe North Korea will likely conduct more nuclear and missile tests to try to build a reliable arsenal of nuclear-tipped missiles capable of striking anywhere in the mainland U.S. It’s unclear when and where those tests could take place.

North Korea’s foreign minister said last month that his country could conduct a hydrogen bomb test over the Pacific Ocean.