After North Korea detonated its largest nuclear device beneath Mount Mantap in 2017, scientists weren’t surprised to detect a few earthquakes in the immediate aftermath of the underground test. A massive explosion fractures and deforms surrounding rock, typically triggering small aftershocks that fade away quickly as the crust adjusts. But years later, the crust around the Punggye-ri test site was still restless, according to a new study. Rather than fading away, earthquake activity increased over the following years, the researchers report. Even in 2025, small earthquakes were occurring along two suspected faults near Mount Mantap, some as far as 20 to 30 kilometers from the test site. Learn more: scim.ag/46zOV0w