Mount Mantap's earthquakes kept accelerating for eight years after North Korea's last test

The explanation the team offers starts with the mountain itself. Mount Mantap's steep, heavy slopes press down on the rock beneath the peak, and the group's computer models put that rock under intense stress before any device went into it ^[11]. Six explosions damaged that already stressed rock and weakened the crust around it ^[12]. The 2017 test, with an estimated yield of 100 to 250 kilotons of TNT, effectively collapsed the top of the mountain ^[19][25]. Stress then redistributed through the damaged volume slowly, and faults slid years after the blasts stopped ^[12]. The authors wrote that the Mount Mantap sequence shows underground nuclear explosions can produce long-lasting crustal effects in a heterogeneous and critically stressed environment ^[13].

Kwang-Hee Kim, a seismologist at South Korea's Pusan National University and a co-author, said repeated underground nuclear tests have progressively disturbed and damaged the surrounding rock and changed the stresses acting on pre-existing faults ^[16]. Kim said the 2017 test did the most damage, and that once faults on the mountain were disturbed it started a domino effect ^[17].

The causal argument leans on timing and on geometry. Recorded activity grew in both frequency and magnitude after 3 September 2017 ^[18], and the located events line up along two tracks ^[9]. The century of documented quiet is the softer support ^[2]. Matched-filter detection pulls out small tremors that standard networks miss ^[5], so a historical record assembled without it is not a like-for-like background. The comparison inside the study is stronger: same stations, same method, 2008 through 2025 ^[3][4]. That catalogue opens two years after the first test ^[29].

The team detected 1,399 events and located 955 of them, about 68 percent, which leaves 444 detections with no mapped position ^[7][9][28]. Contributing stations sit between 80 and 200 kilometres from the site ^[4]. So the previously unmapped fault is drawn from roughly two-thirds of the catalogue ^[10].

The record does not show how large the sequence can get. "The phenomena they've identified and documented is a bit surprising," said Paul Richards, a Columbia University seismologist who was not involved in the work ^[21][22]. He called the situation "potentially dangerous" and asked, "Will it lead to even bigger earthquakes?" ^[23].

I would not call the crust under Mount Mantap permanently destabilised on this evidence. The paper's own term is long-lasting ^[13], and the record covers about eight years after the last test ^[30]. What the faults do after 2025 is outside it.