At 3:56 in the morning on 18 September 2024, a seismograph at the Geophysical Survey of the Russian Academy of Sciences recorded a magnitude 2.5 to 2.8 event in Tver Oblast. It was not an earthquake. It was the secondary detonation of an estimated 30,000 tonnes of artillery shells, glide bombs, and missiles inside the 107th Arsenal of the Main Missile and Artillery Directorate, an ammunition depot 33 kilometers northwest of the small town of Toropets. The primary blast left a crater 82 meters across. The shockwave shattered windows in towns kilometers away. From space, NASA's fire monitoring satellites detected the burn area for days afterward.
Ukraine's Security Service (SBU), Defence Intelligence (HUR), and Special Operations Forces jointly claimed responsibility for the attack, conducted by long-range one-way attack drones launched from Ukrainian territory more than 480 kilometers to the south. The Russian Defense Ministry's official statement was that all 54 drones aimed at western Russian regions had been intercepted. The crater visible on commercial satellite imagery the following morning suggested otherwise. Forbes reporter David Axe estimated as many as 100 drones had been launched in the operation. The blast wave was modeled by analysts at a TNT-equivalent of somewhere between 200 and 240 tons in the largest single explosion, though some assessments using the seismic data ran much higher — possibly 1.3 to 1.8 kilotons across the cascading detonations.
The 107th Arsenal had been substantially modernized after 2010. Russian state media had described it as a flagship facility, with new hardened bunkers, environmental compliance, and — according to a Russian deputy defense minister quoted in 2018 — defenses adequate against missile strikes and even, the minister claimed, 'a small nuclear attack.' Satellite imagery between 2018 and 2024 showed the storage capacity nearly doubling. NBC News reported that KAB glide bombs were stored at the site. Estonian intelligence later assessed that Iskander tactical ballistic missiles, Tochka-U missiles, and large stocks of artillery ammunition — including, by some accounts, North Korean shells supplied to Russia in 2023 and 2024 — were among the inventory destroyed. Colonel Ants Kiviselg, head of the Estonian Defense Forces Intelligence Center, estimated on 20 September that the strike had eliminated the equivalent of two to three months of Russia's ammunition supply for the front.
Russian officials reported 13 injured. Independent reporting, including from the Belarusian outlet Charter 97, suggested the actual military death toll inside the depot may have been substantially higher — though precise figures were never confirmed and may never be. Local civilians were evacuated from villages near the depot as fires continued to burn for days; the secondary detonations continued through 21 September, when NASA imagery captured a second extensive fire south of Toropets in addition to the still-burning original blaze east of the town. The depot, the surrounding forest, and the immediate landscape took weeks to settle. The shells that had been stockpiled there had been intended for use against Ukrainian cities and Ukrainian soldiers; many of them had already arrived from North Korea by rail through eastern Russia, the product of Pyongyang's deepening alignment with the Russian war effort.
The Toropets explosion was, by the measurements available, one of the largest single conventional munitions events of the war up to that point — Newsweek called it possibly the 'biggest single event' in the conflict by yield. It came at a time when Ukraine was steadily extending the range and accuracy of its drone fleet to reach targets deep inside Russia, partly to compensate for restrictions Western allies had placed on the use of NATO-supplied missiles for cross-border strikes. Six weeks earlier, on 6 August 2024, Ukrainian troops had crossed into Russia's Kursk Oblast in a ground incursion. Toropets was, in effect, an air-domain version of the same argument: that the war Russia had brought to Ukrainian cities could be returned, at long range, to Russian territory.
Russian authorities did not publish an official damage assessment. Newer satellite imagery published by Newsweek on 24 September showed an approximately 270-foot crater and significant damage to surrounding bunker and storage structures. The site was eventually rebuilt in part, but with reduced capacity, and Russia's Tver Oblast munitions logistics were forced to reroute through other depots — at Tikhoretsk in Krasnodar Krai, also struck by Ukrainian drones the same week, and at facilities further from the front. The wider war ground on. The dead at Toropets, on both sides of the lines, were among many; the depot's destruction was a single chapter in a long campaign of Russian and Ukrainian strikes on each other's military infrastructure. The seismic record from that September morning remains: a small earthquake that wasn't, registered in soil, west of Moscow, in the third autumn of the full-scale invasion.
Located at 56.506°N, 31.702°E in Tver Oblast, Russia, west of Moscow and east of the Latvian border. The depot site sits in flat forested country approximately 33 km northwest of the town of Toropets. Active military airspace remains restricted; civil overflights of the Tver region typically route well to the south or north. From altitude, the area is largely roadless taiga and small lakes.