OSINT

Note This post was written with the help of an LLM. Unless stated otherwise, times are China Standard Time (UTC+8). Around noon on 2026-10-08, a fire started near Nömrög (Нөмрөг) in Khalkhgol soum, Dornod Province, Mongolia, about 27 km from the China–Mongolia border. Two geostationary satellites put the ignition between 11:41 and 11:51, and Mongolia’s National Emergency Management Agency (NEMA) received the call at 11:551. The Mongolian telecom operator Mobicom is a subsidiary2 of Japan’s KDDI. Its statement of 10-123 says that a vehicle caught fire while a group was handing over telecommunications work at border outposts and the Sümber border crossing and surveying local conditions, and that this started the grassland fire. The statement4 of Mongolia’s General Authority for Border Protection says the vehicle caught fire “due to the carelessness of citizens who entered the border zone”. The Dornod Province police department began investigating5 the cause of the fire on 10-17; as of 10-19 no findings have been published. The fire peaked twice, on the evening of 10-10 and during the day on 10-11, and on 10-11 and 10-12 its front reached the border west of Arxan City, Hinggan League, Inner Mongolia. After a cold front passed early on 10-12 the fire weakened. Residual burning continued intermittently inside the Mongolian fire area until the afternoon of 10-15, after which the satellites detected no more fire pixels; NEMA declared the fire fully extinguished at 07:00 on 10-166. The burned area is about 4,900 km². Montsame, quoting the Mongolian emergency services, reports that about 80% of the Nömrög Strictly Protected Area burned7. China deployed first more than 2,0008 and then more than 3,4009 personnel along the border, and its reports say the fire did not cross the border line. The satellites show no contiguous burned area extending into China, and two burned patches on the Chinese side: about 12 km² in the south section, on the East Ujimqin Banner side, consistent with the backburning operations that the East Ujimqin Banner authorities reported publicly; and about 0.9 km² west of Arxan, which is inferred to be fire that crossed the border by about 1 km and was then stopped by the firebreak that Hinggan League created by counter-burning (对冲点烧, backburning toward the oncoming fire) along the border from 10-11. Smoke reached Hailar on 10-11 and Baicheng on 10-12, and the PM2.5 peaks in the two cities on those days contain smoke from this fire. This post records the accounts from the parties involved, the ignition time and the spread, the weather at the fire area, the burned area, the assessment of burning near the border, and the smoke transport. The confidence in each conclusion is listed at the end. ...

Note The satellite data in this post (Sentinel-1, NISAR and the optical scenes) was retrieved, processed and composited by the author. Claude compiled the text from those processed results and from public news reporting. Processing parameters and acquisition times are taken from the data itself; the event description and casualty figures come from the public sources linked in the text. At 02:52:10 UTC on 2026-08-26 (08:37 Nepal time, 10:52 China time), an ice and rock cliff on the north side of Langtang Lirung collapsed inside Langtang National Park. USGS located the source from seismic waves, on the north face of a peak roughly 7,200 m high; the main event released energy equivalent to M5.2, followed about 3 hours later by a secondary collapse equivalent to M4.2. AntarcticGlaciers gives the detachment coordinates as 28.2853°N, 85.5252°E and states that the present evidence does not support a glacial lake outburst flood (GLOF); the proposed mechanism is a multi-hazard cascade of ice and bedrock failure, rock/ice avalanche and debris flow, temporary river blockage, then outburst flooding. The author describes all of these as preliminary. The debris flow travelled about 100 km down the Bhote Koshi and Trishuli rivers and destroyed the customs facilities at the Rasuwagadhi border crossing along with the China–Nepal highway. The Wikipedia article records, as of 28 August, 547 dead and 977 missing on the Nepali side and 5 dead and 558 missing on the Chinese side; the search is ongoing, sources differ in what they count and when they were updated, and the figures are still changing. The same area saw a large ice and rock avalanche during the 2015 Gorkha earthquake that buried villages in the Langtang valley and killed more than 350 people. This post records the data work done in the two weeks after the event: building the Sentinel-1 pre-event baseline, processing the first obtainable post-event SAR data (NISAR, L-band) and the first post-event Sentinel-1 scene, and then the four viewing geometries that followed. ...