The Lake That Became a Flood Overnight | Sikkim

How did a remote Himalayan lake unleash a disaster far downstream? Follow the evidence behind the South Lhonak flood in Sikkim on the night of 3–4 October 2023: slope failure, an impact wave, a breached natural barrier and a river carrying more than water. Watch Channeled Scablands:    • The Ice Age Flood That Came Back 100 Times...   Earth's Hidden Hazards:    • Earth’s Hidden Hazards   0:00 The clues in the valley 0:51 A lake above a lived-in valley 2:13 A landscape that was changing 3:42 The chain breaks 5:31 More than a surge of water 7:38 What scientists could reconstruct 9:21 The warning before the event 10:32 From measurements to warnings 12:06 Following the chain downstream Research: Sattar et al. 2025, Science: https://doi.org/10.1126/science.ads2659 Sattar et al. 2021, Geomorphology: https://doi.org/10.1016/j.geomorph.20... Yu et al. 2024: https://doi.org/10.3390/rs16132307 Mohanty et al. 2026: https://doi.org/10.1038/s41598-026-35... ISRO, 4 October 2023: https://www.isro.gov.in/Satellite_stu... SSDMA reports: https://ssdma.nic.in/activities.html Government of Sikkim, preparedness meeting, 10 September 2026: https://www.sikkim.gov.in/media/news-... Visual credits: Teesta/Rangeet, 2017-05-19: Subhrajyoti07, CC BY-SA 4.0. https://upload.wikimedia.org/wikipedi... Chungthang, 2019-10-21: PRATAP CHAKMA, CC BY-SA 4.0. https://upload.wikimedia.org/wikipedi... Rangpo, 2026-02-02: Pinakpani, CC BY 4.0. https://commons.wikimedia.org/?curid=... Dzongu, 2025-04-14: Amitabha Gupta, CC BY 4.0. https://commons.wikimedia.org/?curid=... Lachen monastery, 2025-04-15: Amitabha Gupta, CC BY 4.0. https://commons.wikimedia.org/?curid=... Lachen, 2018-10-30: Tarunsamanta, CC BY-SA 4.0. https://commons.wikimedia.org/?curid=... Lachen road, 2018-08-16: Prabhat114, CC BY-SA 4.0. https://commons.wikimedia.org/?curid=... Lachen bridge, 2010-05-07: Sujay25, CC BY-SA 4.0. https://commons.wikimedia.org/?curid=... Teesta at Mangan, 2018-08-15: Prabhat114, CC BY-SA 4.0. https://commons.wikimedia.org/?curid=... Teesta river Sikkim AJT Johnsingh P1020196.JPG, 2008-05-04: A. J. T. Johnsingh (WWF-India/NCF), CC BY-SA 3.0. https://commons.wikimedia.org/?curid=... Confluence anglers, 2017-04-27: A. J. T. Johnsingh (WWF-India/NCF), CC BY-SA 4.0. https://commons.wikimedia.org/?curid=... Teesta border, 2015-04-13: Shampa Chaturvedi, CC BY-SA 4.0. https://commons.wikimedia.org/?curid=... Lower Teesta, published 1909: J. Claude White (1853-1918), Public domain. https://commons.wikimedia.org/?curid=... Field photos after the October 2023 flood: Praful Rao and Rajeev Rajak; Sattar et al., accepted manuscript, Fig. 6A–F, S37A–F, S38B, S39A–D, S40 Cam2/3/4/6. CC BY 4.0. https://eprints.whiterose.ac.uk/224098/ Landsat false-colour panels (9 June / 15 October 2023): Yu et al. 2024, Fig. 10, CC BY 4.0; Landsat/USGS. https://doi.org/10.3390/rs16132307 Photos/figures cropped, resized and captioned. BY-SA adapted stills remain under their stated BY-SA licences. https://creativecommons.org/licenses/... https://creativecommons.org/licenses/... https://creativecommons.org/licenses/... Music: Cylinder Seven and Cylinder Nine, Chris Zabriskie, Cylinders (2014). Written, performed and produced by Chris Zabriskie; publisher You've Been a Wonderful Laugh Track (ASCAP). CC BY 4.0. Cut, faded and mixed. https://chriszabriskie.com/cylinders/ https://creativecommons.org/licenses/... AI disclosure: synthetic narration and labelled artistic reconstructions are used. Reconstructions and schematics are illustrative, not authentic event footage or calibrated simulations. Contemporary photographs are dated context; field-photo capture days are unspecified. Scientific volume estimates are reconstructions. Prior hazard scenarios did not predict the exact night. Monitoring reports do not guarantee present equipment uptime.