40 Millions de Mètres Cubes | Le Jour où une Montagne a Traversé la Vallée

In central Switzerland, a mountainside is constantly monitored by sensors. Below it lie one of the country's major railway hubs, on the Gotthard axis, a highway, and a village of several thousand inhabitants. All rest on the same debris field. And beneath this debris field lie 457 people. On September 2, 1806, in the late afternoon, a section of the Rossberg broke away from the summit of the Gnipen. In about three minutes, nearly 40 million cubic meters of rock buried the villages of Goldau and Röthen, and then a branch of the flow sent a 15-meter wave crashing into Lake Lauerz. It was the greatest natural disaster in Swiss history. This documentary tells the story of why this mountain had been destined to fall for 25 million years, what the inhabitants saw coming for weeks without believing it, and what actually happened that day. Then comes the aftermath, which is just as important as the tragedy itself: how a peaceful lake was transformed into a weapon, how this tragedy simultaneously gave rise to Swiss national solidarity and the modern science of landslides—and why, two centuries later, the mountain remains under surveillance, while the Gotthard Base Tunnel railway and the highway run over its dead. ─────────────────────────────── TIMESTAMPS 0:00 — The mountain under sensors, and 457 missing under the debris 0:44 — September 2, 1806: forty million cubic meters 1:56 — Twenty-five million years: a predestined mountain 2:53 — The mechanism: marl, this slippery slip surface 4:36 — The ignored signs (1804-1806) 5:34 — Why no one left 6:11 — September 2, hour by hour 7:05 — A thousand meters of elevation change in three minutes 7:54 — The lake rises like a wall: the Lauerzersee wave 9:28 — The toll: 457 dead, 102 homes destroyed, 14 survivors 10:48 — A few minutes' delay between the living and the dead 11:14 — The first collection from all the cantons 12:27 — The birth of landslide science 13:36 — Reconstruction, and the village rebuilt on its ruins 14:13 — The railway: Arth-Goldau, a Gotthard hub on the scree cone 15:31 — The mountain has never been declared harmless 15:58 — The Gribsch, 2005: the largest landslide since 1806 17:02 — Coda: from Goldau to Blatten, memory and the sensors ───────────────────────────── LOCATION Goldau and Röthen — municipality of Arth, canton of Schwyz The Rossberg and its western summit, the Gnipen (1567 m) — Molasse massif Lake Lauerz, island of Schwanau, village of Seewen Arth-Goldau station — node of the Gotthard axis, built on the scree field of 1806 ────────────────────────────── SOURCES Historical Dictionary of Switzerland (HLS-DHS-DSS) — hls-dhs-dss.ch Federal Office of Topography — swisstopo WSL Federal Institute — Natural Hazards Research Canton of Schwyz — Office for Forests and Nature, Hazard Maps — sz.ch Swiss Alpine Club (SAC) and Swiss National Museum Bussmann & Anselmetti (2010), Swiss Journal of Geosciences — Lauerzersee wave Thuro, Berner & Eberhardt (2005) — mechanism Breakthroughs Switzerland State Archives and Zurich University of the Arts Library — archives and period works SRF and RTS — Archives ────────────────────────────── THE SUNDAY BRIEF Every Sunday: Switzerland's infrastructure and secrets, revealed. Subscribe so you don't miss the next episodes. A like and a share help this work reach its audience. This documentary is also available as an audiobook, perfect for listening on your commute or while walking. Find "The Sunday Brief" on all major podcast platforms. Website and newsletter: swissculturedigest.ch Instagram, LinkedIn: @swissculturedigest This documentary draws on public sources, archives, and period works in the public domain. The maps and diagrams were created for narrative purposes. © 2026 Swiss Culture Digest — www.swissculturedigest.ch