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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Megatsunami | 8/10 | https://en.wikipedia.org/wiki/Megatsunami | reference | science, encyclopedia | 2026-05-05T07:35:36.838495+00:00 | kb-cron |
==== 2020: Elliot Creek, British Columbia, Canada ==== On 28 November 2020, unseasonably heavy rainfall triggered a landslide of 18,000,000 m3 (24,000,000 cu yd) into a glacial lake at the head of Elliot Creek. The sudden displacement of water generated a 100 m (330 ft) high megatsunami that cascaded down Elliot Creek and the Southgate River to the head of Bute Inlet, covering a total distance of over 60 km (37 mi). The event generated a magnitude 5.0 earthquake and destroyed over 8.5 km (5.3 mi) of salmon habitat along Elliot Creek. The slope had been gradually weakened over time by the retreat of West Grenville Glacier, causing the weight distribution in this area to change.
==== 2023: Dickson Fjord, Greenland ====
On 16 September 2023 a large landslide originating 300–400 m (980–1,310 ft) above sea level entered Dickson Fjord, triggering a tsunami exceeding 200 m (660 ft) in run-up. Run-up of 60 m (200 ft) was observed along a 10 km (6.2 mi) stretch of coast. There was no major damage and there were no casualties. The tsunami was followed by a seiche that lasted for a week. The seiche produced a nine-day disturbance recorded by seismic instruments globally.
==== 2025: Tracy Arm, Alaska ==== On 10 August 2025, a large landslide consisting of approximately 100,000,000 m3 (130,000,000 cu yd) of material occurred near the terminus of South Sawyer Glacier in Tracy Arm, a fjord in Southeast Alaska. A 470-to-500-metre (1,542-to-1,640-foot) run-up occurred on the shore of Tracy Arm opposite the landslide and a run-up of at least 30 metres (98 ft) took place at nearby Sawyer Island in Tracy Arm. At the mouth of Tracy Arm, waves estimated at 3 to 5 metres (10 to 15 ft) in height struck Harbour Island, where water rose at least 25 feet (7.6 m) above the high tide line. Tsunami waves of up to 36 centimetres (14 in) reached a gauge 80 miles (129 km) from the landslide at Juneau, Alaska. According to the Alaska Earthquake Center, the event had a magnitude of Mw 5.4.
== Potential future megatsunamis == In a BBC television documentary broadcast in 2000, experts said that they thought that a landslide on a volcanic ocean island is the most likely future cause of a megatsunami. The size and power of a wave generated by such means could produce devastating effects, travelling across oceans and inundating up to 25 kilometres (16 mi) inland from the coast. This research was later found to be flawed. The documentary was produced before the experts' scientific paper was published and before responses were given by other geologists. There have been megatsunamis in the past, and future megatsunamis are possible but current geological consensus is that these are only local. A megatsunami in the Canary Islands would diminish to a normal tsunami by the time it reached the continents. Also, the current consensus for La Palma is that the region conjectured to collapse is too small and too geologically stable to do so in the next 10,000 years, although there is evidence for past megatsunamis local to the Canary Islands thousands of years ago. Similar remarks apply to the suggestion of a megatsunami in Hawaii.
=== British Columbia === Some geologists consider an unstable rock face at Mount Breakenridge, above the north end of the giant fresh-water fjord of Harrison Lake in the Fraser Valley of southwestern British Columbia, Canada, to be unstable enough to collapse into the lake, generating a megatsunami that might destroy the town of Harrison Hot Springs (located at its south end).
=== Canary Islands ===