![SwitzerlandGeneva](https://upload.wikimedia.org/wikipedia/commons/5/50/SwitzerlandGeneva.jpg)
The Tauredunum event (german: Tauredunum-Ereignis) of 563 AD was a
tsunami
A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explo ...
on
Lake Geneva
, image = Lake Geneva by Sentinel-2.jpg
, caption = Satellite image
, image_bathymetry =
, caption_bathymetry =
, location = Switzerland, France
, coords =
, lake_type = Glacial lak ...
(then under the
Frankish
Frankish may refer to:
* Franks, a Germanic tribe and their culture
** Frankish language or its modern descendants, Franconian languages
* Francia, a post-Roman state in France and Germany
* East Francia, the successor state to Francia in Germany ...
territory of the
Kingdom of Orleans), triggered by a massive landslide which caused widespread devastation and loss of life along the lakeshore. According to two contemporary chroniclers, the disaster was caused by the collapse of a mountainside at a place called Tauredunum at the eastern end of Lake Geneva. It caused a great wave to sweep the length of the lake, sweeping away villages on the shoreline and striking the city of
Geneva
Geneva ( ; french: Genève ) frp, Genèva ; german: link=no, Genf ; it, Ginevra ; rm, Genevra is the List of cities in Switzerland, second-most populous city in Switzerland (after Zürich) and the most populous city of Romandy, the French-speaki ...
with such force that it washed over the city walls and killed many of the inhabitants.
A study published in October 2012 suggests that the Tauredunum landslide triggered the collapse of sediments that had accumulated at the point where the River
Rhône
The Rhône ( , ; wae, Rotten ; frp, Rôno ; oc, Ròse ) is a major river in France and Switzerland, rising in the Alps and flowing west and south through Lake Geneva and southeastern France before discharging into the Mediterranean Sea. At Ar ...
flows into Lake Geneva. This caused a huge underwater mudslide that displaced several hundred million cubic metres of sediment, producing a tsunami up to high that reached Geneva within about 70 minutes. There is evidence of four previous mudslides, suggesting that tsunamis may be a recurrent phenomenon on Lake Geneva. It is also speculated that such an event could happen again, with far more severe consequences as more people live within potentially affected areas, and because most people are not accustomed to the idea of tsunamis happening in landlocked bodies of water and are thus unaware of the danger.
Historical accounts
![LakeGenevaVeveyMontreux](https://upload.wikimedia.org/wikipedia/commons/9/96/LakeGenevaVeveyMontreux.jpg)
The event was recorded in some detail by
Gregory of Tours
Gregory of Tours (30 November 538 – 17 November 594 AD) was a Gallo-Roman historian and Bishop of Tours, which made him a leading prelate of the area that had been previously referred to as Gaul by the Romans. He was born Georgius Florenti ...
in his ''History of the Franks''. He wrote:
Marius of Avenches
Marius Aventicensis or, popularly, Marius of Avenches (532 – 31 December 596) was the Bishop of Aventicum (modern Avenches) from 574, remembered for his terse chronicle. After his death in Lausanne, he was venerated in that city as a saint, ...
also described the event in his ''Chronicle'':
Tauredunum's location and tsunami-avalanche risks in the Alps
The location of Tauredunum has long been debated. Among other alternatives, it has been suggested that it was situated near the Bois Noir at
Saint-Maurice or at the foot of the Pic du Blanchard near
Saint-Gingolph Saint-Gingolph is a small town situated on the south bank of Lake Geneva (Lac Léman). It sits at the France–Switzerland border and is administratively divided into Saint-Gingolph, Switzerland, Saint-Gingolph, Valais (Switzerland) and Saint-Gingol ...
. The landslide is now thought to have occurred on the mountain of
Le Grammont
Le Grammont is a mountain in the Chablais Alps, near Le Bouveret in Valais. At 2,172 metres above sea level, it is one of the highest peaks overlooking Lake Geneva. Various trails lead to the summit, mostly from the southern side.
On the way to ...
, near
Les Evouettes at the point where the Rhône empties into Lake Geneva. Such collapses, known as an or , are not uncommon in the Alps; in October 1963, the collapse of the side of
Monte Toc
Monte Toc, nicknamed the walking mountain by locals due to its tendency to experience landslides, is a mountain on the border between Veneto and Friuli-Venezia Giulia in Northern Italy best known for the Vajont Dam, which was built at the mountai ...
in Italy caused of debris to fall into the lake behind the
Vajont Dam
The Vajont Dam (or Vaiont Dam) is a disused dam in northern Italy. It is one of the tallest dams in the world, with a height of . It is in the valley of the Vajont River under Monte Toc, in the municipality of Erto e Casso, north of Venice.
...
, sending a wave of water into the valley that killed up to 2,500 people.
Mountainside collapses have caused similar though smaller lake tsunamis in at least three lakes in Switzerland –
Lake Lucerne
__NOTOC__
Lake Lucerne (german: Vierwaldstättersee, literally "Lake of the four forested settlements" (in English usually translated as ''forest cantons''), french: lac des Quatre-Cantons, it, lago dei Quattro Cantoni) is a lake in central ...
,
Lake Lauerz
__NOTOC__
Lake Lauerz (German: ''Lauerzersee'', old spelling: ''Lowerzer See'') is a lake in the Canton of Schwyz, Switzerland. Geography
Its water area varies between and (depending on water level), a maximum depth of , and a water level elev ...
and
Lake Brienz
Lake Brienz (german: Brienzersee) is a lake just north of the Alps, in the canton of Bern in Switzerland. It has a length of about , a width of and a maximum depth of . Its area is ; the surface is above the sea-level. It is fed, among others, by ...
. The danger is recognised by Switzerland's Federal Office for Civil Protection, which takes the risk of landslide-caused tsunamis into account in its disaster planning. Certain mountains, such as the
Rigi
The Rigi (or ''Mount Rigi''; also known as ''Queen of the Mountains'') is a mountain massif of the Alps, located in Central Switzerland. The whole massif is almost entirely surrounded by the water of three different bodies of water: Lake Lucerne ...
and the
Bürgenstock
The Bürgenstock is a mountain in Switzerland (1,115 m above sea level). It is located partway along the shore of Lake Lucerne. Bürgenstock is also a resort located at 874 m a.s.l. on the same mountain. The lookout point at the summit of the ...
, present more of a risk. It is not uncommon for large boulders to fall off the Bürgenstock into Lake Lucerne, though this presents little risk of a tsunami because of the relatively low amount of energy released in such falls.
Proposed mechanism for tsunami of 563
A study by a team from the
University of Geneva
The University of Geneva (French: ''Université de Genève'') is a public research university located in Geneva, Switzerland. It was founded in 1559 by John Calvin as a theological seminary. It remained focused on theology until the 17th centu ...
, led by Stéphanie Girardclos and Guy Simpson, has found that the tsunami of 563 may not have been directly caused by the landslide, but by the collapse of sediments on the lake bed. The team found a giant fan of
turbidite
A turbidite is the geologic deposit of a turbidity current, which is a type of amalgamation of fluidal and sediment gravity flow responsible for distributing vast amounts of clastic sediment into the deep ocean.
Sequencing
Turbidites were ...
– a mixture of sand and mud deposited by a rapid flow of water – spread across the lake bed. The fan extends in a north-west direction from the Rhône's mouth, where the river's flow has carved a series of canyon-like underwater channels. The deposit is huge, extending over a length of and a width of , with an average depth of and a volume of at least 250 million m³ (8.8 billion ft³). Biological material found in the turbidite enabled it to be dated to between 381 and 612, consistent with the date of the Tauredunum event.
![Lake Geneva - Tauredunum event](https://upload.wikimedia.org/wikipedia/commons/2/2b/Lake_Geneva_-_Tauredunum_event.png)
It is hypothesised that the impact of the Tauredunum landslide destabilised sedimentary deposits at the mouth of the Rhône, causing their collapse and triggering a large tsunami. According to computer simulations, a wave up to high would have been created by the collapse and would have travelled the full length of the lake within 70 minutes of the event. It would have struck
Lausanne
, neighboring_municipalities= Bottens, Bretigny-sur-Morrens, Chavannes-près-Renens, Cheseaux-sur-Lausanne, Crissier, Cugy, Écublens, Épalinges, Évian-les-Bains (FR-74), Froideville, Jouxtens-Mézery, Le Mont-sur-Lausanne, Lugrin (FR-74), ...
within only 15 minutes, where it would have been about high, though the damage there would have been limited as the city stands on a steeply sloping shoreline. Much greater damage would have been caused at Geneva, where the wave would have been about . A wave this high would certainly have been capable of causing the destruction described by the chroniclers. Other towns along the lakeside would also have been hit by the wave, which would have been about high at
Evian-les-Bains, high at
Thonon-les-Bains
Thonon-les-Bains (; frp, Tonon), often simply referred to as Thonon, is a subprefecture of the Haute-Savoie department in the Auvergne-Rhône-Alpes region in Eastern France. In 2018, the commune had a population of 35,241. Thonon-les-Bains is ...
and high at
Nyon
Nyon (; outdated German language, German: or ; outdated Italian language, Italian: , ) is a Municipalities of Switzerland, municipality in Nyon District in the Cantons of Switzerland, canton of Vaud in Switzerland. It is located some 25 kilomet ...
.
It would have travelled at about , giving those on the shoreline little time to flee.
The team also found evidence of four older layers of turbidite, suggesting that such collapses have been a recurrent event since Lake Geneva formed at the end of the
last ice age some 19,000 years ago. It is not yet known how frequently they have occurred – further investigation will be required to answer this question – but researcher Guy Simpson says, "It's certainly happened before and I think that we can expect that it will probably happen again sometime."
Although most people's focus has been on marine tsunamis such as the
2004 Indian Ocean tsunami
An earthquake and a tsunami, known as the Boxing Day Tsunami and, by the scientific community, the Sumatra–Andaman earthquake, occurred at 07:58:53 local time (UTC+7) on 26 December 2004, with an epicentre off the west coast of northern Suma ...
and the
March 2011 tsunami in Japan,
lakeside cities such as Geneva, from the sea, are also at risk. Katrina Kremer notes that the risk of a fresh tsunami still exists, not just in Lake Geneva, but in other mountain lakes as well: "We have recognised that a tsunami risk applies to all lakes that have unstable slopes along the shore."
However, she warns, "the risk is underestimated because most people just do not know that tsunamis can happen in lakes."
The risk is particularly pronounced for the city of Geneva, given its position on low ground at the funnel-shaped end of the lake, which magnifies the effects of a tsunami.
The impact of a new tsunami on the whole of Lake Geneva would be far more severe now than in 563, as over a million people now live along the lake's shores.
References
See also
*
Seiche
A seiche ( ) is a standing wave in an enclosed or partially enclosed body of water. Seiches and seiche-related phenomena have been observed on lakes, reservoirs, swimming pools, bays, harbors, caves and seas. The key requirement for formation o ...
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History of Geneva
Lake Geneva
563
Natural disasters in Switzerland
6th century in Switzerland
6th-century natural disasters
Landslides in Switzerland
0563 Tauredunum