Geologists have unraveled the mystery of “failed” tsunami
How is it that one underwater landslide leads to destructive wave, and another, similarly large, hardly causes a ripple in the ocean? In the Norwegian geotechnical Institute in Oslo tried to explain this mystery.
More than 8,000 years ago, Storegga series of major landslides, was off the coast of Norway, — provoked catastrophe.
Landslides occurred under the water at the edge of the continental shelf 100 km Northwest of As-og modern County of møre og Romsdal, Norway. The event caused a major tsunami in the Northern part of the Atlantic ocean and captured a length of about 290 km of the coast, amounted to about 3,500 km3 (such number of breeds could cover the Iceland layer 34 m).
It is curious that an event like catastrophic landslide, repeated after 4500 years, but destructive waves have arisen, reports New Scientist.
To find out why these two landslide has led to such different results, Finn Lilholt from the Norwegian geotechnical Institute in Oslo and his colleagues have developed computer models of two types of landslides and compared them with the potential of creating tsunamis.
The first model, the so-called regression bias arises in the lower part of the slope and forms a cascade (stacked) landslide. The second model is constructed as a regressive shift, but moving faster down the slope and “covers” sediment almost completely.
Storegga, landslides can cause a tsunami if underwater slopes turn into fast-moving debris with a volume of 3000 km3. Other landslides do not become catastrophic due to the fact that precipitation is shifted in parts, none of which can cause destruction.
Until now it was thought that tsunami almost impossible to avoid, in the case of underwater landslides. It is now known that humanity should not so much worry about tsunamigenesis of certain landslides.