As this happens the leading edge of the top plate snags on the bottom plate and pressure starts to build. Eventually the pressure becomes too much and the pressure is released in the form of an earthquake. This type of earthquake is called a megathrust earthquake which is the most powerful type of earthquake.
When these megathrust earthquakes occur under water large amount of water is displaced and a tsunami wave occurs. Tsunami Wave Normal waves occur as a result of friction between wind and sea and only affect the surface area. When tsunamis occur a shock wave is sent throughout the full depth of the ocean and this has a number of different affects.
Tsunami waves are very small in the open ocean, measuring only one or two meters, and only manifest themselves as they approach the shallower seas of the coastline. As a tsunami reaches the coastline they start to slow down as the bottom of the wave comes in contact with shallower sea bed.
The top of the wave however continues at a high speed and as a result the wave stacks up on itself and becomes higher and higher before eventually falling over itself and breaking onto the coastline. Destruction There are normally two phases of destruction when a tsunami hits, the first as the wave crashes onto coastal areas and the second as the water from the wave pulls back into the sea bringing with is large amounts of debris from the land.
Tsunamis can range in size from 1 or two metres to Mega-tsunamis hundreds of metres high. Mega-tsunamis Most mega-tsunamis are caused by major landslides falling into bodies of water. The largest tsunami ever recorded was in Lituya Bay, Alaska and measured metres tall and was as a result of a massive landslide falling into Lituya Bay. Share Tweet Email. Read This Next Wild parakeets have taken a liking to London. Animals Wild Cities Wild parakeets have taken a liking to London Love them or hate them, there's no denying their growing numbers have added an explosion of color to the city's streets.
India bets its energy future on solar—in ways both small and big. Environment Planet Possible India bets its energy future on solar—in ways both small and big Grassroots efforts are bringing solar panels to rural villages without electricity, while massive solar arrays are being built across the country. Epic floods leave South Sudanese to face disease and starvation. Travel 5 pandemic tech innovations that will change travel forever These digital innovations will make your next trip safer and more efficient.
But will they invade your privacy? Go Further. Animals Wild Cities This wild African cat has adapted to life in a big city. Animals This frog mysteriously re-evolved a full set of teeth.
Animals Wild Cities Wild parakeets have taken a liking to London. Animals Wild Cities Morocco has 3 million stray dogs. Meet the people trying to help. Animals Whales eat three times more than previously thought. Environment Planet Possible India bets its energy future on solar—in ways both small and big.
Environment As the EU targets emissions cuts, this country has a coal problem. Paid Content How Hong Kong protects its sea sanctuaries. History Magazine These 3,year-old giants watched over the cemeteries of Sardinia. Magazine How one image captures 21 hours of a volcanic eruption. See the percentages on the right for the geological events that cause tsunamis. A disturbance that displaces a large water mass from its equilibrium position can cause a tsunami.
In order to understand the role of violent seafloor movement as a major cause of tsunamis, one needs to understand plate tectonics.
They move relative to each other at rates of up to several inches per year. A plate boundary is the area where two plates come into contact.
The way one plate moves relative to another determines the type of boundary: spreading, where the two plates move away from each other; subduction, where the two plates move toward each other, with one sliding beneath the other; and transform, where the two plates slide horizontally past each other. Subduction is the main cause of major tsunami events. There are subduction zones with associated deep-sea trenches off Chile, Alaska, Japan, and Indonesia, for example, that have produced large earthquakes and devastating tsunamis, many of which caused damage and loss of life in the Hawaiian Islands.
0コメント