How strong does an earthquake have to be to cause a tsunami?

Answer 1

It varies. The size of the quake is only one factor. Others are the shape of the sea floor between the quake and the land, the distance from the shore, the depth, and a dozen other things.

New Answer: All of the above is very true, but many seismologists believe an earthquake of at least 6.0 magnitude is required to generate a tsunami, but of course not all earthquakes above this magnitude will generate a tsunami, even if they occur under the ocean. However, it is mainly a factor of the amount of displacement in the ocean crust as a result of the earthquake, rather than the amount of energy is released by it, as this is what causes the tsunami wave.

New Answer 2: Seafloor movement is only one means in which an earthquake can generate a tsunami; a relatively minor earthquake (or even no earthquake) can trigger a massive landslide on a steep, already-teetering slope, and the tallest recorded tsunami in history were generated by landslides (such as the wave caused by the landslide triggered by the May 18, 1980 eruption of Mount St. Helens into Spirit Lake, estimated to have triggered a wave that reached some 1,500 feet in height; a similar tsunami at over 1,700 feet was triggered by a landslide not even associated with an earthquake nor volcano in Alaska on July 9, 1958. A tsunami could also be generated by a meteor striking the ocean or a lake.

Answer 2

An earthquake should at least measure 6.0 and above on the Richter scale to cause a tsunami. However, that also depends on the located which the earthquakes occur. If it occurs very near the Coastlines, a moderately strong earthquake (5.0+) can cause a relatively destructive tsunami. However, if it occurs far out at sea, an earthquake measuring at least 8.0 and above is able to cause a tsunami, as earthquakes which are not strong will not produce waves that have enough power to reach the shores. These earthquakes will produce waves that are able to sustain the power for many hours before the reach shore. Mega earthquakes (measuring 9.0 and above on the Richter Scale) are said to produce Megatsunamis (also known as Iminami) which are much more destructive than normal tsunamis. They can reach heights of up to 300-500+ metres, and reach about 25 km inland! They are said to be able to cross the Atlantic (Transatlantic).

Answer 3

It just depends...

The thing is that the earthquake it self does not make, create or form the tsunami.

In order for the tsunami to form, the quake need to create changes in the crust of earth.

These changes can be a massive crack in the crust where one part either sinks down or moves up or both on different sides, even the sides moving apart by several meters. This often happen during earthquakes just not at those magnitudes. (Often measure able by satellite to be a few centimeters, less than an inch.)

What is thought to be the main cause of tsunamis is a great rock slide under water caused by an earthquake, but an earthquake does not have to be the cause of this. It will most often result in a tremble though, something that can be measured as an earthquake.

A huge rock slide or mudslide will cause a massive underwater motion of water. when this motion of water moves towards shallow water, it will form massive waves known as tsunamis. Waves of water with a huge content of energy that is unleashed on land.

It is a misconception that only an earthquake can form this, but an earthquake is most often the final drop of energy needed in order to set things in motion.

I would think that in an area of no steep underwater hills where rock slides can occur, an earthquake would need to be in the magnitude of 8 or greater on Richter's scale in order to create a tsunami. Nothing that happens very often at all.

Answer 4

Generally it takes an earthquake of over 7 or 7.5 to cause a tsunami. But it also depends on the seafloor topography.

http://www.livescience.com/8824-earthquakes-tsunamis.html

Answer 5

It does not matter how high magnitude is on the Richter scale the earthquake is, but it matters where the tectonic plates shifted.. in this is case; it would be in the ocean.

Answer 6

how

Answer 7

cute

Answer 8

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