Tsunami caused by the earthquake.

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In summary, an earthquake creates a tsunami, which is just like any other wave. The tsunami is smaller closer to the earthquake, and coasts further away have less of an effect.
  • #1
MatSci
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I was reading in the newspaper and saw that it said that there was first an initial tidal wave, then the water receded for 10 minutes, then the big wave came crashing ashore. I was just trying to think on why the water would recede for so long, being 10 minutes. When the earthquake takes place how exactly does it effect the water? Does it first give an outward push causing the small wave then cave back in causing the water to recede and all of the water that receded rush back outward?
 
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  • #2
MatSci said:
I was reading in the newspaper and saw that it said that there was first an initial tidal wave, then the water receded for 10 minutes, then the big wave came crashing ashore. I was just trying to think on why the water would recede for so long, being 10 minutes. When the earthquake takes place how exactly does it effect the water? Does it first give an outward push causing the small wave then cave back in causing the water to recede and all of the water that receded rush back outward?

I actually thought this through in the first instance of when I seen the first report, early (uk) boxing day morning. The BBC report showed a graphic image of Tsunami, shoreline's close to the epicentre would experience a rapid tidal receeding effect.

This was caused by the ocean 'welling' upwards over the earthquake area, enough to cause closeby tides to receed, but coastlines that were far away had no receeding effect.

At least that is how I read the early reports?
 
  • #3
Anyone can answer this? Or maybe send some sites on how earthquakes form tsunamis?
 
  • #4
Wow, I heard that on the news, but thought nothing of it, that's REALLY interesting... ohh I just thought of an explination:
( http://en.wikipedia.org/wiki/Image:2004_Indonesia_Tsunami.gif )
Many waves of varying heights were produced by the 9.0 earthquake, as shown in the computer generation taken from NOAA.
 
  • #5
Wave's_Hand_Particle said:
This was caused by the ocean 'welling' upwards over the earthquake area, enough to cause closeby tides to receed, but coastlines that were far away had no receeding effect.

At least that is how I read the early reports?
That "welling up" is the tsunami itself - and since the tsunami is just like any other wave, it has a trough like any other wave - and both propagate together. Its less noticeable (and much, much smaller, of course) but every ocean wave works exacly the same way. When you're at the beach and see the water pulled toward a coming wave, it really is being pulled toward the coming wave - its not just that the previous wave is receeding.

Coastlines further away had less of a receeding effet because the tsunami was much smaller further away.
 
  • #7
Nice links Tom, thanks.
 

What is a tsunami?

A tsunami is a series of large waves caused by a disturbance in the ocean, such as an earthquake, volcanic eruption, or landslide.

How does an earthquake cause a tsunami?

When an earthquake occurs on the ocean floor, it causes a sudden shift in the seafloor, which displaces a large amount of water. This displacement creates a series of waves that radiate outwards from the source of the earthquake.

How fast can a tsunami travel?

The speed of a tsunami depends on the depth of the water and the size of the wave, but they can reach speeds of up to 500 miles per hour in the open ocean. As the waves reach shallower water near the coast, they slow down and increase in height.

How far can a tsunami reach inland?

The distance a tsunami can reach inland depends on the size and strength of the wave, as well as the topography and elevation of the land. In some cases, tsunamis have been known to travel miles inland and cause significant damage.

How can we predict when a tsunami will occur?

While we cannot predict exactly when an earthquake will happen, there are warning signs that can indicate the potential for a tsunami, such as strong and long-lasting earthquakes, changes in sea level, and loud ocean noises. Governments also have warning systems in place to monitor seismic activity and issue alerts in the event of a potential tsunami.

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