Whenever a big earthquake strikes like the one that occurred in Indonesia on April 11th, 2012, it raises fears of a tsunami which is one of the world's deadliest natural phenomena. Fortunately, the April 11th earthquake did not trigger a devastati...
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Indonesia Earthquake - Why No Tsunami? - as part of the news and politics series by GeoBeats. Whenever a big earthquake strikes like the one that occurred in Indonesia on April 11th, 2012, it raises fears of a tsunami which is one of the world's deadliest natural phenomena. Fortunately, the April 11th earthquake did not trigger a devastating tsunami. So why can some major earthquakes lead to tsunamis but not others? Let's start with defining a tsunami, which is essentially a series of ocean waves caused due to a sudden motion under the sea. Earthquakes can lead to tsunami when the shifting in tectonic plates is more vertical in nature- a vertical rise or drop of the sea floor is what results in waves. And the extent of movement primarily determines the size of waves. Greg Valentine, a geology professor from the University of Buffalo, in an interview with Scientific American described how tsunami waves were triggered after the earthquake in Japan on March 11th, 2011. "And then it will suddenly snap, where the Pacific plate will go down very suddenly and the Asian plate that Japan is part of will sort of bounce up a little bit. The sudden motion of those two plates displaces a huge volume of water, and that's what causes the tsunami." When the earthquakes are caused by horizontal movement, a tsunami is less likely to happen. And according to the New York Times, that's why experts believed the strong earthquake in Indonesia on April 11th did not lead to a tsunami. “Since the motion is horizontal, it is not moving the water column, it is less likely to produce a destructive tsunami,” explains Bruce Pressgrave, a geophysicist. Ever wonder where the name tsunami came from? It's a Japanese word which literally means 'harbor wave', which is not an accurate representation of the phenomenon but that's how we call it around the world. Also, other than earthquakes, landslides, volcanic eruptions and even objects from outer space like meteors and asteroids can trigger tsunami waves.

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