In its most general sense, the word earthquake is used to describe any seismic event — whether natural or caused by humans — that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults, but also by other events such as volcanic activity, landslides, mine blasts, and nuclear tests. An earthquake's point of initial rupture is called its focus or hypocenter. The epicenter is the point at ground level directly above the hypocenter
TSUMANI A tsunami (plural: tsunamis or tsunami; from Japanese:lit. "harbour wave"; English pronunciation: /suːˈnɑːmi/ soo-nah-mee or /tsuːˈnɑːmi/tsoo-nah-mee) is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake.Earthquakes, volcanic eruptions and other underwater explosions (including detonations of underwater nuclear devices), landslides, glacier calvings,meteorite impacts and other disturbances above or below water all have the potential to generate a tsunami.
Tsunami waves do not resemble normal sea waves, because their wavelength is far longer. Rather than appearing as a breaking wave, a tsunami may instead initially resemble a rapidly rising tide, and for this reason they are often referred to as tidal waves. Tsunamis generally consist of a series of waves with periods ranging from minutes to hours, arriving in a so-called "wave train". Wave heights of tens of metres can be generated by large events. Although the impact of tsunamis is limited to coastal areas, their destructive power can be enormous and they can affect entire ocean basins; the 2004 Indian Ocean tsunami was among the deadliest natural disasters in human history with over 230,000 people killed in 14 countries bordering the Indian Ocean.
The Greek historian Thucydides suggested in 426 BC that tsunamis were related to submarine...
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