(CNN) -- Here is some background information about tsunamis.
Tsunamis are formed by a displacement of water - a landslide, volcanic eruption, or slippage of the boundary between two of the earth's tectonic plates - slabs of rock 50 to 650 feet (15 to 200 km) thick that carry the Earth's continents and seas on an underground ocean of much hotter, semi-solid material.
Tsunamis can travel up to 600 mph (965 k/ph, 521 knots) at the deepest point of the water, but slow as they near the shore, eventually hitting the shore at 30 to 40 mph (48 to 64 k/ph, 26 to 35 knots). The energy of the wave's speed is transferred to height and sheer force as it nears shore.
Major or Notable Tsunamis: November 1, 1755 - An estimated 60,000 people are killed when an earthquake strikes Lisbon, Portugal, and causes a tsunami.
August 27, 1883 - An estimated 36,000 people are killed when the Krakatau volcano erupts causing a tsunami in the Indonesian islands of Java and Sumatra.
June 15, 1896 - An estimated 28,000 people are killed when an 8.5 magnitude earthquake strikes Sanriku, Japan, causing a tsunami.
December 28, 1908 - An estimated 70,000 - 100,000 people are killed when a 7.2 magnitude earthquake strikes Messina, Italy, and causes a tsunami in the Straights of Messina.
May 22, 1960 - An estimated 1,500 people are killed when a magnitude 9.5 earthquake strikes Chile and causes a tsunami.
March 28, 1964 - An estimated 128 people are killed when a magnitude 9.2 earthquake strikes Prince William Sound, Alaska, and causes a tsunami.
August 16, 1976 - An estimated 4,000 - 8,000 people are killed when a magnitude earthquake 8.0 strikes the Philippines and causes a tsunami.
July 17, 1998 - An estimated 2,200 people are killed when a magnitude 7.0 earthquake strikes Papua New Guinea and causes a tsunami.
December 26, 2004 - An estimated 227,898 people are killed when a 9.1 magnitude earthquake strikes near Sumatra, Indonesia, and causes a subsequent tsunami in 14 countries in South Asia and East Africa.
October 25, 2010 - An estimated 449 people are killed when a magnitude 7.7 earthquake strikes Indonesia and causes a tsunami.
March 11, 2011 - A magnitude 9.0 earthquake off the coast of Japan causes a major tsunami in Japan. The confirmed death toll is 15,887 as of July 10, 2014.