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As early as 426 BC the Greek historian Thucydides inquired in his book History of the Peloponnesian War about the causes of tsunami, and was the first to argue that ocean earthquakes must be the cause. [12] [13] The oldest human record of a tsunami dates back to 479 BC, in the Greek colony of Potidaea, thought to be triggered by an earthquake.
In seismology, a tsunami earthquake is an earthquake which triggers a tsunami of significantly greater magnitude, as measured by shorter-period seismic waves. The term was introduced by Japanese seismologist Hiroo Kanamori in 1972. [1] Such events are a result of relatively slow rupture velocities. They are particularly dangerous as a large ...
A volcanic tsunami, also called a volcanogenic tsunami, is a tsunami produced by volcanic phenomena. About 20–25% of all fatalities at volcanoes during the past 250 years have been caused by volcanic tsunamis. The most devastating volcanic tsunami in recorded history was that produced by the 1883 eruption of Krakatoa.
As word of the eruption spread, government agencies on surrounding islands and in places as far away as New Zealand, Japan and even the U.S. West Coast issued tsunami warnings.
A seismogram recorded in Massachusetts, United States. The magnitude 9.1 (M w) undersea megathrust earthquake occurred on 11 March 2011 at 14:46 JST (05:46 UTC) in the north-western Pacific Ocean at a relatively shallow depth of 32 km (20 mi), [9] [56] with its epicenter approximately 72 km (45 mi) east of the Oshika Peninsula of Tōhoku, Japan, lasting approximately six minutes.
West Coast surfers might snicker at the cause, but the National Weather Service confirms the rare 4-foot (1.2 meter) wave was caused by a kind of tsunami, just not the kind you usually hear about.
Normal tsunamis result from displacement of the sea floor due to movements in the Earth's crust (plate tectonics). Powerful earthquakes may cause the sea floor to displace vertically on the order of tens of metres, which in turn displaces the water column above and leads to the formation of a tsunami.
Researchers have concluded there is a “rare but real risk” that an earthquake-produced tsunami could inundate parts of coastal Anchorage under certain conditions, a newspaper reported, a shift ...