Tsunami

tsunamistidal waveseaquaketsunami waveseismic sea wavetidal wavesDrawbackearthquake wavesIndian Ocean Tsunaminamesake
A tsunami (from 津波, "harbour wave"; English pronunciation: or ), sometimes incorrectly referred to as a tidal wave, also known as a seismic sea wave, is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake.wikipedia
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Earthquake

earthquakesseismic activityseismic
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.
When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami.

Submarine earthquake

underseaundersea earthquakeSubmarine
The Ancient Greek historian Thucydides suggested in his 5th century BC History of the Peloponnesian War that tsunamis were related to submarine earthquakes, but the understanding of tsunamis remained slim until the 20th century and much remains unknown.
They are the leading cause of tsunamis.

1755 Lisbon earthquake

1755 earthquakeLisbon earthquakeearthquake
Of historical and current (with regard to risk assumptions) importance are the 1755 Lisbon earthquake and tsunami (which was caused by the Azores–Gibraltar Transform Fault), the 1783 Calabrian earthquakes, each causing several tens of thousands of deaths and the 1908 Messina earthquake and tsunami.
In combination with subsequent fires and a tsunami, the earthquake almost totally destroyed Lisbon and adjoining areas.

1783 Calabrian earthquakes

earthquake of 1783earthquake1783
Of historical and current (with regard to risk assumptions) importance are the 1755 Lisbon earthquake and tsunami (which was caused by the Azores–Gibraltar Transform Fault), the 1783 Calabrian earthquakes, each causing several tens of thousands of deaths and the 1908 Messina earthquake and tsunami.
The 1783 Calabrian earthquakes were a sequence of five strong earthquakes that hit the region of Calabria in southern Italy (then part of the Kingdom of Naples), the first two of which produced significant tsunamis.

Wind wave

waveswavewave dominated
Unlike normal ocean waves, which are generated by wind, or tides, which are generated by the gravitational pull of the Moon and the Sun, a tsunami is generated by the displacement of water.
Such waves are distinct from tides, caused by the Moon and Sun's gravitational pull, tsunamis that are caused by underwater earthquakes or landslides, and waves generated by underwater explosions or the fall of meteorites—all having far longer wavelengths than wind waves.

Alexandria

Alexandria, EgyptAlexandrianAl-Iskandariyya
The Roman historian Ammianus Marcellinus (Res Gestae 26.10.15–19) described the typical sequence of a tsunami, including an incipient earthquake, the sudden retreat of the sea and a following gigantic wave, after the 365 AD tsunami devastated Alexandria.
On 21 July 365, Alexandria was devastated by a tsunami (365 Crete earthquake), an event annually commemorated years later as a "day of horror".

Slump (geology)

slumpslumpingslumps
However, like tsunami, seismic sea wave is not a completely accurate term, as forces other than earthquakes – including underwater landslides, volcanic eruptions, underwater explosions, land or ice slumping into the ocean, meteorite impacts, and the weather when the atmospheric pressure changes very rapidly – can generate such waves by displacing water.
These submarine slumps can generate disastrous tsunamis.

426 BC Malian Gulf tsunami

426 BCan earthquakean earthquake in 426 BCE
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.
Thucydides inquired into its causes, and concluded that the tsunami must have been caused by an earthquake, He was thus historically the first known to correctly interpret the cause of a tsunami as a preceding geological event.

1960 Valdivia earthquake

Great Chilean earthquakeValdivia earthquake1960
The 1960 Valdivia earthquake (M w 9.5), 1964 Alaska earthquake (M w 9.2), 2004 Indian Ocean earthquake (M w 9.2), and 2011 Tōhoku earthquake (M w 9.0) are recent examples of powerful megathrust earthquakes that generated tsunamis (known as teletsunamis) that can cross entire oceans.
The resulting tsunami affected southern Chile, Hawaii, Japan, the Philippines, eastern New Zealand, southeast Australia and the Aleutian Islands.

1964 Alaska earthquake

Good Friday earthquake1964 earthquakeGreat Alaska earthquake
The 1960 Valdivia earthquake (M w 9.5), 1964 Alaska earthquake (M w 9.2), 2004 Indian Ocean earthquake (M w 9.2), and 2011 Tōhoku earthquake (M w 9.0) are recent examples of powerful megathrust earthquakes that generated tsunamis (known as teletsunamis) that can cross entire oceans.
The 1964 Alaskan earthquake, also known as the Great Alaskan earthquake and Good Friday earthquake, occurred at 5:36 PM AKST on Good Friday, March 27. Across south-central Alaska, ground fissures, collapsing structures, and tsunamis resulting from the earthquake caused about 139 deaths.

2004 Indian Ocean earthquake and tsunami

2004 Indian Ocean earthquake2004 Indian Ocean tsunami2004 tsunami
The 1960 Valdivia earthquake (M w 9.5), 1964 Alaska earthquake (M w 9.2), 2004 Indian Ocean earthquake (M w 9.2), and 2011 Tōhoku earthquake (M w 9.0) are recent examples of powerful megathrust earthquakes that generated tsunamis (known as teletsunamis) that can cross entire oceans. The 2004 Indian Ocean tsunami was among the deadliest natural disasters in human history, with at least 230,000 people killed or missing in 14 countries bordering the Indian Ocean.
A series of large tsunamis up to 30 m high were created by the underwater seismic activity that became known collectively as the Boxing Day tsunamis. Communities along the surrounding coasts of the Indian Ocean were seriously affected, and the tsunamis killed an estimated 227,898 people in 14 countries.

Teletsunami

ocean-wide tsunamiteletsunamis
The 1960 Valdivia earthquake (M w 9.5), 1964 Alaska earthquake (M w 9.2), 2004 Indian Ocean earthquake (M w 9.2), and 2011 Tōhoku earthquake (M w 9.0) are recent examples of powerful megathrust earthquakes that generated tsunamis (known as teletsunamis) that can cross entire oceans.
A teletsunami (also called an ocean-wide tsunami, distant tsunami, distant-source tsunami, far-field tsunami, or trans-ocean tsunami) is a tsunami that originates from a distant source, defined as more than 1,000 km away or three hours' travel from the area of interest, sometimes travelling across an ocean.

2011 Tōhoku earthquake and tsunami

2011 Tōhoku earthquakeTōhoku earthquake and tsunami2011 Tohoku earthquake and tsunami
The 1960 Valdivia earthquake (M w 9.5), 1964 Alaska earthquake (M w 9.2), 2004 Indian Ocean earthquake (M w 9.2), and 2011 Tōhoku earthquake (M w 9.0) are recent examples of powerful megathrust earthquakes that generated tsunamis (known as teletsunamis) that can cross entire oceans.
The earthquake triggered powerful tsunami waves that may have reached heights of up to 40.5 m in Miyako in Tōhoku's Iwate Prefecture, and which, in the Sendai area, traveled up to 10 km inland.

365 Crete earthquake

365 tsunamiAn earthquakeearthquake
The Roman historian Ammianus Marcellinus (Res Gestae 26.10.15–19) described the typical sequence of a tsunami, including an incipient earthquake, the sudden retreat of the sea and a following gigantic wave, after the 365 AD tsunami devastated Alexandria.
The Crete earthquake was followed by a tsunami which devastated the southern and eastern coasts of the Mediterranean, particularly Libya, Alexandria and the Nile Delta, killing thousands and hurling ships 3 km inland.

Landslide

landslideslandslipdebris avalanche
However, like tsunami, seismic sea wave is not a completely accurate term, as forces other than earthquakes – including underwater landslides, volcanic eruptions, underwater explosions, land or ice slumping into the ocean, meteorite impacts, and the weather when the atmospheric pressure changes very rapidly – can generate such waves by displacing water.
Landslides that occur undersea, or have impact into water e.g. significant rockfall or volcanic collapse into the sea, can generate tsunamis.

1908 Messina earthquake

Messina earthquakeearthquake of 19081908
Of historical and current (with regard to risk assumptions) importance are the 1755 Lisbon earthquake and tsunami (which was caused by the Azores–Gibraltar Transform Fault), the 1783 Calabrian earthquakes, each causing several tens of thousands of deaths and the 1908 Messina earthquake and tsunami.
About ten minutes after the earthquake, the sea on both sides of the Strait suddenly withdrew as a 12-meter (39-foot) tsunami swept in, and three waves struck nearby coasts.

Megatsunami

mega-tsunamimegatsunamislandslide tsunami
Scientists named these waves megatsunamis.
Megatsunamis have quite different features from other, more usual types of tsunamis.

1933 Sanriku earthquake

19331933 Sanriku1933 Showa Sanriku earthquake
Movement on normal (extensional) faults can also cause displacement of the seabed, but only the largest of such events (typically related to flexure in the outer trench swell) cause enough displacement to give rise to a significant tsunami, such as the 1977 Sumba and 1933 Sanriku events.
The associated tsunami caused widespread damage.

Hilo, Hawaii

HiloHilo, HINAS Hilo
On April 1, 1946, the 8.6 Aleutian Islands earthquake occurred with a maximum Mercalli intensity of VI (Strong). It generated a tsunami which inundated Hilo on the island of Hawaii with a 14 m surge.
On April 1, 1946, a 7.8-magnitude earthquake near the Aleutian Islands created a 14 m tsunami that hit Hilo 4.9 hours later, killing 160 people.

Wave shoaling

shoalingshoaling wavespitch up and break
They grow in height when they reach shallower water, in a wave shoaling process described below.
This is particularly evident for tsunamis as they wax in height when approaching a coastline, with devastating results.

1946 Aleutian Islands earthquake

Aleutian Islands earthquake1946 tsunamitsunami
On April 1, 1946, the 8.6 Aleutian Islands earthquake occurred with a maximum Mercalli intensity of VI (Strong). It generated a tsunami which inundated Hilo on the island of Hawaii with a 14 m surge.
The seafloor along the fault was elevated, triggering a Pacific-wide tsunami with multiple destructive waves at heights ranging from 45–130 ft. The tsunami obliterated the Scotch Cap Lighthouse on Unimak Island, Alaska among others, and killed all five lighthouse keepers.

Storm surge

storm tidetidal surgestorm surges
Meteotsunamis should not be confused with storm surges, which are local increases in sea level associated with the low barometric pressure of passing tropical cyclones, nor should they be confused with setup, the temporary local raising of sea level caused by strong on-shore winds.
A storm surge, storm flood or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low pressure weather systems (such as tropical cyclones and strong extratropical cyclones), the severity of which is affected by the shallowness and orientation of the water body relative to storm path, as well as the timing of tides.

Megathrust earthquake

megathrustmegathrust typemegathrust earthquakes
The 1960 Valdivia earthquake (M w 9.5), 1964 Alaska earthquake (M w 9.2), 2004 Indian Ocean earthquake (M w 9.2), and 2011 Tōhoku earthquake (M w 9.0) are recent examples of powerful megathrust earthquakes that generated tsunamis (known as teletsunamis) that can cross entire oceans.
Since these earthquakes deform the ocean floor, they often generate a significant series of tsunami waves.

Hawaii

State of HawaiiHIHawaiian Islands
Susceptible locations are believed to be the Big Island of Hawaii, Fogo in the Cape Verde Islands, La Reunion in the Indian Ocean, and Cumbre Vieja on the island of La Palma in the Canary Islands; along with other volcanic ocean islands.
On the flanks of the volcanoes, slope instability has generated damaging earthquakes and related tsunamis, particularly in 1868 and 1975.

1977 Sumba earthquake

1977 Sumba1977-08-19August 19, 1977
Movement on normal (extensional) faults can also cause displacement of the seabed, but only the largest of such events (typically related to flexure in the outer trench swell) cause enough displacement to give rise to a significant tsunami, such as the 1977 Sumba and 1933 Sanriku events.
The shock occurred near the southern section of the Sunda Trench where several other tsunami-generating earthquakes have occurred.