Editing Tsunami (section)

==Warnings and predictions==
{{See also|Tsunami warning system}}{{More citations needed|Section|date=July 2023}}
[[File:Calculated Travel Time Map for 1964 Alaska Tsunami.jpg |thumb|upright=1.35|Calculated travel time map for the [[1964 Alaska earthquake#Tsunami|1964 Alaska tsunami]] (in hours)]]

Drawbacks can serve as a brief warning. People who observe drawback (many survivors report an accompanying sucking sound) can survive only if they immediately run for high ground or seek the upper floors of nearby buildings.

In 2004, ten-year-old [[Tilly Smith]] of [[Surrey]], England, was on [[Maikhao beach]] in [[Phuket Province|Phuket]], Thailand with her parents and sister, and having learned about tsunamis recently in school, told her family that a tsunami might be imminent. Her parents warned others minutes before the wave arrived, saving dozens of lives. She credited her geography teacher, Andrew Kearney.

In the [[2004 Indian Ocean earthquake|2004 Indian Ocean tsunami]] drawback was not reported on the African coast or any other east-facing coasts that it reached. This was because the initial wave moved downwards on the eastern side of the [[Megathrust earthquake|megathrust]] and upwards on the western side. The western pulse hit coastal Africa and other western areas.

A tsunami cannot be precisely predicted, even if the magnitude and location of an earthquake is known. [[Geologist]]s, [[oceanographer]]s, and [[seismologist]]s analyse each earthquake and based on many factors may or may not issue a tsunami warning. However, there are some warning signs of an impending tsunami, and automated systems can provide warnings immediately after an earthquake in time to save lives. One of the most successful systems uses bottom pressure sensors, attached to buoys, which constantly monitor the pressure of the overlying water column.

Regions with a high tsunami risk typically use [[tsunami warning system]]s to warn the population before the wave reaches land. On the west coast of the United States, which is prone to tsunamis from the Pacific Ocean, warning signs indicate evacuation routes. In Japan, the populace is well-educated about earthquakes and tsunamis, and along Japanese shorelines, tsunami warning signs remind people of the natural hazards along with a network of warning sirens, typically at the top of the cliffs of surrounding hills.<ref name="Chanson_2010">{{cite journal|author=Chanson, H.|author-link=Hubert Chanson|title=Tsunami Warning Signs on the Enshu Coast of Japan|url=http://espace.library.uq.edu.au/view/UQ:203103|journal=Shore & Beach|pages=52–54|number=1|volume=78|date=2010|issn=0037-4237}}</ref>

The [[Pacific Tsunami Warning Center|Pacific Tsunami Warning System]] is based in [[Honolulu]], [[Hawaii|Hawai{{okina}}i]]. It monitors Pacific Ocean seismic activity. A sufficiently large earthquake magnitude and other information triggers a tsunami warning. While the subduction zones around the Pacific are seismically active, not all earthquakes generate a tsunami. Computers assist in analysing the tsunami risk of every earthquake that occurs in the Pacific Ocean and the adjoining land masses.

<gallery mode="packed" heights="120px">
File:Bamfield Tsunami Hazard Zone sign.jpg|Tsunami hazard sign at [[Bamfield]], [[British Columbia]]
File: A tsunami warning sign in Kamakura, Japan.jpg|A tsunami warning sign in [[Kamakura, Kanagawa|Kamakura]], Japan
File:Zona de Inundabilidad.jpg|A Tsunami hazard sign (Spanish – English) in [[Iquique]], Chile
File:Tsunami Evacuation Route signage south of Aberdeen Washington.jpg|alt=Photo of evacuation sign|Tsunami Evacuation Route signage along [[U.S. Route 101 in Washington|U.S. Route 101]], in [[Washington (state)|Washington]]
</gallery>

As a direct result of the Indian Ocean tsunami, a re-appraisal of the tsunami threat for all coastal areas is being undertaken by national governments and the United Nations Disaster Mitigation Committee. A tsunami warning system is being installed in the Indian Ocean.

[[File:Dart tsunamicover.jpg|thumb|upright|One of the deep water [[buoy]]s used in the [[Deep-ocean Assessment and Reporting of Tsunamis|DART]] tsunami warning system]]

[[Computer model]]s can predict tsunami arrival, usually within minutes of the arrival time. Bottom pressure sensors can relay information in [[present|real time]]. Based on these pressure readings and other seismic information and the seafloor's shape ([[bathymetry]]) and coastal [[topography]], the models estimate the amplitude and surge height of the approaching tsunami. All [[Pacific Rim]] countries collaborate in the Tsunami Warning System and most regularly practise evacuation and other procedures. In Japan, such preparation is mandatory for government, local authorities, emergency services and the population.

Along the United States west coast, in addition to sirens, warnings are sent on television and radio via the [[National Weather Service]], using the [[Emergency Alert System]].

===Possible animal reaction===
{{further|Infrasound#Animal reaction}}
Some zoologists hypothesise that some animal species have an ability to sense subsonic [[Rayleigh wave]]s from an earthquake or a tsunami. If correct, monitoring their behaviour could provide advance warning of earthquakes and tsunamis. However, the evidence is controversial and is not widely accepted. There are unsubstantiated claims about the [[1755 Lisbon earthquake|Lisbon quake]] that some animals escaped to higher ground, while many other animals in the same areas drowned. The phenomenon was also noted by media sources in [[Sri Lanka]] in the [[2004 Indian Ocean earthquake]].<ref>{{cite news|publisher=BBC|date=2005-03-27|first=Helen|last=Lambourne|title=Tsunami: Anatomy of a disaster|url=http://news.bbc.co.uk/1/hi/world/south_asia/4269847.stm}}</ref><ref>{{cite magazine|title=Surviving the Tsunami: What Sri Lanka's animals knew that humans didn't|first=Christine|last=Kenneally|author-link=Christine Kenneally|magazine=[[Slate (magazine)|Slate Magazine]]|url=http://www.slate.com/id/2111608|date=2004-12-30}}</ref> It is possible that certain animals (e.g., [[elephant]]s) may have heard the sounds of the tsunami as it approached the coast. The elephants' reaction was to move away from the approaching noise. By contrast, some humans went to the shore to investigate and many drowned as a result.