- Tsunami warning system
A tsunami warning system is a system to detect
tsunami s and issue warnings to prevent loss of life and property. It consists of two equally important components: a network of sensors to detect tsunamis and a communications infrastructure to issue timely alarms to permit evacuation of coastal areas.There are two distinct types: international tsunami warning systems, and regional warning systems. Both depend on the fact that, while tsunamis travel at between 500 and 1,000 km/h (around 0.14 and 0.28 km/s) in open water, earthquakes can be detected almost at once as
seismic wave s travel with a typical speed of 4 km/s (around 14,400 km/h). This gives time for a possible tsunami forecast to be made and warnings to be issued to threatened areas, if warranted. Unfortunately, until a reliable model is able to predict which earthquakes will produce significant tsunamis, this approach will produce many more false alarms than verified warnings. In the currect operational paradigm, the seismic alerts are used to send out the watches and warnings. Then, data from observed sea level height (either shore based via tide gauges or deep ocean DART buoys) are used to verify the existence of a tsunami. Other systems have been proposed to augment the warning paradigm. For example, it has been suggested that the duration and frequency content of t-wave energy (which is earthquake energy trapped in the ocean SOFAR channel) is indicative of an earthquakes tsunami potential [Salzberg, 2006] . The first rudimentary system to alert communities of an impending tsunami was attempted inHawaii in the 1920s. More advanced systems were developed in the wake of theApril 1 ,1946 andMay 23 ,1960 tsunamis which caused massive devastation inHilo, Hawaii .International warning systems (IWS)
Pacific Ocean
Tsunami warnings for most of the
Pacific Ocean are issued by thePacific Tsunami Warning Center (PTWC), operated by theUnited States 'sNOAA inEwa Beach, Hawaii . NOAA's West Coast/Alaska Tsunami Warning Center (WC/ATWC) inPalmer, Alaska issues warnings for the west coast of North America, including Alaska, Canada, and the western coterminous United States. PTWC was established in 1949, following the 1946Aleutian Island earthquake and a tsunami that resulted in 165 casualties on Hawaii and in Alaska; WC/ATWC was founded in 1967. International coordination is achieved through the International Coordination Group for the Tsunami Warning System in the Pacific, established by theIntergovernmental Oceanographic Commission ofUNESCO . [http://ioc.unesco.org/itsu/]Indian Ocean (ICG/IOTWS)
After the 2004 Indian Ocean Tsunami which killed almost 230,000 people, a
United Nations conference was held in January 2005 inKobe ,Japan , and decided that as an initial step towards anInternational Early Warning Programme , the UN should establish anIndian Ocean Tsunami Warning System .This then resulted in a system of warnings in Indonesia.This will also save the lives and the livelihood of the people.North Eastern Atlantic, the Mediterranean and connected Seas (ICG/NEAMTWS)
The First Session of the Intergovernmental Coordination Group for the Tsunami Early Warning and Mitigation System in the North Eastern Atlantic, the Mediterranean and connected Seas (ICG/NEAMTWS), established by the
Intergovernmental Oceanographic Commission ofUNESCO Assembly during its 23rd Session in June 2005, through Resolution XXIII.14, took place in Rome on 21st and 22nd November, 2005.The Meeting, hosted by the Government of Italy (Italian Ministry of Foreign Affairs and Ministry for Environment and Protection of the Territory), was attended by more than 150 participants from 24 countries, 13 organizations and numerous observers.Regional warning systems
Regional (or local) warning system centres use
seismic data about nearbyearthquakes to determine if there is a possible local threat of a tsunami. Such systems are capable of issuing warnings to the general public (via public address systems and sirens) in less than 15 minutes. Although theepicenter andmoment magnitude of an underwater quake and the probable tsunami arrival times can be quickly calculated, it is almost always impossible to know whether underwater ground shifts have occurred which will result in tsunami waves. As a result, false alarms can occur with these systems, but due to the highly localised nature of these extremely quick warnings, disruption is small.Conveying the warning
Detection and prediction of tsunamis is only half the work of the system. Of equal importance is the ability to warn the populations of the areas that will be affected. All tsunami warning systems feature multiple lines of communications (such as
e-mail ,fax ,radio and telex, often usinghardened dedicated systems) enabling emergency messages to be sent to theemergency service s andarmed forces , as well to population alerting systems (eg sirens).hortcomings
No system can protect against a very sudden tsunami. A devastating tsunami occurred off the coast of
Hokkaidō in Japan as a result of an earthquake onJuly 12 ,1993 . As a result, 202 people on the small island ofOkushiri, Hokkaido lost their lives, and hundreds more were missing or injured. This tsunami struck just three to five minutes after the quake, and most victims were caught while fleeing for higher ground and secure places after surviving the earthquake.While there remains the potential for sudden devastation from a tsunami, warning systems can be effective. For example if there were a very large
subduction zone earthquake (magnitude 9.0) off the west coast of theUnited States , people inJapan , for example, would have more than 12 hours (and likely warnings from warning systems in Hawaii and elsewhere) before any tsunami arrived, giving them some time to evacuate areas likely to be affected.External links
* [http://www.cwarn.org International Tsunami warnings delivered to mobile phones]
* [http://topics.developmentgateway.org/space/highlights/viewHighlight.do~activeHighlightId=103341 Space Applications for Disaster Monitoring]
* [http://www.tsunami.noaa.gov/warning_system_works.html How does the Tsunami Warning System Work?] from the [http://www.tsunami.noaa.gov/ NOAA Tsunami website]
* [http://www.prh.noaa.gov/pr/ptwc/ Pacific Tsunami Warning Center]
* [http://wcatwc.arh.noaa.gov/ West Coast and Alaska Tsunami Warning Center]
* [http://www.ndbc.noaa.gov/Dart/dart.shtml DART]
* [http://www.geocities.com/tvhuangsg Tsunami Detector for Indian Ocean] Web & Mobile application that reports probability of tsunami occurrences from LIVE USGS data.
* [http://www.envirtech.org/envirtech_tsunameter.htm Envirtech Tsunami Warning System, based on real time seafloor observatories measuring seismic waves and sea levels]
* [http://www.ina.in/itws/ Integrated Tsunami Watcher Service] Web & SMS based Free service.
* [http://www.tsunami.noaa.gov/warnings_forecasts.html NOAA Tsunami Warnings and Forecasts]
* [http://www.dews-online.org/ DEWS - Distant Early Warning System for the Indian Ocean Region]
* [http://www.iotws.org/ Indian Ocean Tsunami Warning Center]
* [http://www.jtic.org/ Jakarta Tsunami Information Centre]
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