Tsunami warning system facts for kids
A tsunami warning system (often called TWS) helps find tsunamis early. It sends out warnings to keep people safe and protect buildings. This system has two main parts: special sensors that detect tsunamis and a way to quickly send out alarms. This allows people in coastal areas to move to safety. There are two types of tsunami warning systems: international (for large areas) and regional (for smaller, local areas). When an earthquake happens, alerts are sent out. Then, data from sea level sensors (like tide gauges or special buoys called DART buoys) confirm if a tsunami is coming.
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How Tsunami Warnings Started
The very first simple system to warn about tsunamis was tried in Hawaii in the 1920s. Better systems were created after big tsunamis hit in 1946 and 1960. These tsunamis caused a lot of damage in Hilo, Hawaii.
Tsunamis travel very fast in the open ocean, between 500 and 1,000 kilometers per hour. But earthquake waves travel even faster, around 14,400 kilometers per hour. This speed difference gives scientists time to figure out if a tsunami might happen. Then, they can send warnings to places that might be in danger. Sometimes, these systems give warnings even when a big tsunami doesn't happen. This is because it's hard to know exactly which earthquakes will cause huge tsunami waves.
International Tsunami Warning Systems
These systems cover large parts of the world's oceans.
Pacific Ocean System
For most of the Pacific Ocean, tsunami warnings come from the Pacific Tsunami Warning Center (PTWC). This center is run by the United States NOAA in Ewa Beach, Hawaii. Another center, the National Tsunami Warning Center (NTWC) in Palmer, Alaska, sends warnings for North America. This includes places like Alaska, California, and the East Coast.
The PTWC started in 1949 after a tsunami in 1946 caused many deaths. The NTWC began in 1967. Different countries work together through a group set up by UNESCO to make sure these warnings reach everyone. In 2017, the U.S. government decided to keep funding this important global system.
Chile's Warning System
In 2005, Chile began building a system called IPOC. It's a network of 14 stations that watch for earthquakes along a 600-kilometer stretch of coastline. Each station has special tools like seismometers and GPS antennas. Some stations are even buried underground. These tools work with tide gauges to help detect tsunamis.
After the big 2010 Maule earthquake in Chile, these sensors picked up signals. Similar signals were seen after the 2004 Indian Ocean tsunami. Studies show that these tools are very helpful for watching for tsunamis. In 2010, some sensors even showed a signal about 20 minutes before the tsunami reached the coast.
Indian Ocean Warning System
After the terrible 2004 Indian Ocean earthquake and tsunami that killed almost 250,000 people, the United Nations decided to create an Indian Ocean Tsunami Warning System. This system helps Indonesia and other affected areas. However, Indonesia's system stopped working in 2012 because its detection buoys broke down. This means tsunami warnings there now mostly rely on detecting earthquakes. They cannot predict tsunamis caused by volcanoes.
Indonesia was hit by tsunamis again in 2018. The one in December 2018 was caused by a volcano.
Warning System for Europe and Mediterranean
A group called ICG/NEAMTWS was formed in 2005 by UNESCO. This group works to set up a tsunami early warning system for the North Eastern Atlantic, the Mediterranean Sea, and connected waters. Many countries and organizations attended the first meeting in Rome to plan this important system.
Caribbean Warning System
Countries in the Caribbean planned to have their own tsunami warning system by 2010. They met in Panama City in 2008 to discuss it. Panama had a major tsunami in 1882 that killed many people. Barbados even tested its tsunami plan in 2010 as a trial for the region.
Regional Tsunami Warning Systems
Regional or local warning centers use earthquake data from nearby areas. They quickly figure out if there's a possible local tsunami threat. These systems can send warnings to people using public address systems and sirens in less than 15 minutes.
Even though they can quickly calculate where an underwater earthquake happened and when a tsunami might arrive, it's hard to know if the ground shifts underwater will cause big waves. This means these systems can sometimes give false alarms. But because these warnings are for small, local areas, a false alarm doesn't cause much trouble. Real tsunamis would affect a much larger area.
Japan's Warning System
Japan has a warning system that covers the whole country. It usually sends a tsunami warning just minutes after an Earthquake Early Warning (EEW) is issued. During the 2011 Tōhoku earthquake and tsunami, a "major tsunami" warning was sent within 3 minutes. This meant waves were expected to be at least 3 meters (9.8 feet) high. After the 2011 disaster, Japan improved its system in 2013 to better predict tsunamis.
India's Warning System
India has one of the most advanced tsunami warning systems in the world. After the 2004 tsunami, the Indian government set up the Indian National Centre for Ocean Information Services (INCOIS). This center provides ocean information and advice for things like tsunami warnings and ocean forecasts.
INCOIS gets data from over 35 sea level gauges every 5 minutes. It also uses data from wave buoys, special underwater pressure readers, and a network of earthquake sensors. The Indian Tsunami Buoy System uses buoys on the surface and pressure readers on the ocean floor. They communicate with each other and send readings to shore using satellites. The warning station also gathers information from many earthquake stations in India and over 300 international stations.
INDOFOS is a service that predicts the state of the Indian Ocean. These forecasts are shared through information centers, radio, digital signs, websites, and TV. India also uses the Oceansat 2 satellite system to monitor the ocean. This satellite helped predict and lessen the effects of Cyclone Phailin in 2013.
How Warnings Are Sent Out
Finding and predicting tsunamis is only part of the job. It's just as important to warn people in the affected areas. All tsunami warning systems use many ways to communicate. These include Cell Broadcast, SMS (text messages), e-mail, fax, and radio. They often use strong, dedicated systems to send emergency messages to emergency services and the military. They also use systems like sirens and the Emergency Alert System to warn the public.
Challenges of Tsunami Warnings
Because tsunami waves travel so fast in open water, no system can protect against a very sudden tsunami. This happens when the coast is very close to where the earthquake occurred. For example, a devastating tsunami hit off the coast of Hokkaidō in Japan in 1993. It struck just three to five minutes after the earthquake. Many people on the small island of Okushiri, Hokkaido died because they were caught while trying to escape to higher ground. The same thing happened in Aceh, Indonesia.
Even with these challenges, warning systems can be very helpful. For instance, if a very large earthquake happened off the west coast of the United States, people in Japan would have more than 12 hours before any tsunami arrived. They would also get warnings from systems in Hawaii and other places. This would give them time to leave areas that might be affected.
See also
In Spanish: Alerta de tsunami para niños
- Deep-ocean Assessment and Reporting of Tsunamis (DART)
- Disaster risk reduction
- Pacific Disaster Center
- Sound Fixing and Ranging (SOFAR) channel
