Tsunamis are a scary and devastating natural phenomenon. On average, two damaging tsunamis occur globally each year. A major, devastating, ocean-wide tsunami occurs roughly every 15 years. To prevent catastrophic loss of life, many countries have independently or jointly developed tsunami early warning systems.
To understand how these systems work and how they can fail, it is important to understand the causes of tsunamis. At the most basic, a tsunami is caused by a large, sudden motion on the seafloor. Earthquakes beneath or near the ocean most commonly cause this motion, but other potential causes include volcanic eruptions, underwater landslides, or even an above water landslide, such as a large piece of ice breaking off an iceberg or a meteor striking the ocean.
How Tsunami Early Warning Systems Work?
Since a vast majority of tsunamis are caused by seismic activity on the seafloor, warning systems start with seismic monitoring. Sensors on the seafloor monitor for seismic activity caused by earthquakes and volcanoes. If a substantial seismic incident occurs, surface buoy sensors then monitor for changes in the sea level. Tsunami waves could be as shallow as three feet high, so these sensors are placed in an array to determine motion as well as height. These seafloor and surface buoy sensors send data to tsunami warning centers, which are staffed 24/7. The centers monitor the data, perform analysis, and quickly determine whether conditions are met to issue a tsunami warning alert. If an alert is sent, it goes to local radio and television, wireless emergency alerts, NOAA Weather Radio, and NOAA websites. Some tsunami threat areas might also issue warnings through sirens, text message alerts, and phone notifications.
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