Japan Tsunami Warning System 2011: How it Worked and Its Effectiveness

Japan has one of the most advanced tsunami warning systems worldwide. The 2011 tsunami has proven how effective this system was. The Japan Tsunami Warning System 2011 helped the countries minimize the death toll and the number of missing people during the disaster.

However, the 2011 tsunami was destructive. Therefore, the wave killed thousands of people despite the dissemination of the 2011 Japan tsunami alert via various communication channels. After the tragedy, the government evaluated the system and published a comprehensive report on the 2011 tsunami.

What Happened in March 2011?

March 11, 2011, was a gloomy day for many people in Japan, especially those living on the northeastern coast of Honshu. That afternoon, a massive earthquake shook the country. About an hour after the Great Sendai Earthquake, a tsunami swept Honshu’s northeastern coast.

This tsunami destroyed many areas in different prefectures, such as Iwate, Miyagi, and Fukushima. According to the record, the height of the wave reached 12 m at Sendai Airport. Meanwhile, the inundation height in many areas was 3 to 4 m.

The 2011 tsunami caused more than 19,700 people dead, over 2,500 people missing, and about 6,200 people injured. The wave also caused a nuclear accident in Fukushima.

An Overview of the Japan Tsunami Warning System 2011

The 2011 Japan Tsunami Warning System could distribute a timely warning to those living in Fukushima, Iwate, and Miyagi. People in those areas got the tsunami warning about 3 minutes after the quake. 

The warning said a major tsunami of at least 3 m would reach the coastline of Japan in 10 to 30 minutes. Therefore, people had enough time to get away from coastal areas. 

1. Components of Japan Tsunami Warning System

The Japan Tsunami 2011 Early Warning System consists of several components.

• Sensors: This system uses several sensors to detect and monitor tsunamis and earthquakes. They are GPS buoys, seismometers, ocean-bottom tsunami sensors, and coastal-area tsunami meters.

• Communication Systems: Communication methods and channels in this system are satellite communications, broadcasters, radio stations, TV channels, and sirens. They are for communicating data from sensors to authorities or warnings from authorities to people.

• Local Notification Methods: Besides those communication channels, authorities notify the locals about a tsunami using different methods. They are trucks with loudspeakers, bells, transmitters, and receivers.

• How the Japan Tsunami Warning System Worked

The 2011 Tsunami Warning System in Japan worked in several steps. 

• The seismometers detected tremors of an earthquake. After that, the sensors calculated the magnitude and hypocenter of this earthquake. 

• Buoys and ocean-bottom tsunami sensors detected changes in the seawater level. 

• The tsunami warning center got data from the earthquake and tsunami sensors via satellite. Moreover, the system in this center used the data to predict tsunami heights and arrival at Japan’s coastal areas.

• Japan Meteorological Agency disseminated warnings via the Internet, radio stations, and TV channels. JMA also broadcasted the warnings to mobile phone users in the affected areas.

• How Effective is the Japan Tsunami Warning System in 2011?

The Japan Tsunami Warning System 2011 was effective and efficient. The system broadcasted a tsunami warning quickly after the earthquake. Moreover, the warning was correct about the tsunami warning category.

However, the warning provided inaccurate information on the height of the wave because the inundation in some areas was higher than in other areas. Despite the effectiveness of this warning system, the country could not avoid a high death toll because of several reasons.

According to reports, 58% of people in Fukushima, Miyagi, and Iwate immediately went to higher grounds after noticing the warning. However, 5% of them went to areas that were not high enough. 

Therefore, the tsunami swept them away. Meanwhile, 42% of people in those three prefectures did not immediately notice the warning. Almost half of them were hit by the killer wave.

4. Tsunami Warning Categories

Tsunami warnings in Japan have three categories. What are they?

• Major Tsunami Warning (purple): This warning indicates a huge killer wave ranging from 3 to over 10 m in height. This huge tsunami can destroy wooden structures and catch people in its current. 

• Tsunami Warning (red): JMA will announce this warning if the wave is 1 to 3 m tall. This tsunami can damage low-lying areas. Moreover, it will flood buildings and catch people in its current.

• Tsunami advisory (yellow): This warning implies a one-meter tsunami. This wave can overturn boats and small vessels and cause danger to people in coastal areas.

The Japan Tsunami Warning System 2011 was effective in alerting people in the affected areas. Moreover, the message or information in this warning was mostly accurate. Thanks to this system, the country could minimize the death toll and the number of casualties and missing people.