On March 11, 2011, a magnitude (Mw) 9.1 earthquake struck off the northeast coast of Honshu on the Japan Trench. A tsunami that was generated by the earthquake arrived at the coast within 30 minutes, overtopping seawalls and disabling three nuclear reactors within days. The 2011 Tohoku Earthquake and Tsunami event, often referred to as the Great East Japan earthquake and tsunami, resulted in over 18,000 dead, including several thousand victims who were never recovered.
The deadly earthquake was the largest magnitude ever recorded in Japan and the third-largest in the world since 1900.
How It Happened
The 2011 event resulted from thrust faulting on the subduction zone plate boundary between the Pacific and North America plates, according to the U.S. Geological Survey.
This region has a high rate of seismic activity, with the potential to generate tsunamis. Past earthquakes that generated tsunamis in the region have included the deadly events of 1611, 1896, and 1933.
The March 11, 2011, earthquake generated a tsunami with a maximum wave height of almost 40 meters (130 feet) in the Iwate Prefecture. Researchers also determined that a 2,000-kilometer (1,242-mile) stretch of Japan’s Pacific coast was impacted by the tsunami.
Following the earthquake, a tsunami disabled the power supply and cooling of three Fukushima Daiichi reactors, causing a significant nuclear accident. All three nuclear cores largely melted in the first three days.
As of December 2020, the Japan National Police Agency reported 15,899 deaths, 2,527 missing and presumed deaths, and 6,157 injuries for the Great East Japan event.
In Japan, the event resulted in the total destruction of more than 123,000 houses and damage to almost a million more. Ninety-eight percent of the damage was attributed to the tsunami. The costs resulting from the earthquake and tsunami in Japan alone were estimated at $220 billion USD. The damage makes the 2011 Great East Japan earthquake and tsunami the most expensive natural disaster in history.
Although the majority of the tsunami’s impact was in Japan, the event was truly global. The tsunami was observed at coastal sea level gauges in over 25 Pacific Rim countries, in Antarctica, and on the west coast of the Atlantic Ocean in Brazil.
The tsunami caused $31 million USD damage in Hawaii and $55 million USD to marine facilities in California. Additionally, damage was reported in French Polynesia, Galapagos Islands, Peru, and Chile.
Fortunately, the loss of life outside of Japan was minimal (one death in Indonesia and one death in California) due to the Pacific Tsunami Warning System and its connections to national-level warning and evacuation systems.
From Peril to Preparedness
To learn from the tragedy in Japan, researchers collected extensive data on tsunami wave forces and building performance. This facilitated improvement in tsunami mitigation strategies, such as building codes. Over 6,200 tsunami wave measurements were collected in Japan and the Pacific region.
Several thousands of lives across the world were lost to large, far-afield tsunamis prior to the establishment of the Pacific Tsunami Warning System in 1965. The Great East Japan earthquake and tsunami demonstrated that despite the severity of the natural hazard the investment in the warning system has been a success.
Japan is often considered the country most prepared for tsunamis but still lost numerous lives in this event. Nonetheless, experts believe many lives were saved in Japan and elsewhere due to the existing warning and mitigation systems.
An effective tsunami warning system relies on the free and open exchange and long-term management of global data and science products to mitigate, model, and forecast tsunamis. NCEI is the global data and information service for tsunamis. Global historical tsunami data, including more information about the Great East Japan earthquake and tsunami, are available via interactive maps and a variety of web services.
For more information on how you can prepare for a tsunami, visit the National Tsunami Hazard Mitigation Program. Also, visit NCEI’s Natural Hazards website for more earthquake and tsunami data, images, and educational materials.
Kong, L., P. Dunbar, and N. Arcos (2015). Pacific Tsunami Warning System: A Half-Century of Protecting the Pacific 1965-2015. Honolulu: International Tsunami Information Center.
Satake, K. (2014). Chapter 24, The 2011 Tohoku, Japan, Earthquake and Tsunami. Extreme Natural Hazards, Disaster Risks and Societal Implications, Cambridge University Press, p. 340-351.
UNESCO/IOC (2012). Summary Statement from the Japan - UNESCO - UNU Symposium on The Great East Japan Tsunami on 11 March 2011 and Tsunami Warning Systems: Policy Perspectives 16 - 17 February 2012