My heart goes out to the people of Japan as they clean up and rebuild following the devastating earthquake and tsunami. The earthquake struck with almost no warning, and reports indicate that tsunami waves as high as 33 feet in some areas reached Japan’s northeast shores within 30 minutes of the 8.9 magnitude quake. Many of us have seen the incredible videos that show waves of water and debris tragically washing away homes, businesses, and schools, and tossing cars, ships, and planes as if they were toys.
Because the Japanese tsunami formed close to shore and traveled to land quickly, there was simply not adequate time to evacuate everyone from such a large area before the waves hit the coast. Similar conditions prevailed in the Indian Ocean tsunami of 2004 with the added problem that people were not well educated about the warning signs and dangers of a tsunami. It was widely reported that many people in Sumatra and other areas even rushed towards the receding waves to gather fish from the sea floor.
Japan is among the most prepared of all nations for earthquakes and tsunamis. A relatively high percentage of its buildings are engineered to withstand earthquakes with shock absorber-like features that give buildings flexibility to move with seismic waves instead of collapsing. Japan has lined about 40% of its coastlines with concrete seawalls, breakwaters or other structures meant to protect the country against high waves and typhoons, or even tsunamis.
But perhaps the single most important survival factor of all is that Japan’s people are well educated from a young age on how to respond to both earthquakes and tsunamis. This is likely the reason that, despite significant losses of human life, even more lives were not lost, given that 30-foot high waves swept over an area with about 1 million people, and pushed more than 2-miles inland. Many of the people knew what to do.
Past tsunamis have cost lives and property in many coastal areas of the United States including Hawaii, Alaska, Puerto Rico, American Samoa, the Virgin Islands, California, and Oregon, but there have been relatively few fatalities from tsunamis compared to more common disasters such as floods, hurricanes, and tornadoes. Because devastating tsunamis are relatively infrequent in the United States, it is more difficult to sustain awareness and preparedness.
However, the devastating effects of the Indian Ocean tsunami—an estimated 240,000 dead and many villages washed away—prompted U.S. legislation in 2005 to improve the U.S. tsunami forecasting systems. In addition, Congress asked the National Research Council to review tsunami detection and warning networks and to identify ways the country could become more prepared for tsunamis. The resulting expert report, Tsunami Warning and Preparedness, was released in July 2010.
The report concludes that the U.S. tsunami detection systems have generally improved since 2004. The United States has two Tsunami Warning Centers, located in Hawaii and Alaska. These centers are in charge of monitoring seismic activity and collecting data from DART (Deep-ocean Assessment and Reporting of Tsunamis) buoys, which are placed at intervals in the Pacific Ocean. These buoys monitor changes in the water pressure on the ocean floor to detect the passage of a tsunami. The National Oceanic and Atmospheric Administration has made significant progress in expanding the DART network, manufacturing and deploying an array of 39 buoys, establishing 16 new coastal sea level gauges, and upgrading 33 existing water level monitoring stations.
Based on analysis of these data, the Tsunami Warning Centers issue alerts to the appropriate emergency managers. Information collected from sea-level sensors generates forecasts of tsunami wave heights, which are then used to adjust or cancel warnings, watches, and advisories. These data also reveal tsunamis from sources that do not generate seismic waves, such as sea floor landslides.
DART system information is useful and important for distant coastlines. However, for nearby shorelines, tsunami warnings must be issued in minutes based on seismic information available immediately after the earthquakes. The fact is that many U.S. coastal regions that could experience earthquakes near their shores as was the case in Japan. In particular those communities along the “ring of fire” including Alaska, Hawaii, and the West coast still face major challenges in responding to the threats of near-shore tsunamis. Even if a tsunami warning is issued quickly, there is simply not enough time to for emergency managers to disseminate the warning message and order an evacuation.
Therefore, the report concludes that no matter how good tsunami detection systems becomes, surviving a tsunami generated close to shore depends mostly on the ability of people to recognize the warning signs and to immediately head for high ground. People need to be able to recognize natural cues such as the shaking of the ground from the tsunami-generating earthquake, and, as seen in the Indian Ocean tsunami, receding of ocean waters, and immediately know what to do without official warnings or evacuation instructions. Therefore, education and outreach are important components for U.S. tsunami preparedness in order to minimize deaths and injuries. For a lengthier summary of the report’s findings, click here to read the four-page report in brief.
The United States and other nations can learn from Japan. With an effort to educate the public about the warning signs of tsunamis, future losses can be minimized.