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Disaster Risk Reduction

Sky-High Perspective

Using JAXA’s precision

satellite technology to assess natural disasters

Earth observation satellites are dedicated to disaster monitoring, environmental monitoring and resource surveying. Japan has launched three of these probes so far, mainly for land observation: FUYO-1 (April 1992 to October 1998), DAICHI (April 2006 to April 2011), and DAICHI-2 (launched in June 2014).
The advantage of seeing Earth from a satellite is the capability to survey a wide region all at once. Obtaining overviews of the areas the 2011 Great East Japan Earthquake hit would have been impossible without satellites. And since satellites orbit the globe, they can scan the same region repeatedly and monitor it for changes.
The state-of-the-art DAICHI-2 specializes in radar observations using radio waves bounced off the planet’s surface for greatly improved accuracy. (The previous two craft were equipped with optical cameras.) “It performed so well that we were able to confirm, for example, which highways had collapsed due to the earthquake,” says Kenichi Toda, head of the Disaster Management Support Systems Office at the Satellite Applications and Promotion Center of the Japan Aerospace Exploration Agency (JAXA).
Earthquakes and other disasters don’t happen only during the daytime in clear weather. The advantage of radar observation is that it can monitor the Earth even at night or in cloudy conditions. Furthermore, radio waves use the low frequencies of the L-band, which is unique to Japan’s earth observation satellites. They can penetrate grass and trees to directly assess the Earth’s surface. Since forests cover extensive areas of Japan, JAXA took the early initiative in developing technology suited to the country’s topology and made its use practical.
So what specific roles can Earth observation satellites play after a calamity strikes? The top priority at the time of a natural disaster is gaining an accurate understanding of the damage. When the Great East Japan Earthquake hit, for example, the DAICHI satellite in service at that time instantaneously took images of disaster areas and then sent them down. Personnel used the images to immediately determine which areas the tsunami had flooded, and to what degree, as well as which expanses of the sea were choked with debris and how badly. The images helped enable swift responses by relief and restoration personnel and prevented secondary disasters. Reconstruction after a great disaster can take months and even years, and satellites can also check areas at fixed intervals and give officials a better grasp of how the recovery effort is progressing, which aids in more focused planning.
JAXA has cooperative agreements with disaster prevention agencies such as the Cabinet Office (Disaster Management) to use its satellites for disaster support. When JAXA receives requests from government agencies and local governments for more information on a certain area, the agency makes rapid, precise observations via the DAICHI-2 and provides data.
JAXA’s cooperative efforts don’t stop at Japan’s borders, either. The International Charter on Space and Major Disasters—an international agreement among space and disaster prevention agencies around the globe— calls on its members to use their own satellites to make observations and then provide the data to disaster prevention agencies of the countries affected. Sentinel Asia, a similar framework proposed by Japan, is also working in the Asia-Pacific region, which is particularly prone to storm and flood damage.
Regarding future challenges, Toda says, “Our efforts thus far have primarily focused on post-disaster support. Even though we’ve assisted in creating hazard maps, I can’t say we’ve made a sufficient contribution on the issue of preventing damage. I’d like to beef up our prevention functions, such as our ability to predict and notice subtle changes in terrain through systematic observation, and the ability to forecast volcanic eruptions and sudden landslides.”


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