Six months after Kumamoto Prefecture and its neighboring areas were hit by a series of powerful earthquakes, support for people who lost their homes in the deadly temblors remains an ongoing challenge. The Kumamoto quakes serve as yet another reminder that we need to think hard about how to bolster defenses against quakes to minimize the damage they cause.

Last month, the national government started its review of the Law on Special Measures Concerning Countermeasures for Large-Scale Earthquakes, which is based on the assumption that a Tokai earthquake — a major temblor long forecast to hit Shizuoka Prefecture and its adjacent areas — is predictable. But instead of expending a large amount of effort and resources on a goal that may be impossible to attain — it is still very difficult to predict quakes — the government should focus on strengthening defenses against powerful temblors.

A key lesson highlighted by the Kumamoto quakes was the vulnerability of houses and buildings that are located on or close to an active fault. In the town of Mashiki, which, along with the village of Nishihara, registered temblors of the maximum 7 on the Japanese scale of seismic intensity, most of the badly damaged houses were built directly on active faults in the Futagawa fault zone, where the quakes were focused.

According to a recent NHK report that examined more than 20,000 disaster certificates issued by the Mashiki and Nishihara municipal offices, some 3,500 buildings lying within 500 meters of active faults were destroyed — or about 66 percent of the structures that were recognized as having entirely collapsed. Nearly 80 percent of the destroyed buildings in Mashiki were concentrated in areas within 1 km of active faults. It was the same pattern of damage that was seen in other quakes that struck on active faults, such as the 1995 Great Hanshin Earthquake that devastated Kobe and its environs, killing more than 6,000 people and destroying 105,000 homes and buildings.

Given that Japan has some 2,000 active faults, local authorities nationwide should take a cue from the Kumamoto quakes and review their policies on land used for housing and public facilities in areas with active faults.

A law enacted in the wake of the 2011 Great East Japan Earthquake and tsunami empowers local governments to restrict housing development and construction in areas identified with a high tsunami risk. Although it is very difficult to predict when earthquakes will strike, it is possible to identify high-risk areas that contain active faults or are vulnerable to tsunami. Therefore similar measures should be considered for land use in areas with active faults. For example, a by-law introduced in 2012 by Tokushima Prefecture to beef up defenses against big earthquakes calls for “optimizing” land use in areas containing active faults of the Median Tectonic Line, which stretches from Kanto to Kyushu via Shikoku, and urges parties concerned to refrain from building public facilities for use by large numbers of people or structures for storing dangerous materials on active faults. Authorities in all areas with active faults should consider initiatives that can help residents avoid living in close proximity to them.

In the Kumamoto quakes, deaths by indirect causes — such as health problem caused or exacerbated by a protracted evacuation — outnumbered the 50 fatalities caused by structural collapses. As happened in many other major disasters, this underlines the need to take sufficient measures to ease the stress of disaster victims and to ensure they have adequate medical care. Many evacuees with disabilities also faced various problems in public shelters that were not designed to accommodate such people. The relevant authorities should review whether the public facilities that they’ve earmarked for use as evacuation shelters can adequately serve all residents.

The Kumamoto quakes have also led the authorities to review the way disaster-related information is publicly announced. The magnitude-6.5 temblor on the evening of April 14, which registered 7 on the Japanese intensity scale, led the Meteorological Agency to warn there was a “20 percent chance” of an “aftershock” with an intensity of 6 or higher within three days. But the second big temblor turned out to be even bigger — a magnitude-7.3 quake that hit in the early hours of April 16. The agency came under fire, with critics saying that its initial warning gave the impression that subsequent temblors would be smaller than the first one, prompting some people to stay in their houses — only to be crushed when their houses collapsed in the bigger quake. The agency has since decided not to use the term “aftershock” in warnings and instead will urge people in disaster areas to brace for more temblors of similar intensities.

Similarly, the agency will now grade the risk of major quakes on large faults instead of using raw probability figures. Prior to the Kumamoto quakes, the probability of a big quake happening along the Futagawa fault (which shifted in the April temblors) within 30 years was put “between roughly zero to 0.9 percent” and was rated as “rather high,” but the figure itself carried a risk of misleading people that the chance was small. Under the agency’s new grading method, that figure would translate into the “A rank” — the second-highest grade.

Such improvements are welcome, but they shouldn’t stop there. The ways of informing the public about disaster risks should be constantly reviewed and revamped with the aim of providing information that will allow people to take the most effective defensive measures against quakes and other natural disasters.

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