Earthquakes do not merely destroy homes, bridges and roads. They also have the potential to change the very era in which such structures were built.
There are unique characteristics to the massive temblors that have struck and continue to strike Kumamoto and its surrounding areas. According to historian Michifumi Isoda, an associate professor at the International Research Center for Japanese Studies and author of the book "Tensai kara Nihonshi o yominaosu" (Re-evaluating Japanese history through natural disasters), a similar phenomenon took place in Kumamoto in the early Edo Period.
The following is what Isoda has tried to communicate to the public about modern disaster history through newspapers and television appearances in recent days.
The Keicho Sanriku quake struck in the ocean trench off the Sanriku coast in the Tohoku region in 1611, causing disastrous tsunami. There were massive and frequent quakes in Kumamoto and Oita in 1619 -- and in Kumamoto, Ehime, Kagawa and Hiroshima in 1625 -- all caused by shifting faults. A huge quake subsequently hit directly below Odawara, Kanagawa Prefecture, in 1633, causing widespread damage to the Kanto region, including Tokyo (or what was then called Edo).
Old documents left by the feudal domain of Kumamoto, also known as the Higo Domain, hint that strong aftershocks continued long after the 1625 Kumamoto earthquake. One such document says that unless the Tokugawa shogunate gives permission for the creation of a garden to build an evacuation hut, the daimyo -- the feudal lord of the domain -- cannot continue to stay in the castle keep.
Will we repeat what happened back then, starting with a quake and tsunami in the Tohoku region, moving on to temblors in Kumamoto and Oita, then onto earthquakes in the Shikoku and Chugoku regions, and finally, a massive quake in the Kanto region?
We don't have the answer to this question, but what we do know is that we need to take away some lessons from our past. The gist of Isoda's message is that the quake resistance of facilities such as hospitals and schools lying close to fault zones must be reinforced -- and that we must exercise extreme caution when it comes to decisions regarding the operation of the Sendai Nuclear Power Plant in Kyushu's Kagoshima Prefecture and the Ikata Nuclear Power Plant in Shikoku's Ehime Prefecture.
Four hundred years ago, there were a series of massive earthquakes at a time when tides were turning. Or rather, a series of massive earthquakes brought on great change in the times.
"The Kumamoto earthquake was one of the factors that led to the demise of the power held by Kato Kiyomasa, the daimyo of the Kumamoto domain. Forty-eight metric tons of gunpowder that had been stored in Kumamoto Castle exploded in the quake," Isoda explains. "To the Tokugawa shogunate in Edo, an alliance between Kato and the Shimazu clan of the Satsuma domain in Kagoshima had been a great threat. But that threat disappeared.
"Eight years later, the main keep of Edo Castle withstood the massive shaking caused by the Odawara quake, and records show that this prompted then shogun Tokugawa Iemitsu to declare, 'It is the castle keep of the strong.'
"The Odawara Castle collapsed, but that did not bring on attacks from the western regions. The public finally understood that they would be united by the Tokugawa shogunate, and a 250-year period of peace followed. This is the political process that our forebears experienced."
We in the 21st century, too, are no doubt confronting a time of change, as the ground we live on continues to shake. Where are we, and where are we headed?
Says Isoda, "I think this time, too, earthquakes will determine the direction of politics. Another quake recording a level 7 on the Japanese seismic intensity scale will eliminate the possibility of a simultaneous election in the upper and lower chambers of the Diet. And if that's the case, we face the serious prospect that amendments to the Constitution will not be carried out.
"It's as if we are standing atop the shaking earth watching what will happen to constitutional amendment. Another quake may stop the pen trying to rewrite the Constitution. "
The United States has reduced its involvement in international politics, as China and Russia have gained more of a say. Fighting continues in the Middle East, and Europe is enveloped in chaos. Under such circumstances, there is nothing wrong with Japan reviewing its national security policy or deliberating constitutional revisions.
Political scheming over something that may or may not take place several months from now, however, won't necessarily decide what happens. Politics is often impacted by things that are beyond human wisdom and knowledge. (By Takao Yamada, Special Senior Writer)