In his collection of essays titled "Sainan Zakko" (rough thoughts on disaster), physicist Torahiko Terada (1878-1935) included this insightful phrase: "People worry rather more about what's in the rice bin for tomorrow than unpredictable tsunami."

Terada wrote these somewhat desperate, biting words in his autumn years, when he was already worn down by his long advocacy for disaster prevention.

Last June, a report released by the Cabinet's Reconstruction Design Council in response to the Great East Japan Earthquake and tsunami warned of a return to rice bin worries -- economic over safety concerns -- after the meltdowns at the Fukushima No. 1 nuclear plant. However, it must be said that "nuclear safety" itself is a dubious proposition.

One major news item last week was the hearings held by the Diet's nuclear disaster investigation committee. One of the issues raised was whether or not Fukushima plant operator Tokyo Electric Power Co. (TEPCO) had requested government permission to abandon the power station after the hydrogen explosions at the No. 1 and 3 reactor buildings and the cooling failure at the No. 2 reactor. Banri Kaieda, minister of economy, trade and industry in those tense days in March 2011, stated that he did indeed receive a call asking permission to evacuate the plant. TEPCO Chairman Tsunehisa Katsumata, however, continues to insist that "this is not true."

The hearings were not the first time differences in government and TEPCO accounts of the disaster have been revealed. Naoto Kan and Yukio Edano, the prime minister and chief Cabinet secretary at the time, respectively, have made the same claim as Kaieda at other investigative committees. TEPCO executives have also maintained that the request was only to evacuate "some of the plant workers, not all."

What surprises the most is not the discrepancy itself, but that the truth about what actually happened at this turning point in the crisis -- when abandoning the plant may very well have meant evacuating all of eastern Japan -- remains obscured.

In Terada's book of essays, he relates the story of a university professor who, after an airplane crashed in the mountains of Kyushu, had all the parts recovered from the crash site sent to him so he could track down the cause of the accident. After studying the wreckage, the professor determined that one broken aileron wire and one missing screw had led to the crash. His investigations led to preventative measures, and Terada hailed it as a victory for the truth.

Now let's look at the inquiries into the nuclear disaster. Was the catastrophe the result of the earthquake or the tsunami? We don't know. We can guess at this and that, but since no one can get close to the reactors because of the radiation, it's impossible to confirm the particulars.

In the case of reactor No. 3, which had a core meltdown, the latest measurements in the shattered reactor building put radiation levels at as much as 160 millisievert per hour. Even wearing protective gear, a worker in that environment for 25 hours would absorb a dose of 4,000 millisieverts, and have just a 50 percent chance of survival over the following 30 days.

To put it succinctly, nothing about the disaster has been established concretely; not the cause, not the current conditions, not where the responsibility lies. Unlike the airplane crash investigation praised by Terada, there is no hope for new and reasoned plans to prevent a recurrence based on a firm understanding of the disaster's causes.

Even so, the fear of Terada's empty rice bin -- fear of lost employment, declining production and power outages during the summer heat -- has fueled the movement to restart Japan's idled nuclear reactors.

The government has slapped together a compromise, string-and-chewing-gum solution to nuclear safety issues, deploying auxiliary generators to plants and reinforcing the seawalls protecting them from the ocean. The very point the reconstruction design council was trying to make has been dropped from the discussion. That is the reality today.

Terada walked through the devastated areas following both the 1923 Great Kanto Earthquake and the 1933 Sanriku Earthquake and tsunami, and he did his best to sound the alarm on disaster prevention.

"Natural disasters return the moment you forget them," he is supposed to have said. In his volume of reflections on disasters, he laments that prompting people to act though they will not listen and will not open their eyes to danger "is harder-going than moving the stars in the sky."

We continue to see news on changes in the Earth's crust and volcanic activity. Most of the investigations into the nuclear disaster have been wrapped up, though because of high radiation levels it remains impossible to confirm the truth by direct observation of the reactors. We take this situation lightly at our peril. (By Takao Yamada, Expert Senior Writer)