More Thoughts on Mt. Fuji’s Risks


Dr. Jorge Zanelli is a theoretical physicist at the Centro de Estudios Científicos de Santiago.

Read in Japanese (日本語 ) and Spanish.


Dear Mr. Matsumura,

I read with interest your article on the risk of Mt. Fuji’s possible eruption in the not so far future. Such a scenario is not only possible, but according to the experts it is highly probable. Consequently, all measures should be taken to avert any unnecessary risks to the population in the nearby region. This includes protection of all nearby communities, industrial facilities, hospitals, transport and communication infrastructure, etc. Each of these aspects has its own features and requires a different type of protection and safeguards. All of them should be carefully studied and protected, but also the combination of their risks must also be taken into account.

The number of towns and villages around Mt. Fuji appalls me. I don’t know anything about land use planning in Japan, but given the historical information available it seems obvious that the necessary precautions should have been taken before authorizing the construction of residences, industrial facilities, including nuclear power plants. I imagine that the emergency plans must be drawn in the event of an eruption, and this should include evacuation of civilians, protection of infrastructure and critical potentially dangerous facilities of all kinds. Your article draws the attention to the risk of a nuclear accident triggered by an eruption, which is a legitimate concern. It seems to me that a greater hazard would be the lack of a rational plan to handle the emergency, be it nuclear or of any other sort.

In the particular case of the Hamaoka nuclear power plant, the past record of its operation is so dubious that it doesn’t require the threat of a volcanic eruption to recommend its shutdown. I have not studied the case in depth, but continued unchecked operation of this plant seems to me a greater risk to the surrounding area than the radiation released in the event of an accident similar to that at Fukushima.

Going back to the more general issue of the risk of a nuclear accident triggered by a volcanic eruption or other natural disasters, I don’t believe decommissioning all nuclear reactors to be the only option. The situation is not so different from that of other vulnerable and potentially harmful industrial infrastructures (pharmaceutical, pesticides, oil refineries, explosives, fertilizers, industries producing or employing heavy metals, etc). I am sure the engineering know-how exists to handle industrial emergencies of this sort around Mt. Fuji or anywhere else in Japan.

In order to make a rational decision about the general problem one should address the following questions:

  1. How dangerous a given industrial facility really is. This requires an assessment of the absolute risk under normal operations as well as in the event of an accident.
  2. How does nuclear compare with other industries?
  3. Is it possible to keep the risks at an acceptable level, or is removal the only option?
  4. What is the cost and what are the benefits of nuclear shut down?

My understanding, from reading many sources and talking several to experts, is that the threat of low dose radiation has been exaggerated by the linear no-threshold hypothesis (LNTH), for which there seems to be no sound scientific basis. Without going into the technicalities, the LNTH asserts that if a certain radiation dose produces cancer in 50% of a population, half of the same dose produces the same effect in 25% of a similar population. This apparently “obvious truth” makes it plausible that infinitesimal doses are likely to produce enormous number of victims in sufficiently large populations.  Following this line of argument for example, some serious experts [“Poisoned Power”, by John W. Gofman, Ph.D., M.D. and Arthur R. Tamplin, Ph.D.] predicted in 1979  333 fatal cancers or leukemias” as a result of the TMI accident, which did not materialize.

Even if the nuclear industry had learned nothing from Fukushima (which I doubt) and an eruption combined with an earthquake and/or tsunami produces a crippled reactor without external electric support, the environmental impact and radiation effects on the residents in the area would still be modest compared to the huge direct impact of the natural disaster or other indirect effects like the lack of food, shelter or medical attention.


I am convinced that a rational approach can lead us to better decisions in a more stable and sustainable path. This usually means deviating from the “obvious truth”, which is just a name for intuitive understanding.

Best regards, J. Zanelli


Dr. Jorge Zanelli is a theoretical physicist at the Centro de Estudios Científicos de Santiago and former chair of a presidential commission to assess the nuclear option for Chile.

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