March 23, 2011
Tsunami Risk To Nuclear Plants Foreseen And Ignored

Of course a scientist warned of the tsunami risk to nuclear plants and was ignored.

Yukinobu Okamura, a prominent seismologist, warned of a debilitating tsunami in June 2009 at one of a series of meetings held by the Nuclear and Industrial Safety Agency to evaluate the readiness of Daiichi, as well as Japan’s 16 other nuclear power plants, to withstand a massive natural disaster. But in the discussion about Daiichi, Okamura was rebuffed by an executive from the Tokyo Electric Power Co., which operates the plant, because the utility and the government believed that earthquakes posed a greater threat.

Read the full article. One defense of Tepco and Japanese regulators was that the recent tsunami was not foreseeable. But that's not the case.

Back in 869 AD a similar tsunami occurred.

“The 869 Jōgan earthquake and tsunami struck the area around Sendai in the northern part of Honshu on the 13 July. The earthquake had an estimated magnitude of 8.6 on the surface wave magnitude scale. The tsunami caused widespread flooding of the Sendai plain, with sand deposits being found up to 4 km from the coast.”

While the nukes have gotten enormous attention the deaths were caused directly by the tsunami. All those thousands of who died might have been saved if the Japanese had paid more attention to their geological researchers. So what risks are we under today that do not get the attention they warrant?

The 869 earthquake and tsunami were part of a longer run pattern.

Their results, published in the Journal of Natural Disaster Science, indicated that the medieval tsunami was probably triggered by a Magnitude 8.3 offshore quake and that waters spread more than 4km from the shore.

They also found evidence of two earlier tsunamis on the scale of the Jogan disaster, leading them to conclude that there had been three massive events in the last 3,000 years.

Or maybe the cycle is every 500 years?

"[Tsunamis] have accompanied earthquakes off the Sanriku Coast over a 500-year cycle. There was concern [such a massive quake] would occur in the near future," said Active Fault and Earthquake Research Center chief Yukinobu Okamura.

Smaller tsunamis have hit more often 0 - and will continue to do so.

Large offshore earthquakes have occurred in the same subduction zone in 1611, 1896 and 1933 that each produced devastating tsunami waves on the Sanriku coast of Pacific NE Japan.

That coastline is particularly vulnerable to tsunami waves because it has many deep coastal embayments that amplify tsunami waves and cause great wave inundations.

A 2007 paper by a group of Japanese researchers predicted tsunami recurrences at about 1000 year intervals. So they were predicting what happened.

In Sendai plain, the tsunami deposits extend about 1 to 3 km from the coast line at that time, which is estimated as about 1 km inland of the present coast. In Ishinomaki plain, the tsunami deposits extend > 3 km from the estimated coast line, which is about 1-1.5 km inland of the present coast. Multiple sand layers indicate recurrence of such unusual tsunamis with approximately 1,000 yr interval. We computed tsunami inundation in both plains from several types of tsunami source models such as outer-rise normal fault, tsunami earthquakes (narrow fault near trench axis), interplate earthquakes with fault widths of 50 and 100 km. Comparison of the computed inundation area with the distribution of tsunami deposits indicates that only an interplate earthquake source with 100 km width (depth range of 20 to 50 km) can reproduce the observed distribution of tsunami deposits in both Sendai and Ishinomaki plains. This source (Mw=8.1 to 8.3) is much larger than the anticipated Miyagi-oki earthquake (M~~7.5) with 99% probability in the next 30 years.

What other predictable disasters await us?

Share |      Randall Parker, 2011 March 23 11:00 PM  Dangers Natural Geological

Salman Khan said at March 24, 2011 10:50 AM:

Japan has a bad history of natural disasters. If it was foreseen also then ignorance should not be there.

ck said at March 24, 2011 5:02 PM:

Yeah, like there's ever been any advance in the history of the human race that wasn't poopood by grant seekers(scientists),shaman,chiropractors,herbalists and other shakedown artists.

PeterVW said at March 25, 2011 7:01 AM:

Actually, there is a scientist who warns about ANY potential risk. He then writes a report. When some unwanted eventuality occurs, from whichever risk, the person who identified that particular risk gets his/her report out and displays it for all to see.

John Cooper said at March 25, 2011 3:31 PM:

The references, if authorities [or even better -- engineers] 'pay attention' to them, do not have that much predictive value -- even today with fresh events as examples.
Specifically, the magnitude range of 8.1 to 8.6 is a lot lower than the actual 9.0+ March earthquake in terms of energy. And the concept to 500 or 1000 year cycles is a bit broad when designing structures or systems with much shorter lifespans.
For balance, please look at the actual design parameters for the Fukushima Nuclear site; it is not as if General Electric ignored the possibility of earthquakes and tsunami.

We have similar warnings about the next 'New Madrid' seismic event in the United States -- are we evacuating the area? Are we designing buildings to resist huge earthquakes in the region? Are we prepared for the rivers to run backwards?
Afterward, I am sure someone will point out the warnings and how 'we should have paid attention.'

Here is one for you -- some large satellites will fall to earth over the next fifty years. One could end up anywhere. Should you have a plan to retrofit your house to withstand impact?

Bee said at March 26, 2011 6:40 AM:

Please think more clearly Randall ... It is very unlikely that they were ignored ... They were deemed too expensive for the risk ... There are a huge number of low probability risks ... Acting on all would be impossible ...

Randall Parker said at March 26, 2011 9:44 AM:


But I am thinking clearly. The very concept of "low probability" is nonsense when it is not possible to calculate probabilities accurately. If I have a factory that makes millions of some widget then I can calculate probability that any one widget will be defective. But calculate probability of a 10 meter tsunami? How? Seriously, how?

The bias I see is "Can't calculate probability and so lets treat it as a very low probability". Desires for job security, advancement, and profits create this bias. The bias has no rational justification.

Seriously, do you really think the TEPCO executive who "rebuffed" Yukinobu Okamura thought hard enough about the risk to assign a probability to it? Think he assigned engineers to work up a risk model?

John Cooper,

If nuclear power plants won't be designed to handle cycles that are 500 to 1000 years long then nuclear power plants should not be built.

Guys, I've long been pro-nuclear. But arguments like these are starting to make me think the nuclear power industry can't be trusted with such an awesome responsibility.

Randall Parker said at March 26, 2011 6:10 PM:

An NY Times piece draws attention to inadequate inspections and regulators who were captured by their industry:

The decision to extend the reactor’s life, and the inspection failures at all six reactors, highlight what critics describe as unhealthy ties between power plant operators and the Japanese regulators that oversee them. Expert panels like the one that recommended the extension are drawn mostly from academia to backstop bureaucratic decision-making and rarely challenge the agencies that hire them.

Lots of regulatory agencies get captured by their target industries. The US SEC is a great example. Ditto the FDA which helps long established drug makers with barriers to new entrants. But the stakes are so much higher with nuclear power.

Bruce said at March 27, 2011 8:31 AM:

And the the green "industry" owns the IPCC.

I think many people can than the greens for delaying new nuclear power plants. Old ones don't get replaced because it is way too hard.

ck said at March 27, 2011 4:13 PM:

I just wish that all luddites could be forced to live in a pre-industral world for six months.

Lono said at March 28, 2011 7:44 AM:

"Guys, I've long been pro-nuclear. But arguments like these are starting to make me think the nuclear power industry can't be trusted with such an awesome responsibility."

And now, Randall, you are seeing what I have been saying - we cannot expect to survive the singularity using the same mindset and tribal hierarchies we have depended on before it.

"We cannot solve our problems with the same thinking we used when we created them."

- Albert Einstein

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