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Explanation 2

The Tokai earthquake is approaching

The Tokai earthquake is an earthquake which is most often predicted its generating time. The energy has accumulated for about 150 years after the last Tokai earthquake happened. (Fig. 7)

If the Tokai earthquake happens now, it will become the earthquake of a 15 times as many scale as the Hyogo southern part earthquake. The scale of an earthquake becomes larger as generating is overdue.

Fig. 7

  Around Shizuoka prefecture, Kii Peninsula and Shikoku, the Philippine Sea Plate is sunk and crowded with the speed of 4cm down to the Japanese Islands every year. Therefore, the plate boundary type great earthquake has happened every 100 to 150 years.

The great earthquake whose source region is around Shizuoka prefecture to Omaezaki is called Tokai earthquake.
The great earthquake whose source region is around the golf of Ise to Mie prefecture is called the southeast sea earthquake.

Tokai and the southeast sea earthquake united and happened in 1854. This is called Ansei Tokai earthquake.
The southeast sea earthquake happened independently in 1944. This is called Showa southeast sea earthquake. However, the "Showa Tokai earthquake" did not happen.

147 years have passed since the last Ansei Tokai earthquake as of 2001. It was 147 years to the Ansei Tokai earthquake from the Houei Tokai earthquake. The energy that causes an earthquake has accumulated.

However, there are an idea "the Tokai earthquake happens independently", and an idea of saying, "It does not happen unless the southeast sea earthquake does" If the Tokai earthquake happens independently, "now" will be the generating time. The energy will be 15 times of the Hyogo southern part earthquake's one.

If it happens with the southeast sea earthquake, it will generate about the middle of the 21st century or later. The energy in that case increases several times comparing with the time of happening independently.

According to the estimate of governmental Headquarter of Earthquake Research Promotion announced on September 27 in 2001, the probability that the southeast sea earthquake will occur within 30 years after present is 40 to 50%.

Ashihama and Miyama-cho of Mie Prefecture are also contained in the source region according to the long-term earthquake evaluation of the Headquarter of Earthquake Research Promotion Nankai Trough.

The source region of an assumption Nankai earthquake and Hamaoka earthquake


The position of the Hamaoka nuclear power plants

 The Hamaoka nuclear power plants are in right above the assumed source region of the Tokai earthquake. (Fig. 8)

Fig. 8

 The focus of the earthquake is a tomographic layer with area. The 60km x 115km whole base rock is destroyed, and it shifts and moves at the Tokai earthquake. The shock becomes a big earthquake.

Fig. 9
Fig. 10

 Fig. 9 is seismic intensity prediction of the Tokai earthquake by Shizuoka Prefecture. The position of the Hamaoka nuclear power plants is added.
The small figure 10 is the seismic intensity in Kobe at the Hyogo southern part earthquake. Both show seismic intensity 7 (30% or more of a building collapses) in red. Both of the maps are the same scales. You would recognize the size of the scale of the Tokai earthquake.

Fig. 8 and Fig. 9 are based on the focus model of Mr. Katsuhiko Ishibashi in 1976. Shizuoka Prefecture has performed damage assumption by the Ishibashi model for a long time.

Taking in the experience of the subsequent Hanshin Awaji great earthquake, the damage assumption was revised upward and announced in May 2001.

The third earthquake damage assumption of Shizuoka

On the other hand, from the accumulation of the data for 20 years, which aimed at the forecast just before the Tokai earthquake, the form of a plate boundary is becoming clearer than before.

Then, the board of inquiry by 16 researchers was established in the Central Disaster Prevention Council of the government in 2001, and their result was released before December.

Expanding the focus tomographic layer with its 30%, the range containing a little less than six seismic intensity spread around Chigasaki, Suwa and Nagoya. (Fig. 10-2)

Fig 10-2

Fig 11

The Philippine Sea Plate has sunk in the basement in Hamaoka at about 4cm speed per year from the southeast side to the northwest side. Therefore, the base rock of Hamaoka is drawn in little by little. (Fig. 11)

As shown in a figure, comparing with Kakegawa of 20km inland, Hamaoka inclined every 5mm and has fallen every year. Into a base rock, distortion accumulates with it every year. And when a limit is reached, a base rock is destroyed in an instant, and the land shifts and moves.

At this time, most of the old sediments will upheaval only in several 10 seconds. It is expected that the amount of upheaval becomes some 1m.

Can the nuclear power plants of Hamaoka resist the Tokai earthquake?

  It came to be thought only 30 years ago that the Pacific plate has sunk down to the Japanese Islands. The thing of the earth is hardly understood yet. The problem is the location of the source region of the big earthquake and whether we will able to have the courage to accept our mistakes and stop the operation of those plants of Hamaoka.


The Tokai earthquake theory (Ishibashi model) was advocated.


No. 1 furnace (540,000 kw) of nuclear power plants of Hamaoka started to operate.


The Large-Scale Earthquake Countermeasures Act was enacted.


The No. 2 furnace of the nuclear power plants of Hamaoka (840,000 kw) started to operate


6 prefecture 170 cities, towns and villages of the Tokai area was specified as an earthquake disaster-measures special strengthening area


In the United States the Three Mile Island nuclear power plant meltdown accident happened.


The conflagration evil accident of the CHIERUNOVIRI nuclear power plant happened in the Soviet Union.


The No. 3 furnace (1,100,000 kw) of the nuclear power plants of Hamaoka started to operate.


The water leaked from a nuclear reactor pressure vessel piping welding part at the No. 1 furnace of the nuclear power plants of Hamaoka.


The No. 4 furnace (1,140,000 kw) of the nuclear power plants of Hamaoka started to operate.


The Hanshin earthquake occured.











They say that the important buildings of nuclear power plants were made with 3 times intensity of building standard law, but….   

The usual earthquake-proof standard is aimed at damage not attaining to a human life, even if a building breaks. However, in a nuclear power plant, radioactivity must not be allowed to leak.

They say that the nuclear power plants do not build on an active fault and the surrounding active fault is investigated, but…

When a dislocation arises in the underground base rock or the tomographic layer produced in the past moves again, its shock becomes an earthquake.

The size of the dislocation, which worked in case of the Hyogo southern part earthquake in 1995, is 15kmx45km. However, in Kobe, the gap has not arrived to the surface of the earth. The dislocation that caused this earthquake is not visible in Kobe. (Fig. 12)

Fig. 12

The active fault that is visible to surface of the earth is only a part of dislocation group, which may cause an earthquake. In a place where the active fault is appearing near, there is a lot of possibility that the more dislocation invisible is underground. The active fault appears at the place of 3 to 7km from the nuclear power plants of Hamaoka. (Fig. 13)

Fig. 13

the nuclear power plants of Hamaoka is in the crease where Omaezaki upheaves. There may be invisible active fault under the ground near the nuclear power plants.

Although the Tottori western earthquake happened in 2001 was a shallow earthquake of magnitude 7.3, it occurred in the place where the active fault was not known.

They say that it was designed to bear the biggest earthquake, but…

The earthquake-proof design of No. 1 and No. 2 furnace assumes the shake of an earthquake (acceleration) a maximum of 450gal. In case of No. 3 and No. 4 furnace, 600gal for the maximum important apparatus and 450gal for the reactor core-cooling device for emergencies, etc. As the reason, it supposes that the shake of the Ansei Tokai earthquake in 1854 was 450gal, and the earthquake of magnitude 8.5 is a marginal earthquake and the greatest shake by it may be 600gal. (Fig. 14, Fig. 15)

Fig. 14
Fig. 15

However, in Kobe, the shake of 800gal or more is recorded. The 818gal in the directions of north and south, the 617gal in the directions of east and west, and the 332gal in the vertical directions are recorded at the Kobe Marine Observatories at the Hyogo southern part earthquake in 1995. (Fig. 16)

600gal or more is recorded in several places. In SHIRUMA, about 900gal is recorded in 1994 in case of North Ridge Earthquake. (Fig. 17)

Fig. 16Fig. 18

The design of a nuclear power plant does not assume the shake of the Kobe average even for the maximum important apparatus of No. 3 and 4 furnace. For the reactor core-cooling device for emergencies only half of the shake of Kobe is assumed. In the No. 1 and 2 furnaces, which is built before a Tokai earthquake theory and have superannuated, even for the maximum important apparatus only half of the shake (acceleration) of Kobe is assumed.

Moreover, it is fault that the earthquakes by the active fault which worked within the past 10,000 years (at the surface-of-the-earth portion) are "the earthquake which may happen in the future", and the earthquakes by the active fault which worked within the past 50,000 years (at the surface-of-the-earth portion) are "the earthquake which is not realistic about".

A part of dislocation that caused the Mikawa earthquake in 1945 worked for the first time in 100,000 years (at the surface-of-the-earth portion).

They say that it is constructed directly on a hard base rock, but…

Hearing the word "a hard base rock", an ordinary person will visualize "a hard stone." However, the foundations of a nuclear power plant are the stratum made from sand and muddy of 4 million years ago calling the layer of Sagara and Kakegawahiki. In engineering, it is classified into "soft rock."

Fig 18

The stratum imagined with "a hard stone" is not exposed unless in Minami-Alps. The focus model used for calculation of a shake of a nuclear power plant is a simplified one to understand the natural figure roughly. However, at the Tokai earthquake it is thought that many sheets of the focus dislocations move a time lag.

In Hamaoka, which exists right above a focus tomographic layer, the seismic waves simultaneously come from various directions. They may be amplified intricately.

Prediction of the shake from a focus model is average value. We should perform at maximum assumption of the nuclear power plant, which must not break by any means.

Professor of Kobe University, Katsuhiko Ishibashi who is the proposal person of a Tokai earthquake theory says, " the time history and self-sustaining time of an earthquake motion in Hamaoka must be more complicated, take more time and be far more intense than the point of the seismic intensity 7 of the Hyogo southern part earthquake." (The "science" 1997.10-month issue)

A seismic wave is amplified in the place where it goes into the soft rock from a hard base rock. A seismic wave is amplified again in the place where it goes into soft alluvium from soft rock. A seismic wave causes amplification, reflection, refraction, and interference depending on the underground structure.

Most structures of the deep place of underground are not known. In Kobe, it is thought that the seismic wave was greatly amplified in some places with the form of the hard base rock that continues from Rokkou to the bottom of Osaka Bay. Moreover, although the strong shake continued about for 10 seconds in Kobe, it is thought in Hamaoka at the Tokai earthquake it will continue about 2 minutes.

They say that earthquake-proof analysis is carried out by computer after making the model about important apparatus and experimenting on a large-sized oscillating stand, but…

Fig 19

It is said that the model experiment with the vibration of 1.5 times of the standard earthquake motion was done in No. 3 and 4 furnaces. 1.5 times is the safety margin that exceeded the error of construction, and superannuation. It is fault that it can bear to a 1.5 times strength by this reason.

Moreover, though each apparatus is equal to vibration, a way of shaking is different for every apparatus. Intense power can be produced in a connection part. If the welding part of a nuclear reactor and piping fractures, a fearful cooling-water loss accident will be caused. Does a complicated huge system shake as predicted?

Moreover, No. 1 and No. 2 furnaces are designed for 450gal, and superannuation is also progressing. As they had constructed more than 20 year ago, with a lot of neutron the nuclear reactor main part has got weak. The part where piping is welded to the nuclear reactor main part started stress corrosion cracking at the Hamaoka No. 1 furnace in 1988.

They are the parts that were said not to need to exchange at all to decommissioning. There cannot be any perfect construction, either. The leak from the bottom of a nuclear reactor was again found at the No. 1 furnace in November 2001.

Each building and apparatus have peculiar wavelength, when they vibrate. It is said that a firm nuclear reactor building vibrates finely (periodic 0.2? 0.5 seconds). Probably the piping will vibrate slowly although it changes with length or thickness. The low-pressure irrigation tanks of the reactor core-cooling device for emergencies etc. will vibrate very slowly.

If the peculiar wavelengths of apparatus and of an earthquake motion suit, it will be amplified and big power will be added. In Kobe the things leaped up. The thing will have been thrown if the power is added in the vertical direction more than gravity. It is not wrong that the power exceeding gravity acceleration (980gal) was applied.

Fig 20

The figure shows the computer simulation. You can see there that in Kobe the power exceeding gravity pressed the structure of a short oscillating cycle (0.15 to 1.2 second), and the very big power exceeding the twice of gravity has brought at the maximum.

The shake out of assumption is discovered at every damage earthquake.

Fig 21

  The highway fell down at the North Ridge Earthquake, which happened in Los Angeles suburbs early in the morning of January 17, 1994. Immediately after that, the Japanese government declared that as Japanese highways standard was different; there was no problem here.

Early in the morning of January 17, 1995, exactly one year after that, in Kobe the elevated roads of the Shinkansen and highways fell down, too. It was exactly "the shake out of assumption" In fact; the shake 800gal or more is recorded also like Kobe's one at the North Ridge Earthquake. (Fig. 17)

Also in the Nagano western earthquake in 1984, the marks of a jump stone phenomenon were found and it was presumed that the power exceeding gravity acceleration was applied. Probably, there was the same shake also in the past earthquake. Only men could not measure it. In the Niigata earthquake in 1964, liquefaction took place and the apartment fell.

At the Tokachi earthquake in 1968, the pillar of ferro-concrete broke and the first floor of a university building was crushed by perpendicular power. At the central Sea of Japan earthquake in 1983, it turned out that there was a way of shaking of long cycle vibration. At the North Ridge Earthquake in 1975, and the Hyogo southern part earthquake in 1976, the almost same earthquake motion as gravity acceleration was observed.

What shake out of assumption will be discovered at the Tokai earthquake?


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