Archive for the ‘Natural Disasters’ Category

« Older Entries
Newer Entries »

Sarkozy is using the Sendai quake and Fukushima troubles to play politics

March 16, 2011

Sometimes Sarkozy’s opportunism for gaining economic advantage is almost as vulgar as bunga bunga Berlusconi’s sex parties. But it is also – I think – a very clever move. Sarkozy is attempting to take a pre-emptive lead by being in the forefront of denigrating the Japanese nuclear program so that he can – by contrast – promote French nuclear technology and the French  nuclear plant manufacturer Areva and thus preserve the French dependence on nuclear power.

I predict his line will be that the Japanese nuclear plants were old fashioned and that French nuclear technology is different and inherently safe. He will walk the fine line between supporting “the Japanese people in their hour of need” while criticising TEPCO, its handling of the Fukushima problems and the outdated technology (the 6 reactors at Fukushima Dai-ichi were built starting in 1963 and came into operation between 1970 and 1979).

From the BBC:

No other country relies as heavily as France on nuclear power. It relies on nuclear power for 75% of it domestic supplies. It has 19 plants and 58 reactors. France is also at the forefront of nuclear technology, and President Sarkozy knows the debate over nuclear energy following events in Japan will affect the fortunes of the giant nucelar group Areva.

Like other countries, France is to check its nuclear reactors following the problems in Japan. But President Nicolas Sarkozy’s faith in the country’s nuclear programme seems unshaken. “France has made the choice of nuclear energy, which is an essential element of its energy independence and the fight against greenhouse gases,” he told his cabinet today. “This choice has been unseparable from an unfaltering undertaking to ensure a very high level of safety at our nuclear installations. I remain today convinced of the pertinence of these choices.”

French President Nicolas Sarkozy says he will call a special G20 meeting to discuss the energy sector in light of events in Japan. France currently holds the G20 presidency. France has also called a meeting of G7 finance ministers to respond to the crisis in Japan, Reuters reports. Finance Minister Christine Lagarde says the meeting will look at “how we can take part in their debt issues and how we can react on a financial level”.

From Paris, the BBC’s Christian Fraser says that France’s decision to offer it Tokyo-based citizens the chance to leave is partially motivated by domestic political problems. “Obviously it is a precaution and they might be accused of scaremongering but their new Foreign Minister Alain Juppe has been keen to get on the front foot, to show that they are in charge of the situation,” he said.

Related:  Does France have special information about Fukushima?

Tags:, , , , ,
Posted in France, Japan, Natural Disasters, Nuclear Power | Comments Off on Sarkozy is using the Sendai quake and Fukushima troubles to play politics

Fukushima Dai-ichi situation worsening and TEPCO is unsure how to proceed

March 16, 2011

1100 CET: The SDF helicopter cooling attempt was aborted for high radiation levels above the plent. New cooling attempts will use a water cannon on a fire truck borrowed from the US military.

From Paris, the BBC’s Christian Fraser says that France’s decision to offer its Tokyo-based citizens the chance to leave is partially motivated by domestic political problems.

0830 CET: Japanese TV reports that an SDF helicopter has taken off to spray water onto the plant. Helicopter spraying will be difficult to direct accurately and was thought to be a “last resort”. This suggests that other options are not feasible.

It is snowing in Fukushima.

0730 CET: Some workers have returned as radiation levels have fallen at the Fukushima Dai-ichi plant. While the Nikkei has risen some 6%, TEPCO shares have tanked. They were untraded but were bid down by the daily limit and are down 24.7%.

The operation could take on a military footing and responsibility could shift from TEPCO to the military. The Japanese Defence Minister has just said that if cooling efforts fail, the SDF would move in and SDF helicopters would spray water onto the plant.

TEPCO press releases are worthless and give virtually no information and the main source of public information is by the Chief Cabinet Secretary’s Edano’s press conferences. He himself is  impressive and generates some trust but it means that all information is being “politically” vetted so as not to be too alarmist. But just the filtering of information itself leads to assumptions (which may or may not be justified) that the actual information is worse than is being released. TEPCO’s communications and press conferences are not impressive.

Status at 0600 CET 16th March:

Work at the reactors may have stopped because radiation levels were too high. Radiation is fluctuating and has reached high levels at times. Levels were being reported in milli Sieverts(mS) rather than micro Sieverts (μS). For short periods levels upto 11 mS (11,000 μS). The normal working limit of 100 mS was raised 3 days ago to 250 mS and levels have been higher in parts of the plant.

The Fukushima Dai-ichi nuclear plant is being continuously subjected to new problems. All problems are unprecedented in the wake of the quake and the tsunami but TEPCO’s ability to cope is now raising cause for concern. Personnel from Toshiba, the manufacturer of the plant, have been called in by TEPCO. The initial plant design was to withstand earthquakes of magnitude 8.2 and it has been through a magnitude 9.0 quake some 15 times stronger than the design value. But the height of the tsunami wave was something not designed for. TEPCO spokesmen are getting testy when questioned and this is also an indication that they are frustrated and confused.

I have revised my view that TEPCO was in control of the situation. TEPCO seems to be unsure how to proceed.

Reactor #3 containment vessel is damaged and emitting steam (smoke?) and radiation. TEPCO does not know what it is. Workers near the central control room were evacuated temporarily(?). Workers are evacuated at levels higher than 259 Milli Sieverts.

Reactor #4 spent fuel pool is getting dangerous again. Pictures of the fire on 15th here were shown by TEPCO. It seems as if radiation levels here are also too high for workers to approach and attempt cooling. Winds and/or radiation levels are preventing the use of helicopters to dump water onto the reactor#4 spent fuel pool through a hole in the building roof. No other way to get cooling started seems to have been found.

Tags:, , , ,
Posted in Japan, Natural Disasters, Nuclear Power | Comments Off on Fukushima Dai-ichi situation worsening and TEPCO is unsure how to proceed

Reactor #4 at Fukushima Dai-ichi still unstable and could become critical.

March 15, 2011

While the situation at reactors # 1,  and 3 is stable with cooling by sea-water ongoing, the situation of the spent fuel pool at reactor no. 4 is still very serious and radiation leakage is still continuing. Reactor no. 2  suppression vessel is damaged and cooling is ongoing but the situation was not yet considered stable. Radiation levels are too high for technicians to get close to the reactor #4 pool to inject sea-water. The pool temperature was at 84°C and double the normal temperature of about 40 °C. The 20km zone evacuation around the plant was completed on Tuesday afternoon.

The option of trying to drop water by helicopter through a hole in the roof has been discarded since the pool is offset from the hole.

The use of specialised fire trucks with equipment which would allow water to be injected into the pool is being considered.

Getting fresh cooling water into the pool is now becoming very urgent and unless this is achieved the situation could become critical. As the temperature increases hydrogen could be produced and another hydrogen fire with an associated release of radiation becomes more probable.

Reuters reports that “Two workers are missing after Tuesday’s explosion at one of the reactors at a crippled Japanese nuclear plant, the country’s nuclear safety agency said.

The agency did not identify the missing workers, but said they were in the turbine area of the No.4 reactor at the Fukushima nuclear plant, which was damaged by last Friday’s earthquake and tsunami”.

Tags:, , , ,
Posted in Japan, Natural Disasters, Nuclear Power | Comments Off on Reactor #4 at Fukushima Dai-ichi still unstable and could become critical.

Does France have special information about Fukushima?

March 15, 2011

o600 CET : Wednesday 16th: France is now urging its nationals in Tokyo to leave Japan or head to the south of the country, Reuters reports. It says Paris has asked the Air France carrier to provide planes for the evacuation. The BBC’s Chris Hogg in Tokyo says the evacuation will begin on Thursday. Two French planes are already on their way to Japan.

It could be that France has access to some special information that the problems at the Fukushima Dai-ichi nuclear plants are much worse than anything being reported in Japan or by the IAEA, but the almost orchestrated negativity from French Agencies is noteworthy.

Politicians and agencies are positive about support for Japan regarding the earthquake and the tsunami, but the negativity  is focused around the Fukushima nuclear plant and is particularly noticeable from Agence France Presse, the French Nuclear Agency and French Radio.

I tend to be extremely suspicious of  French nuclear politics and cannot help feeling that there is an agenda here which involves being as negative as possible about the Japanese nuclear industry to later show up how the French nuclear industry is so much better.

  1. France’s nuclear safety authority says it classifies the Fukushima plant accident as level six. The maximum is level seven, used only once for the 1986 Chernobyl accident, Reuters reports. The Japanese Nuclear Agency has classified the event as Level 4.
  2. Europe’s Energy Commissioner says Japan’s nuclear disaster is an “apocalypse”, adding that Tokyo has almost lost control of events at the Fukushima power plant, AFP report.
  3. AFP reports that several countries are screening passengers on flights arriving from Japan.
  4. Radio France to withdraw staff in Japan after nuclear accidents: Dow Jones

But at the same time France’s Foreign Minister Alain Juppe has said: “We expressed our admiration for the dignity and the courage shown by the Japanese during this unprecedented ordeal. We expressed our confidence in the way the Japanese authorities have faced the aftermath of the disaster with such efficiency, which the whole world has recognised.”

Tags:, , , , ,
Posted in Alarmism, France, Japan, Media, Natural Disasters | 3 Comments »

Status at Fukishima Dai-ichi and Dai-ni nuclear power plants

March 15, 2011

1428 CET: Quake of magnitude 6.2 in Shizuoka south of Tokyo in the Tokai region of central Japan at approx. 10km depth reported on NHK World. Inland quake and therefore no chance of a tsunami. Nuclear plants in Shizuoka not affected and continue operation. No effects of this quake on TEPCO plants reported. Buildings in Tokyo reported to be swaying. JR Tokai Shinkansen trains suspended.

1400 CET: Radiation leak risk increases as TEPCO unable to pour water into No. 4 reactor’s storage pool for spent fuel.

1300 CET: Reuters – The International Atomic Energy Agency says Japan has monitored 150 people for radiation levels and carried out decontamination measures on 23

Radiation too high for TEPCO personnel to stay in Fukushima nuke plant control rooms

From Kyodo News: 1200 CET (2000 Local time)

The following is the known status as of Tuesday evening for each of the six reactors at the Fukushima No. 1 nuclear power plant and the four reactors at the Fukushima No. 2 plant, both in Fukushima Prefecture, crippled by Friday’s magnitude 9.0 earthquake and ensuing tsunami.

Fukushima No. 1

— Reactor No. 1 – Cooling failure, partial melting of core, vapor vented, hydrogen explosion, seawater pumped in.

— Reactor No. 2 – Cooling failure, seawater pumped in, fuel rods fully exposed temporarily, damage to containment system, potential meltdown feared.

— Reactor No. 3 – Cooling failure, partial melting of core feared, vapor vented, seawater pumped in, hydrogen explosion, high-level radiation measured nearby.

— Reactor No. 4 – Under maintenance when quake struck, fire caused possibly by hydrogen explosion at pool holding spent fuel rods, pool water levels feared receding.

— Reactor No. 5 – Under maintenance when quake struck.

— Reactor No. 6 – Under maintenance when quake struck.

Fukushima No. 2

— Reactor No. 1 – Cooling failure, then cold shutdown.

— Reactor No. 2 – Cooling failure, then cold shutdown.

— Reactor No. 3 – Cold shutdown.

— Reactor No. 4 – Cooling failure, then cold shutdown.

Tags:, ,
Posted in Japan, Natural Disasters | 2 Comments »

The Great Sendai Quake: Radiation surged from Fukushima Dai-ichi and now decreasing

March 15, 2011

1100 CET: UN’s weather agency says Japanese winds are dispersing radioactive material over the ocean, and there is no danger for Japan or the region for now.

Tohoku Electric will introduce electricity “rationing” with rotating blackouts starting from Wednesday.

TEPCO has come in for strong criticism from the PM’s office for being slow with information.

Kan strongly ordered the company not to withdraw its employees from the power plant, which has been facing a series of problems since Friday’s massive quake, ranging from explosions to radiation leaks.

”In the event of withdrawal from there, I’m 100 percent certain that the company will collapse,” Kan said. ”I want you all to be determined.”

The government, as well as the public, has been dissatisfied with the company’s way of releasing information regarding the crippled nuclear plant.

A man in his twenties and a 74 year old woman were rescued from under debris today – 4 days after the quake.

0930: Kyodo News – Water at spent fuel pools (which reactor? #4, #5 or #6?) may be boiling reducing the water in the pool. Cooling water is to be pumped in.

Is this also what happened at reactor#4? Reactors #4, 5 and 6 were not in operation when the quake and tsunami hit. There seem to be two categories of problems –

  1. at the operating reactors #1, 2 and 3 which all shut down automatically but where lack of cooling caused by a blackout of emergency power by the tsunami wave then led to uncovering of fuel rods and which in turn led to hydrogen explosions, and
  2. at the non-operating reactors #4, 5 and 6 where cooling to the spent fuel pools were compromised also due to loss of emergency power after the tsunami wave. At reactor #4, this somehow led to a fire during which a surge of  radiation leakage occurred. Temperatures are also rising in the spent fuel pools of reactors #5 and 6.

0830 CET: Nuclear designer states that the problem was a station blackout due to the high tsunami and loss of power to the cooling systems.

Press Conference by Chief Cabinet Secretary Edano.

Radiation at the plant perimeter was down to 595 μS at 3.30pm local time which is much higher than normal but not dangerous. For a period in the morning at around 0930 local time it was at the 11,000μS level which in one hour is equivalent to a lifetime dose. Radiation levels are worrying but they are decreasing and we are hopeful. The PM’s instructions to evacuate from the 20 km zone and to stay stay indoors for people in the 30 km zero was a matter of law. The fire at reactor #4 started at 0930 and is now out. This may have caused the radiation surge. Reactor #4 was not in operation but being refuelled(?). Reactor #2 is still being cooled and the rods are thought to be under water now so that the cooling seems to be functioning. Cooling for #1 and #3 continues stable. Temperatures have also risen at #5 and #6 gradually because after the tsunami the power to the cooling is not functioning properly and this is being watched closely and additional measures are being taken. Reactors #4, 5 and 6 were not in operation but some cooling is still necessary for the spent fuel pool. The radiation release after the fire at reactor #4 was probably from the spent fuel pool(?).

Small temperature rise has been observed at spent fuel pool at Fukushima reactors #5 and #6 which were not in operation and is being watched but no cooling has been needed to be applied so far.

0730 CET: The crisis around the Fukushima nuclear plant is diverting attention from the over 300,000 evacuees and the search and rescue efforts. Wintry weather is making things worse for all those displaced.

0700 CET Status:

Reactor No.2 at Fukushima Dai-ichi  has also suffered an explosion, the third reactor to do so. The containment vessel may be damaged. Some of the fuel rods are still exposed.

A fire at reactor no.4 broke out at 0938 local time and has now been put out. The roof of the building of reactor no.4 was damaged. A surge  of radiation leakage may have coincided with the fire.

Radiation levels dangerous to health were measured at the plant perimeter for short times.

Raised levels are measurable in the wind path which is towards Tokyo currently.

People within  the 20 – 30 km radius  are told to stay indoors. All within the 20 km zone are subject to an evacuation order.

A no-fly zone has been established in a 30 km radius zone around the plant.

NHK is broadcasting advice on precautionary measures for individuals when they are being advised to stay indoors.

Cooling efforts for reactors #1 to 3 are continuing.

IAEA believes the reactor containment vessels themselves are undamaged.

Tags:, ,
Posted in Japan, Natural Disasters | Comments Off on The Great Sendai Quake: Radiation surged from Fukushima Dai-ichi and now decreasing

The Great Sendai Quake: Fukushima Dai-ichi reactor no.2 still critical

March 14, 2011

2230 CET: 0617  local time — Chief Cabinet Secretary Edano says that reactor No.2 remains unstable. As of 0300 local time on Tuesday, pressure inside the reactor container had dropped and it was believed seawater had been pumped in succesfully, Tepco said, according to the Kyodo news agency. However, Tepco admitted that it had not yet been able to confirm that water levels inside the reactor had risen. The fuel rods were fully exposed at 2300 local time on Monday night.

2000 CET: Japanese media are concentrating on human stories and playing down the nuclear danger. Foreign media seem to be competing to see who can be most alarmist. The truth is probably somewhere in between.

It is now 4 am on Tuesday in Fukushima and Kyodo News reported at 0346 local time that sea water cooling of reactor no.2 has restarted. It has been about 4 hours since the announcement of exposed fuel rods and about 3 hours since the faulty valve was reported fixed. Since it is unclear how long it will take to get the fuel rods fully immersed again, this second exposure of the fuel rods could be significantly longer than the 2.5 hours of the first exposure. Once again with very hot fuel rods the cooling water will first evaporate and pressure could rise. With every venting of steam there will be some radiation leakage.

1700 CET:  It seems the faulty valve on reactor no.2 for steam venting and which prevented the pumping in of cooling water has been accessed and fixed.

TEPCO reported that when reactor no.2 at Fukushima Dai-ichi nuclear plant released steam earlier on Monday radiation levels were found to be twice the maximum levels previously detected, but the levels dropped sharply. The radiation levels at the front gate of the power plant were found to be 760 μS at 9:35 p.m.; 3,130 μS two minutes later; and 400 μS by 10:15 p.m.

1600 CET: FLASH from Kyodo NEWS. Fuel rods at reactor No.2 fully exposed again.

From NHK – A confused report in translation but it may be that ingress of sea water is being stopped by a valve which has closed and is preventing the evacuation of air. Is the pressure too high inside the reactor?? A fear is that the water has evaporated in which case it could be a steam pressure building up.

Putin and Medvedev have stated that Russia has a moral responsibility to assist Japan. Oil and Gas supplies and upto 6,000 MW of electricity are being spoken of. It is now midnight in Sendai and temperatures are down to about 2 °C and will be dropping to freezing in a couple of hours.

1500 CET: Reactors Nos. 1, 2 &3 at Fukushima Dai-ichi are all cooling. But fuel rods at reactor no. 2 were fully exposed for 2.5 hours. Coolant levels are now rising. Some radiation leakage did occur and the fully exposed fuel rods must have partially melted. Reactor buildings 1 & 3 suffered hydrogen explosions which removed the roofs and part of the building walls.

Russian monitoring stations in the east of the country (Vladivostok) have not so far measured any increases of radiation.

There are no adverse reports concerning Reactors 4, 5 & 6.

Kyodo News:

Fuel rods at the quake-hit Fukushima No. 1 nuclear power plant’s No. 2 reactor were fully exposed at one point after its cooling functions failed, the plant operator said Monday, indicating the critical situation of the reactor’s core beginning to melt due to overheating.

The rods were exposed as a fire pump to pour seawater into the reactor to cool it down ran out of fuel, Tokyo Electric Power Co. said. The firm had reported the loss of cooling functions as an emergency to the government.

TEPCO said water levels later recovered to cover 30 centimeters in the lower parts of the fuel rods.

Later in the evening water levels had risen to cover 2m of the fuel rods.

Tags:, ,
Posted in Japan, Natural Disasters | Comments Off on The Great Sendai Quake: Fukushima Dai-ichi reactor no.2 still critical

The Great Sendai Quake: Millions were saved by good engineering

March 14, 2011

The size of the quake and tsunami and death and suffering is enormous. It was an event that comes once in a millenium.

The danger and risk is not over.

Fukushima Dai-ichi nuclear plant is still in a critical situation.

But the Great Hanshin earthquake in 1995 and the destruction in Kobe where “earthquake proofing” was limited because there had not been a sizable quake in the region for some 400 years, and some 6,000 people died after a 7.4 magnitude quake, puts this 9.0 magnitude quake into perspective. The Sendai quake was 8,000 times stronger than the Kobe quake and the massive tsunami was a feature not present in Kobe. In some areas the tsunami came rushing in just minutes after the quake. It is thought that the failure of the 13 emergency diesel generators at Fukushima Dai-ichi were caused by the arrival of the tsunami wave rather than by the quake and that the failure of coolant pumping has led to all the subsequent problems.

It has been good engineering, well developed and strict building standards and a tsunami warning system which has prevented the death toll from being counted in hundreds of thousands or even millions. The events in Fukushima Dai-ichi following this massive quake and tsunami must also be put into perspective against the Three Mile Island and Tjernobyl incidents where there were no natural disasters to be coped with. The majority of the casualties and the damage seems to have been due to the tsunami rather than directly due to the earthquake itself.

Engineering and technology will keep advancing and will never be perfect but I am quite sure that good engineering has saved a very great many.

Tags:, , ,
Posted in Engineering, Japan, Natural Disasters | Comments Off on The Great Sendai Quake: Millions were saved by good engineering

The Great Sendai Quake: Status at Fukushima Dai-Ichi still critical

March 14, 2011

Note ! My main sources are NHK, Kyodo News, Nikkei News, Asahi News, the BBC and CNN live blogs, Swedish Radio and some private emails. To follow only one of them is insufficient because even at such a time all of them tend to put some political “spin” into their reporting. CNN in my opinion is the most alarmist of these.

1400 CET: The fuel rods at reactor No.2 were fully exposed  for about 2.5 hours. The coolant level has now been raised by about 2m.

1300 CET: Press Conference by Chief Cabinet Secretary Edano: The pump failure at reactor no.2 was due to diesel fuel running out and took time to restart. Pumping has been resumed and the reactor is currently cooling. If cooling can be kept going stability will be reached. But some melting of the furl rods has likely taken place. The radiation measured was at a tolerable level for humans.

Some radioactivity had been detected at the plant periphery and surrounding area. A coolant pump at reactor No.2 has failed. Some steam is to be vented. There is conflicting information on the one hand about cooling working, coolant levels increasing by 30 cm but on the other hand also about 80cm of fuel rods being exposed, the possibility of fuel rod melting and of steam and gas being vented. But the radiation leakage is probably due to fuel rods melting at reactor no. 2 as well.

1230 CET: The coolant level at reactor no.2 is recovering and has gone up by 30cm.

Total number of people displaced now exceeds 500,000.

1100 CET: The problems with Reactor No.2 seem to have been losss of power and loss of all pumping capacity after the explosion at reactor No. 3. Power is now restored (by mobile generators?). At Fukushima Dai-ichi it seems (I hope) like a case of “Still critical but catastrophe avoided”.

TEPCO has introducing rotating blackouts. About 25% of Japan’s electricity generating capacity is down. Temperatures in Sendai will drop to freezing overnight and will affect over 300,000 people who are displaced from their homes. Rain – with some snow – is also expected tomorrow. Some offices of foreign companies in Tokyo have decided to close for the week.

By the numbers: 1,834 deaths confirmed with 15,000+ unaccounted for. 24,000 are known to be stranded and awaiting rescue. At least 6,200 buildings destroyed with at least 63,000 damaged.

0945 CET: Confirmed that cooling efforts at reactors No.1 and reactor No.2 have been successful. Whether and when all nuclear reactions have been or will have been shut down is not clear.

0930 CET: Kyodo News says that reactors No. 1 and 2 have been “pulled out of emergency” but the meaning of this is not clear for me. Presumably the power loss at reactor 2 after the explosion at reactor 3 has now been restored and pumping of sea water has restarted. But since fuel rods were exposed at reactor 2, I am not sure if this means that the risk of a hydrogen explosion at reactor 2 has gone. Also presumably reactor 3 has not yet been pulled out of “emergency”.

Tokyo Electric has started some power outages. Though these were due to begin in the morning they started only at 5pm because many have responded to calls to reduce their electricity consumption.

0900 CET: Reactor No.2 has lost all its coolant. Pressure in the building is rising and a third hydrogen explosion is possible. Clearly the fuel rods in reactor No. 2 have also been exposed. PM has called the situation “alarming”. US helicopter has detected radiation and the US aircraft carrier has suspended aid activity says Kyodo News. Fire being fought at Tohoku Electric’s thermal power plant in Fukushima.

Wintry weather expected with snow and moisture in next 48 hours in the Sendai region increasing risk of mud landslides. Heating is a problem at evacuation centres. Updated

0730 CET: Reactor No. 3 building has also suffered what seems to be a hydrogen explosion and the walls of the building have collapsed as with reactor No.1 building.  The explosion has relieved the pressure in the building. The fuel here is uranium and plutonium and potential radiation leaks are much worse than from reactor No.1 building. Higher levels of radiation than from reactor No. 1 have been observed but the reactor vessel is  said to be undamaged and safe. In the building, radiation levels of 50 μS and and outside the building  20 μS /hour were reported.

The real worry is that the cooling water being frantically pumped in is leaking away and not filling up the reactor vessel as it should. Reactor No.2 is also having sea water being pumped in but there is no report of fuel rod exposure here. Coolant levels are falling.

Reactor No. 4 is also giving cause for concern.

Tags:, , , ,
Posted in Japan, Natural Disasters | Comments Off on The Great Sendai Quake: Status at Fukushima Dai-Ichi still critical

The Great Sendai Quake was due: Miyagi earthquake frequency is approximately every 30 – 40 years with large tsunamis every 800 – 1100 years

March 13, 2011
Earthquake and Tsunami near Sendai, Japan

Earthquake and Tsunami near Sendai March 2011: image NASA

The north east of Japan is subject to major earthquakes every 30 – 40 years. The last major quake was 32 years ago in 1978. But we have to go back 1142 years to the 869 Jōgan earthquake to find a similar magnitude and accompanying tsunami. This has led Japanese analysts to call the Great Sendai Quake of 2011 a one in a thousand year event.

“Three tsunami deposits have been identified within the Holocene sequence of the Sendai plain, all formed within the last 3,000 years, suggesting an 800 to 1,100 year recurrence interval for large tsunamigenic earthquakes. In 2001 it was reckoned that there was a high likelihood of a large tsunami hitting the Sendai plain as more than 1,100 years had then elapsed”.

The 1978 Miyagi earthquake occurred at 17:14 local time on 12 June. It had a magnitude of 7.7 and triggered a small tsunami. The earthquake caused 28 deaths and 1,325 injuries.

Earthquakes with similar magnitudes have occurred in this region periodically, about every 40 years. Such earthquakes include the ones that occurred in 1793, 1835, 1861, 1897, 1936, and 1978. The 2005 Miyagi earthquake is not considered to be the one that was expected to follow the 1978 Miyagi earthquake. More recent comparisons have confirmed the differences between the 1978 and 2005 events.

In 1978

Over a thousand passengers were stranded in Sendai railway station after bullet train services were stopped. Ten families were evacuated from their homes for fear of landslides. About 35,000 homes lost power supplies but electricity was restored for most within a few hours.

A highway in northeastern Japan was temporarily closed. Phone networks were snarled. Regional utility Tohoku Electric Power Co Inc said an 825,000-kilowatt (kW) nuclear reactor, the Onagawa No.3 unit near Sendai automatically shut down due to the quake. Japan’s largest oil refiner, Nippon Oil Corp, said it had started shutting down its 145,000 barrels per day Sendai refinery, although its facilities appeared to be undamaged.

In Tokyo, buildings shook violently and lamps swayed, sending workers scurrying to doorways.

But the last time an earthquake with a magnitude similar to that 3 days ago on 11th March was on 13th July 869 AD where traces of a tsunami have been found about 4km inland.

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.

The tsunami caused extensive flooding of the Sendai plain, destroying the town of  Tagajō. Archaeological investigations have identified the remains of 8th and 9th century buildings beneath the town, covered by sediments dated to the middle of the 10th century.

The estimated magnitude of the earthquake as 8.6 on the surface wave magnitude scale, has been taken from modelling of the tsunami. A source area of 200 km long by 85 km wide with a displacement of 2 m is consistent with the observed distribution and degree of flooding.

Three tsunami deposits have been identified within the Holocene sequence of the Sendai plain, all formed within the last 3,000 years, suggesting an 800 to 1,100 year recurrence interval for large tsunamigenic earthquakes. In 2001 it was reckoned that there was a high likelihood of a large tsunami hitting the Sendai plain as more than 1,100 years had then elapsed.

This time 1142 years after the 869 Jōgan earthquake and tsunami the focal zone was some 500 km long and 200 km wide with three simultaneous quakes within the zone.

Tags:, , , , , ,
Posted in Japan, Natural Disasters | 1 Comment »

« Older Entries
Newer Entries »