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How many warnings and reminders does everyone need?
Japan 6.8 quake 22 Nov 2014
Epicenter location from USGS; Reactor coordinates from wikipedia

Yesterday, Japan was reminded, and reminded others, of the dangers of nuclear reactors in earthquake prone areas. The epicenter of the 6.8 quake was 24 km (15 miles) West of Nagano, Japan (reported as 6.2 by the USGS). Luckily the earthquake was at a distance of roughly 85 km (52 mi) from the 7 nuclear reactors at Kashiwazaki-Kariwa Nuclear Power Station and roughly 95 km (60 mi) from the 2 nuclear reactors at Shika Nuclear Power Station. From reports and models, the earthquake was probably felt as a 4.0 (or possibly a bit higher) at the two nuclear reactor sites.[1] Closer to the epicenter, homes were destroyed in Otari, as well as Hakuba.[2]

Of concern should be the Kurobe Dam, which appears about 24 km (15 mi) from the epicenter. It certainly should be checked. Unlike in the US, where there are multiple dams upriver from nuclear reactors, which risk failure from old age and/or earthquakes (both the dams and the nuclear reactors!), the Kurobe Dam does not seem to be upriver from any nuclear reactors, though some other dams may be. Reactors down-river from dams are supposed to have tsunami walls, but apparently do not in the USA. Would they be effective?

Nonetheless, both the Shika and Kashiwazaki-Kariwa Nuclear Power Stations may have active faults both under them and nearby, putting in mind California’s Diablo Canyon, except that the Kashiwazaki-Kariwa Nuclear Power Station with 7 reactors is the largest nuclear power station in the world by net electrical power rating, making it Diablo on steroids. Both Diablo Canyon and Kashiwazaki-Kariwa are at Tsunami Risk (See more below map).

The fault lines and the fault lines that were originally overlooked by Tepco surrounding the Kashiwazaki-Kariwa Nuclear Power Plant, CC-BY-SA-3.0, derivative work by Theanphibian from Tosaka
The fault lines and the fault lines that were originally overlooked by Tepco surrounding the Kashiwazaki-Kariwa Nuclear Power Plant“, CC-BY-SA-3.0, derivative work by Theanphibian from Tosaka http://commons.wikimedia.org/wiki/File:Kashiwazaki_Kariwa_Fault_Lines.PNG

Regarding the Seismicity of the Shika Reactors

On 16 July 2012 research done by the Japanese government did reveal the strong possibility that the S-1-fault beneath the power station might be active.http://en.wikipedia.org/wiki/Shika_Nuclear_Power_Plant
In March 2005 the government’s Headquarters for Earthquake Research Promotion announced that a 7.6 magnitude earthquake could occur if the whole Ochigata Fault Zone were to move at once. Hokuriku Electric did not take this possibility into account. The Ochigata fault is near the Shika reactor. It had previously been thought of as several smaller faults, but the Headquarters for Earthquake Research Promotion recognized the possibility that all these faults could move together as a single fault zone“. http://www.cnic.jp/english/newsletter/nit112/nit112articles/nit112shika2.html
Date:2006 March 27, 09:17 (Monday) Canonical ID:06TOKYO1592_a
… 1. (SBU) On March 24, the Kanazawa District Court ordered
the Hokuriku Electric Power Company (Rikuden) to shut down
operations at Unit Two of its Shika Nuclear Power Plant due
to safety concerns over its ability to withstand powerful
earthquakes… The plaintiffs pointed to a study commissioned by the GOJ’s Earthquake Research Committee that concluded there was a two percent chance that an earthquake with a magnitude of 7.6 or higher could occur along the 44-kilometer long Ochigata fault, which runs near the NPP. The unit was built to withstand a magnitude 6.5 earthquake.
https://www.wikileaks.org/plusd/cables/06TOKYO1592_a.html (Emphasis added)

Regarding the Kashiwazaki-Kariwa Nuclear Reactors’ Seismicity

Kashiwazaki-Kariwa is “the largest nuclear generating station in the world by net electrical power rating.

It was approximately 19 km (12 mi) from the epicenter of the second strongest earthquake to ever occur at a nuclear plant, the Mw 6.6 July 2007 Chūetsu offshore earthquake. This shook the plant beyond design basis and initiated an extended shutdown for inspection, which indicated that greater earthquake-proofing was needed before operation could be resumed. The plant was completely shut down for 21 months following the earthquake. Unit 7 was restarted after seismic upgrades on May 9, 2009, followed later by units 1, 5, and 6. (Units 2, 3, 4 were not restarted).

After the April 2011 earthquake, all restarted units were shut down and safety improvements are being carried out. As of November 2014 no units are restarted and no units are expected to restart until the end of 2015.[2]
On 26 April 2012 TEPCO said that it would recalculate the risks of earthquakes and tsunamis. This was done after reports published by four prefectures around the nuclear Plant, re-estimated the risks of potential earthquakes in the region:
Tottori Prefecture: a 220 kilometer long fault might trigger an 8.15 magnitude earthquake
Shimane Prefecture : 8.01 magnitude
Ishikawa Prefecture : 7.99 magnitude

Almost three times stronger than all calculations by TEPCO about the safety assessments for the plant. These were based on a magnitude 7.85 quake caused by a 131 kilometer long fault near Sado Island in Niigata and a 3.3 meter-high tsunami. To endure this, an embankment was under construction to resist tsunami waves up to 15 meters high. The recalculation could have consequences for the stress tests and safety assessments for the plant.[54]

After the planned revision of the safety standards in July 2013 some faults under the reactors might be considered as geologically active. This was found by a Japanese newsagency Kyodo News on 23 January 2013 in papers and other material published by TEPCO. Under the news regulations faults would be considered to be active when they moved in the last 400 000 years. Instead of the less strict 120 000 years formerly accepted. Two faults named “Alpha” and “Betha” are present under the reactors no.1 and no.2. Other faults are situated under reactor no.3 and no.5 as well as the building of reactor no.4. Under the new regulations the betha-fault could be classified as active because it moved a ground layer including volcanic ash around 240 000 years ago. The final outcome of the study might trigger a second survey by the newly installed Japanese regulator NRA. January 2013 studies were conducted or planned on geological faults around six Japanese reactor sites. The Kashiwazaki-Kariwa plant would be number 7. [55]” (References and more: http://en.wikipedia.org/wiki/Kashiwazaki-Kariwa_Nuclear_Power_Plant)

Seismicity and Japan’s Nuclear Reactors

Japan has had a long history of earthquakes and seismic activity, and destructive earthquakes, often resulting in tsunamis, occur several times a century. Due to this, concern has been expressed about the particular risks of constructing and operating nuclear power plants in Japan. Amory Lovins has said: “An earthquake-and-tsunami zone crowded with 127 million people is an un-wise place for 54 reactors”.[45] To date, the most serious seismic-related accident has been the Fukushima Daiichi nuclear disaster, following the 2011 Tōhoku earthquake and tsunami.

Professor Katsuhiko Ishibashi, one of the seismologists who have taken an active interest in the topic, coined the term genpatsu-shinsai (原発震災), from the Japanese words for “nuclear power” and “quake disaster” to express the potential worst-case catastrophe that could ensue.[46][47] Dr Kiyoo Mogi, former chair of the Japanese Coordinating Committee for Earthquake Prediction,[48] has expressed similar concerns, stating in 2004 that the issue ‘is a critical problem which can bring a catastrophe to Japan through a man-made disaster’.[49][50]

Warnings from Kunihiko Shimazaki, a professor of seismology at the University of Tokyo, were also ignored. In 2004, as a member of an influential cabinet office committee on offshore earthquakes, Mr. Shimazaki “warned that Fukushima’s coast was vulnerable to tsunamis more than twice as tall as the forecasts of as much as five meters put forth by regulators and Tokyo Electric”.[51] Minutes of the meeting on Feb. 19, 2004, show that the government bureaucrats running the committee moved quickly to exclude his views from the committee’s final report. He said the committee did not want to force Tokyo Electric to make expensive upgrades at the plant.[51]

Hidekatsu Yoshii, a member of the House of Representatives for Japanese Communist Party and an anti-nuclear campaigner, warned in March and October 2006 about the possibility of the severe damage that might be caused by a tsunami or earthquake.[52] During a parliamentary committee in May 2010 he made similar claims, warning that the cooling systems of a Japanese nuclear plant could be destroyed by a landslide or earthquake.[52] In response Yoshinobu Terasaka, head of the Nuclear and Industrial Safety Agency, replied that the plants were so well designed that “such a situation is practically impossible”.[52] Following damage at the Kashiwazaki-Kariwa Nuclear Power Plant due to the 2007 Chūetsu offshore earthquake, Kiyoo Mogi called for the immediate closure of the Hamaoka Nuclear Power Plant,[48][53] which was knowingly built close to the centre of the expected Tōkai earthquake.[49] Katsuhiko Ishibashi previously claimed, in 2004, that Hamaoka was “considered to be the most dangerous nuclear power plant in Japan”.[54]

The International Atomic Energy Agency (IAEA) has also expressed concern. At a meeting of the G8’s Nuclear Safety and Security Group, held in Tokyo in 2008, an IAEA expert warned that a strong earthquake with a magnitude above 7.0 could pose a ‘serious problem’ for Japan’s nuclear power stations.[55] Before Fukushima, “14 lawsuits charging that risks had been ignored or hidden were filed in Japan, revealing a disturbing pattern in which operators underestimated or hid seismic dangers to avoid costly upgrades and keep operating. But all the lawsuits were unsuccessful”.[56] Underscoring the risks facing Japan, a 2012 research institute investigation has “determined there is a 70% chance of a magnitude-7 earthquake striking the Tokyo metropolitan area within the next four years, and 98% over 30 years”. The March 2011 earthquake was a magnitude-9.[57]

Design standards

Horizontal acceleration experienced and design values during the 2007 and 2011 major earthquake and earthquake-tsunami events.
Between 2005 and 2007, three Japanese nuclear power plants were shaken by earthquakes that far exceeded the maximum peak ground acceleration used in their design.[58] The tsunami that followed the 2011 Tōhoku earthquake, inundating the Fukushima I Nuclear Power Plant, was more than twice the design height,[59] while the ground acceleration also slightly exceeded the design parameters.[60]

In 2006 a Japanese government subcommittee was charged with revising the national guidelines on the earthquake-resistance of nuclear power plants, which had last been partially revised in 2001,[61] resulting in the publication of a new seismic guide — the 2006 Regulatory Guide for Reviewing Seismic Design of Nuclear Power Reactor Facilities.[61] The subcommittee membership included Professor Ishibashi, however his proposal that the standards for surveying active faults should be reviewed was rejected and he resigned at the final meeting, claiming that the review process was ‘unscientific'[48][62] and the outcome rigged[62][63] to suit the interests of the Japan Electric Association, which had 11 of its committee members on the 19-member government subcommittee.[63] Ishibashi has subsequently claimed that, although the new guide brought in the most far-reaching changes since 1978, it was ‘seriously flawed’ because it underestimated the design basis earthquake ground motion.[46] He has also claimed that the enforcement system is ‘a shambles'[46][58] and questioned the independence of the Nuclear Safety Commission after a senior Nuclear and Industrial Safety Agency official appeared to rule out a new review of the NSC’s seismic design guide in 2007.[46]

Following publication of the new 2006 Seismic Guide, the Nuclear and Industrial Safety Agency, at the request of the Nuclear Safety Commission, required the design of all existing nuclear power plants to be re-evaluated.[64]“(References and more at link: http://en.wikipedia.org/wiki/Nuclear_power_in_Japan)

The Intensity Likely Felt at the Nuclear Power Stations:
IV. Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably.
V. Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop
Magnitude 4.0 – 4.9 Typical Maximum Modified Mercalli Intensity IV – V, http://earthquake.usgs.gov/learn/topics/mag_vs_int.php

[1] http://www.jma.go.jp/en/quake/20141122221916393-222208.html http://earthquake.usgs.gov/earthquakes/eventpage/usb000syza#summary
[2] “37 Homes Collapse, Dozens Injured in Japan Quake
By THE ASSOCIATED PRESSNOV. 22, 2014, 12:00 P.M. E.S.T.

6.8 Quake 22 Nov. 2014 Source: Japan Meteorological Agency website
Source: Japan Meteorological Agency website http://www.jma.go.jp/en/quake/20141122221916393-222208.html
(There is additional info at the website).

USGS Japan 22 Nov 2014 Felt Quake
USGS Distance from epicenter felt
distance from epicenter Nov. 22 2014 USGS http://earthquake.usgs.gov/earthquakes/eventpage/usb000syza#summary
(There are more maps and info at the USGS site)

1906 San Francisco Quake vid footage: