Tohoku Region Pacific Coast Earthquake Research Articles

Initial stiffness degradation and its effect on seismic capacity of shear wall with high reinforcement volume: An experimental study

Nuclear simulation analyses and field investigations were performed to study the seismic response of the reinforced concrete (RC) walls of the Onagawa NPP Unit 2 reactor building to the Tohoku Region Pacific Coast Earthquake on March 11, 2011 (hereafter referred to as the “March-11 Earthquake”). They indicated that the degree of deformation of the walls remained within the elastic range and did not reach the plastic range. Small residual cracks appeared in the shear walls on some floors, and the observation records of the natural period of the building exhibited stiffness degradation. In addition to the effect of large seismic loads, which are among the factors responsible for such reduced initial stiffness, a correlation between reduced stiffness and deterioration due to aging was recognized in the results of the analyses based on long-term earthquake observation records. The likely factors responsible for deterioration from aging include internal stress and cracks resulting from the drying shrinkage characteristics of concrete. Therefore, we conducted seismic resistance experiment #1, a static load test, to understand the effect of drying shrinkage on the initial stiffness and maximum strength. The results for the specimens subjected to drying showed better agreement with the results of the observation record analysis of the reactor building than those that were not subjected to drying. In addition, because small residual cracks occurred in the reactor building, we conducted seismic resistance experiment #2, a static load test, to understand the effect of such cracks on the ultimate strength and deformation capacity. The test confirmed that the seismic performance of the building after the earthquake was ensured. From the results of these investigations, it is considered that both the drying shrinkage of concrete and large seismic forces from the March-11 Earthquake were factors in the initial stiffness reduction of the Onagawa Unit 2 reactor building. However, there was no significant impact on the seismic performance of the building.

Transportation behaviour of radioactive substances in soils

In 2011, a number of radioactive substances were released as a result of the accident at the Fukushima Daiichi Nuclear Power Plant, Japan, which was caused by the Tohoku region Pacific coast earthquake. The radioactive substances that were released fell onto the surrounding ground and into the sea. Therefore, decontamination measures for the ground have been conducted at the field site. However, the safety and validity of modern decontamination measures were uncertain because no analytical verification had been performed that considered the various properties of the ground. Moreover, selection of the site where storage containers for radioactive materials could be constructed was a critical issue that required a solution. Therefore, it was necessary to evaluate quantitatively the behaviour of radioactive substances in soils to prepare new decontamination methods for the ground. In this study, the advection–dispersion equation was added to the radioactive half-life to evaluate the transportation of radioactive substances. As the results of this study show, this analytical method could recreate the on-site situation through comparison of the analysis results with the measurement results. Furthermore, modern decontamination techniques were effective for the section under analysis for ground with a silt or a clay layer. However, these techniques were not effective for sand layers.

Latest Trends of Transformer Bushing Seismic Analysis

SUMMARYIn Tohoku Region Pacific Coast Earthquake, many of the power equipment (especially center clamping type bushings for power transformers) were damaged due to the seismic motion that exceeds the design criteria. The problem of the conventional seismic analysis became clear as the actual damage was revealed. Since elaboration of seismic analysis and evaluation technology was called for, the elaboration possibility of seismic analysis was verified by carrying out comparison with various test results and the analysis result by the latest technique.

Dynamical Analysis of Stock Market Instability by Cross-correlation Matrix

We study stock market instability by using cross-correlations constructed from the return time series of 366 stocks traded on the Tokyo Stock Exchange from January 5, 1998 to December 30, 2013. To investigate the dynamical evolution of the cross-correlations, crosscorrelation matrices are calculated with a rolling window of 400 days. To quantify the volatile market stages where the potential risk is high, we apply the principal components analysis and measure the cumulative risk fraction (CRF), which is the system variance associated with the first few principal components. From the CRF, we detected three volatile market stages corresponding to the bankruptcy of Lehman Brothers, the 2011 Tohoku Region Pacific Coast Earthquake, and the FRB QE3 reduction observation in the study period. We further apply the random matrix theory for the risk analysis and find that the first eigenvector is more equally de-localized when the market is volatile.

Integrity Check of Tokai Reprocessing Plant after the Tohoku Region Pacific Coast Earthquake

Integrity Check of Tokai Reprocessing Plant after the Tohoku Region Pacific Coast Earthquake

Research on the Isolated Villages and Emergent Transportation Networks in Otsuchi Town Soon after Tohoku Region Pacific Coast Earthquake

Research on the Isolated Villages and Emergent Transportation Networks in Otsuchi Town Soon after Tohoku Region Pacific Coast Earthquake

Measurements of gamma (γ)-emitting radionuclides with a high-purity germanium detector: the methods and reliability of our environmental assessments on the Fukushima 1 Nuclear Power Plant accident

The severe accident of Fukushima 1 Nuclear Power Plant due to the Tohoku Region Pacific Coast Earthquake in 11 March 2011 caused wide contamination and pollution by radionuclides in Fukushima and surrounding prefectures. In the current JPR symposium, a group of plant scientists attempted to examine the impact of the radioactive contamination on wild and cultivated plants. Measurements of gamma (γ) radiation from radionuclides in "Fukushima samples", which we called and collected from natural and agricultural areas in Fukushima prefecture were mostly done with a high-purity Ge detector in the Graduate School of Maritime Sciences, Kobe University. In this technical note, we describe the methods of sample preparation and measurements of radioactivity of the samples and discuss the reliability of our data in regards to the International Atomic Energy Agency (IAEA) Interlaboratory comparisons and proficiency test (IAEA proficiency test).

Some Characteristics of Industries after the Tohoku Region Pacific Coast Earthquake on Minami-Soma City Haramachi Region, Fukushima Prefecture

Some Characteristics of Industries after the Tohoku Region Pacific Coast Earthquake on Minami-Soma City Haramachi Region, Fukushima Prefecture

Hazard Map of Housing Estates on Transformed Hills and Damage due to Tohoku Region Pacific Coast Earthquake

Hazard Map of Housing Estates on Transformed Hills and Damage due to Tohoku Region Pacific Coast Earthquake

Economic Damage Caused by Lowered Prices in the Agro-Food Sector in Areas Contaminated by Radioactive Materials Leaked from the Nuclear Power Plant Severely Damaged by the 2011 Great East Japan Earthquake

Large amounts of radioactive materials were leaked into the environment from the Fukushima Daiichi Nuclear Power Plant (FDNPP) of the Tokyo Electric Power Company, which was severely damaged by the 2011 Tohoku Region Pacific Coast Earthquake and accompanying tsunami. Economic damage due to lowered prices and supplies of food products produced in the areas contaminated by the radioactive materials leaked from the damaged FDNPP to the agro-food sector in the affected areas is notable. In Japanese, this is known as fuhyo higai. In this study, we investigated fuhyo higai from the viewpoints of epidemiology, economics, and social psychology in an effort to seek solutions. Information was obtained from articles in print and on the Internet. Fuhyo higai, or economic damage of the agro-food sector, which is the main industry in the contaminated areas, is serious because it is difficult to reassure the general population regarding food safety. This fuhyo higai does not derive solely from rumor. It has been reported that improving the science literacy of the general population is important as a countermeasure against fuhyo higai, but this may not be effective because of the human social structure and behavior of people who seek subjective safety. Almost all radiological laboratory results of samples of food produced in the contaminated areas were below detectable limits. Very high values were rarely detected. In general, information about the dose-response relationship is obtained under the assumption that there may be error in the response but not in the dose. The rare cases of extremely high radiological values of food samples from the contaminated areas may correspond to large errors in dose. However, it is difficult to deny a high-dose risk. The reported information on the dose-response relationship obtained under the assumption that there is no error in dose is not sufficient. Thus, response, i.e., health risk, cannot be correctly estimated. This leads the general population to choose food products from areas far from the FDNPP over those from the contaminated areas. In order to resolve this problem, thorough decontamination of radioactive areas, including large forests, is necessary for the market to regain competitiveness to the level it was before the accident. The cost of such decontamination is enormous and requires much labor. Decontamination will create employment and is indispensable in restoring the deteriorated economic conditions of the affected areas.

The Aftermath of the Tohoku Region Pacific Coast Earthquake Relating to the Hospital Information System in the Disaster Area

The Aftermath of the Tohoku Region Pacific Coast Earthquake Relating to the Hospital Information System in the Disaster Area

東日本大震災のスポーツへの意識および参加行動に対する影響

東日本大震災のスポーツへの意識および参加行動に対する影響

Review of thermal-hydraulic researches in severe accidents in light water reactors

The Tohoku Region Pacific Coast Earthquake and subsequent severe accident (SA) in Fukushima Daiichi Nuclear Power Station caused unprecedented disaster in Japan. Before this accident, considerable researches on SAs had been carried out in Japan. However, unfortunately, such researches could not prevent the accident due to the unexpected huge Tsunami. However, the researches on SAs become more and more important in order to make clear the causes of the accident in Fukushima and improve the safety of nuclear power plants in Japan. In view of this, review on researches on thermal hydraulics in SAs in light water reactors was carried out. Important thermal-hydraulic phenomena in SAs were identified. Research activities on each phenomenon were surveyed mainly based on the articles published in Journal of Nuclear Science and Technology of Atomic Energy Society of Japan.

A cluster of diffuse alveolar hemorrhage cases after the 2011 Tohoku Region Pacific Coast Earthquake

Diffuse alveolar hemorrhage (DAH) is a clinical syndrome that presents with progressively hemorrhagic bronchoalveolar lavage fluid (BALF) in serial samples and generally has a poor prognosis. The South Miyagi Medical Center, located on the inland side of southern Miyagi Prefecture, documented an increase in the number of patients with DAH after the 2011 Tohoku Region Pacific Coast Earthquake. We describe the clinical features of post-earthquake DAH in comparison to pre-earthquake DAH. We analyzed the data of the DAH patients we have been able to follow for at least 6 months since we started performing bronchoscopy and bronchoalveolar lavage (BAL) for all patients with interstitial lung disease in August 2009 until September 2011, and separated these patients into pre- and post-earthquake groups according to the earthquake date of March 11, 2011. Post-earthquake DAH patients tended to test positive for infectious agents and showed higher serum IgE titers, with BALF that exhibited a tendency to higher silica concentrations. Post-earthquake DAH generally had a better prognosis than pre-earthquake DAH. In describing the clinical features of post-earthquake cases of DAH, this report documents the possibility of an infection- and/or dust-induced, partially allergic, and relatively benign form of DAH.

Effectiveness of Liquefaction Countermeasures in the 2011 M = 9 Gigantic Earthquake, and an Innovative Soil Improvement Method

Along with damages caused by tsunamis, huge areas were affected by liquefaction at the wake of Tohoku Region Pacific Coast Earthquake. Demands seem to increase for seismic reinforcement on soils beneath existing structures not only for the devastated areas, but also for other places where seismic events are expected to occur in near future. In this paper, liquefaction countermeasures are first reviewed of which the authors were in charge during the site works. Restrictions for the works were highlighted to show how they were overcome. Effectiveness of the liquefaction countermeasures were also explained through observations at the projected sites. Finally, an innovative soil improvement method recently developed by the authors is introduced. The method consists of directional drilling and permeation grouting that can conduct soil improvement work beneath existing structures effectively and economically.

RADIATION MEASUREMENTS AT THE CAMPUS OF FUKUSHIMA MEDICAL UNIVERSITY THROUGH THE 2011 OFF THE PACIFIC COAST OF TOHOKU EARTHQUAKE AND SUBSEQUENT NUCLEAR POWER PLANT CRISIS

An earthquake, Tohoku region Pacific Coast earthquake, occurred on the 11th of March, 2011, and subsequent Fukushima nuclear power plant accidents have been stirring natural radiation around the author's office in Fukushima Medical University (FMU). FMU is located in Fukushima city, and is 57 km (35 miles) away from northwest of the Fukushima Daiichi nuclear power plant. This paper presents three types of radiation survey undertaken through the unprecedented accidents at the campus and the hospital of FMU. First, a group of interested people immediately began radiation surveillance; the group members were assembled from the faculty members of " Life Sciences and Social Medicine" and " Human and Natural Sciences." Second, the present author, regardless of the earthquake, had serially observed natural radiations such as gamma radiation in air with NaI scintillation counter, atmospheric radon with Lucas cell, and second cosmic rays with NaI scintillation. Gamma radiation indicated most drastic change, i.e., peak value (9.3 times usual level) appeared on March 16, and decreased to 1.7 times usual level after two months. A nonlinear least squares regression to this decreasing data gave short half-life of 3.6 days and long half-life of 181 days. These two apparent half-lives are attributed to two groups of radioisotopes, i.e., short half-life one of I-131 and long half-life ones of Cs-134, Cs-137 and Sr-90. Also, atmospheric radon concentration became high since a stop of ventilation, while second cosmic rays did not show any response. Third, late April, 2011, a team of radiation dosimetry under the direct control of Dean, School of Medicine, was established for the continuation of radiation survey in the campus and the hospital of Fukushima Medical University.

Sand boils along the Naruse River and the Yoshida River by the 2011 Tohoku-Region Pacific Coast Earthquake

4月3日から5日にかけて，東日本太平洋沖地震における地震被害把握のために宮城県の中部に位置する鳴瀬川および吉田川の河川堤防の調査を行い，液状化した14地点の噴砂から試料を採取し，粒度試験を行った。ここでは，噴砂地点の記録と粒度試験の報告をする。噴砂地点は，旧河道などの自然地盤，ないしは河道を埋め立てた自然地盤が大部分である。また，平均粒径Ｄ50と均等係数Uを試料採取地点と河口からの河川経路に沿った距離で整理したところ，相関性が見られた。

3）被災地の食事の現状と栄養問題―東日本大震災被災地報告（宮城県気仙沼市）―

3）被災地の食事の現状と栄養問題―東日本大震災被災地報告（宮城県気仙沼市）―

東日本大震災前後のテレワーク相談センターへの相談者の変化(S3.テレワーク協会セッション,セッション部門,「中小企業のためのテレワーク」及び「震災とテレワーク」)

東日本大震災前後のテレワーク相談センターへの相談者の変化(S3.テレワーク協会セッション,セッション部門,「中小企業のためのテレワーク」及び「震災とテレワーク」)

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