The tsunami caused by the 2011 Tohoku earthquake resulted in a severe accident at the Fukushima Daiichi nuclear power plant (NPP). In light of analysis of the generation mechanisms of the earthquake and tsunami, a tsunami source model is inferred and further verified by the seismic source model inferred from ground motions.Distribution of large slip in the area along the Japan trench is a common finding obtained from both models.Through simulation analysis of the observed tsunami at the NPP sites, it becomes clear that the large slip in the shallow area along the Japan Trench, the time difference of rupture propagation, and the time delay of tsunami propagation are the main factors that significantly affect the tsunami heights.

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After disastrous earthquakes, estimating building damage levels objectively and quantitatively is very necessary and important for making decisions of buildings to be continuously used, repaired or demolished. The decline of natural frequency of buildings can be used to estimate the damage condition of the whole building quantitatively. However, in order to scrutiny building damage of inner stories, the deliberation on natural frequency is not enough. Therefore, in this paper, a method to estimate shear-wave velocity traveling within stories from microtremor records is presented. Using the presented method, shear-wave velocity traveling within a damaged 9-story SRC residential building is extracted, based on which damage condition of this building is evaluated.

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The Great East Japan Earthquake did not damage any important facilities used by Tokyo Gas for city gas production and supply operations, but some low pressure pipelines with low earthquake resistance were damaged, forcing the company to suspend supplies of gas to about 30,000 homes to preserve safety. This report briefly describes Tokyo Gas's response to the Great East Japan Earthquake, which is centered on the super-dense real time monitoring earthquake system. And, it verifies about the accuracy of pipeline damage estimation.

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A 9-story steel frame reinforced concrete building in Sendai was severely damaged during the 2011 Great East Japan Earthquake. Fortunately, two seismometers were emplaced at the 1^st floor and the 9^th floor, and the whole earthquake records were observed during this earthquake. The nonlinear response analysis of the building is simulated which based on the elastic plastic properties of constituent structural elements during the earthquake. And a partial uplift phenomenon between the 2^nd floor and the 3^rd floor which observed is confirmed by the simulation analysis.

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Many people in the metropolitan area were difficult to return home for railroad suspension in the Great East Japan Earthquake. This paper reports results of questionnaire survey on behavior of students and university faculties in Tokyo University of Science for returning home in the Great East Japan Earthquake. From findings, when the earthquake disaster occurred, large majority of students selected to stay at school. On the other hand, university faculties tended to relatively return home. The return means had most foot. The return distance is distributed a lot over approximately less than 15km. Persons who try to reach home on foot decreased as home is far, but examples that came home on foot beyond 30km were appeared.

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The 2011 off the Pacific coast of Tohoku earthquake of 11 March 2011 occurred along the subduction zone plate boundary between the Pacific and North American plates along the Japan Trench. This earthquake caused the Great East Japan Earthquake Disaster. In this study, we try to estimate the source model by a forward-modeling approach based on the characterized source model using the empirical Green's function method. Based on the results, we proposed a source model composed of five strong motion generation areas (SMGAs) along the subduction zone plate boundary. The SMGAs were located in the sea off Miyagi Prefecture, south Iwate, Fukushima and Ibaraki Prefectures. Comparing synthetic waveforms calculated by the empirical Green's function method and the observed waveforms, it can be seen that the observed waveforms are well reproduced at each observation station. The total seismic moment of SMGAs is 5% of the seismic moment determined by the Japan Meteorological Agency.

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[in Japanese]

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