The 11 March 2011 Tohoku, Japan Earthquake caused widespread devastation in the eastern Japan. Crustal movements larger than 5 m were observed on the land after the earthquake. In this study, a method to grasp the surface movement from pre- and post-event TerraSAR-X intensity images was proposed. Since the shifts of non-changed buildings between the two SAR images can be seen as the crustal movements, firstly the buildings in the pre- and post-event images were extracted by a segmentation approach. Then non-changed buildings were detected by matching the buildings in the pre- and post-event images at similar locations. Finally, the shifts were calculated by area-based matching. The method was tested on the TerraSAR-X images of Tohoku region and central Tokyo, and the accuracy was verified by the observed data from GPS ground stations.

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This paper presents and analyzes the identified vibration characteristics of steel high-rise building built at Shinjuku. The vibration characteristics, i.e.; natural periods, damping coefficients and participation functions, are identified from the measured acceleration during the some earthquakes including the mainshock of the 2011 off the Pacific coast of Tohoku Earthquake. The curve-fitting method using the transfer function is applied in the identification. The change in natural period before and after the earthquake and the dependency on the modal amplitude are clear. The damping coefficients for the 1^st and 2^nd modes are found to be unexpectedly smaller than 0.02, that has been conventionally assumed in design of steel buildings.

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Some of existing low earthquake resistant RC buildings were severely damaged by The 2011 off the Pacific coast of Tohoku Earthquake. The objective of this study is to evaluate the structure performance and the damage levels of the existing RC buildings damaged by the earthquake in Ibaraki. By comparing observed damage levels with results of seismic evaluation method, it was confirmed that the seismic performance was influenced by concrete strength decrease due to shoddy workmanship and concrete block wall.

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The 2011 off the Pacific Coast of Tohoku Earthquake stroke very vast area of east side of Japan, and they greatly talked about tsunami-related information, but it seems not so much about the earthquake damage to a buildings (especially reinforced concrete buildings). In this report, the tendency of suffering a calamity of the precast concrete buildings built in a stricken area was analyzed statistically from the collection of the results of investigation carried out in many organizations after March 11, 2011 which the earthquake generated.
Data of the precast concrete buildings currently collected are 808 including the 95 buildings which performed anti-seismic reinforcement using precast concrete members.
By analyzation, it was checked that numbers of the precast concrete buildings had no or slight damages and there were very few precast concrete buildings which suffered the moderate or more serious damages.

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The 2011 off the pacific coast of Tohoku Earthquake caused severe liquefaction in the wide range of the reclaimed lands along Tokyo Bay. Especially 85 % of city area liquefied in Urayasu City. The authors conducted field survey in Urayasu City immediately after the earthquake. Several months after the earthquake, the authors sent out questionnaires to about 55 inhabitants to ask the timing of boiling, height of boiled muddy water and others. In addition, model tests were carried out to demonstrate the mechanism of boiling. By these investigations, it was concluded that boiling was accelerated due to the aftershock which occurred 29 minutes later, and more severe liquefaction occurred during the aftershock at some sites. Moreover, starting time of the boiling of muddy water are quite different at place. Depth of water table affected on the starting time.

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 This paper describes the dynamic response characteristics of 14 super high-rise residential buildings in the Kanto and Kansai areas on the basis of the recorded motions during the main shock of the 2011 off the Pacific coast of Tohoku Earthquake. In the Kanto area, the peak accelerations at the 1st floors or basements were around 100 cm/s². They were amplified by two to four times at the top floors. Structural responses in buildings constructed in the bayside area were greater than those in other areas because ground motions were amplified in the soil including soft surface layers. The building located in the Tokyo bayside area experienced the largest interstory drift angle of 1/170 rad. The natural frequencies gradually diminished as the structural response increased from its initial level. The natural frequency was reduced by about 20-40% by the time the relative displacement reached its peak and the reduced frequencies never recovered to their initial level. Bi-linear properties are inferred from the equivalent force-displacement relationship evaluated from the frequency ratio data.

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A long period ground motion during an earthquake sometimes has a serious impact on large structures. Since the ground motion during an earthquake is largely affected by the so-called site effect which is determined by the soil structure, it is important to obtain its profile, especially the shear wave velocity profile. In this study, an attempt has been made to estimate an shear wave velocity profile by seismometer array measurements during the 2011 Tohoku earthquake and its after shocks in addition to the earthquakes prior to it, in which Chiba City was chosen as a target area. The result was compared with that of microtremor measurement and the existing profile for deep soils. It was found from the study that the phase velocity dispersion curve obtained from earthquake observations overlaps smoothly with that from microtremor measurements. It was also found that, although the estimated soil profile has a fairly good agreement with the previously reported ones, there is a possibility of a slight underestimation of the previously reported ones when compared to our result.

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The applicability of peak acceleration ratio that has been proposed by authors as an index for characteristics of earthquake spectrum is verified by using earthquake motion records obtained during the 2011 off the Pacific coast of Tohoku Earthquake. We also try to use the peak acceleration ratio for evaluation of response of wooden houses. A relationship between the peak acceleration ratio and amplitude characteristics of Fourier spectrum of earthquake ground motion is estimated at observation sites with JMA seismic intensity of more than 5-. As a result, the ratio is useful to estimate an index of earthquake ground motion with a period range between 1 and 2s. Moreover, a relation between the peak acceleration ratio and drift angle of wooden houses evaluated by an equivalent-performance response spectrum is also examined. A good correlation is shown in case of 0.3 and 0.5 of the base shear coefficients of wooden houses.

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We investigated the strong ground motions and the damage of buildings near the surface faults of the 2011/04/11 Fukushima-ken-Hama-Dori earthquake (Mw 6.6). First, we confirmed that the strong ground motions from this normal fault were equivalent and/or more than the thrust fault, by using the strong motion records and the attenuation curves. We also checked that the ground motions near the surface faults were larger than those of the 2011/03/11 Great Tohoku earthquake (Mw 9.0), and therefore, the most of building damage was caused by the Fukushima-ken-Hama-Dori earthquake. Next, we investigated that the 191 buildings near the surface faults (within 500 m), and obtained the following conclusions. The most of severe damage was caused by the surface faulting and the subsequent ground failure. Among 9 buildings above the surface faulting, only one building was overturned. The building was a tall gate in a Budhism temple and fell on the side by the surface fault of 60 cm dislocation, because the columns were not anchored to the foundations. As for the other buildings, the damage by the strong ground motion was negligible. That is, the rate of heavy damage (Damage Grade 4 and upper) was less than 2%, which corresponds to JMA Intensity 5- and 6+, even though the most of buildings seemed very old and weak.

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Many aftershocks were observed in the Pacific coast of Tohoku Earthquake. In view of this fact, aftershocks should be paid attention, although it is ignored in the conventional design method. In this paper, the effect of aftershocks to buildings is discussed focusing attention on the energy input especially. From the cumulative energy spectrum, it is elucidated that aftershocks recorded this time has enough energy to bring certain degree of damage. P-Δ effect degrades the strength of the buildings virtually. Therefore, the building damaged after main shock can be brought significant incremental deformation by small energy of aftershocks.

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Site amplifications around the KiK-net strong motion station at Haga (TCGH16) in Tochigi prefecture were investigated from earthquake observation and microtremor array exploration in order to understand the characteristics of the strong ground motion recorded during the 2011 off the Pacific coast of Tohoku Earthquake with a seismic intensity of 7 in the intensity scale by Japan Meteorological Agency. We temporarily installed 8 seismometers within 2km around the strong motion site to obtain aftershock records in a few days in May, 2011. The spectral ratios at each site to that of a reference site were derived from the aftershock records. They are commonly characterized by an existence of a dominant peak at periods of 0.2 to 0.3 seconds. A similar dominant peak can be also identified in the weak-ground motion spectra at the TCGH16 station, suggesting significant effects of shallow soil layers. Then we revealed S-wave velocity profiles of the shallow soils down to a depth of about 30 meters over the engineering bedrock having an S-wave velocity of 400 m/s from the microtremor array explorations at all the aftershock observation stations. The S-wave velocity profiles are not significantly different at the stations within several hundred meters around TCGH16. The similar dominant peaks can be seen in the one-dimensional amplification factors of S-waves calculated for the profiles of the shallow soils at the aftershock stations around TCGH16. It is clearly indicates that the strong ground motion records at the KiK-net Haga station during the main shock can be regarded as representative one in the surrounding area.

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In order to understand the effects of strong ground motions on engineering structures, it is important to evaluate the effects of soil nonlinearity on strong ground motions. In this paper, based on strong motion records obtained in wide area during the 2011 Off the Pacific Coast of Tohoku earthquake, degree of soil nonlinearity was evaluated based on the shift of peak frequencies from linear site amplification factors to observed Fourier spectra during the Tohoku earthquake. Then, the relation between the degree of soil nonlinearity and ground motion indices such as PGA, PGV and PSI was investigated. It was found that the degree of soil nonlinearity was best correlated with PGV and the relation can be approximated with a hyperbolic curve. In addition, it was found that the deviation from this empirical formula is correlated with the peak frequencies of linear site amplification factors.

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This paper analyzes the commuters' behavior under the 2011 off the Pacific Coast of Tohoku Earthquake. Authors conducted web based questionnaire survey to collect the data. Respondents of the survey were limited to the people who had difficulty in going home on that day. And authors conducted interview survey for university and hospital staffs. As a result of this analysis, many commuters go to home through the dangerous zone which are fire zone and building damage zone.

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This The damage investigation of the damaged area of Sanriku railway and interview survey for Sanriku railway were executed due to the 2011 off the Pacific Coast of Tohoku Earthquake. As result of interview survey, Sanriku railway has huge damage of whole line by Tsunami. It became clear that people who live in around sanrikur ailway has request to recover the railway as soon as possible.

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A Railway Company's valuation was reduced by ¥ 23.6 billion by the 2011 off the Pacific coast of Tohoku Earthquake. The effect of seismic earthquake insurance risk transfer is equivalent to 65 billion yen. To decision-making earthquake insurance, CAT bond, seismic reinforcement of investment, it is necessary to evaluate the financial impact after the earthquake.

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Strong ground motions in the frequency range from 0.2 to 1 Hz observed at many sites along the coast of Miyagi through Ibaraki Prefecture during the 2011 off the Pacific coast of Tohoku earthquake are characterized by distinctive pulses. These strong motion pulses are similar to those from shallow crustal earthquakes in a sense that they appear in a frequency range of engineering importance. Because strong motion pulses from huge subduction earthquakes can also cause significant damage to structures, it is significantly important to consider the generation of such pulses in the strong motion prediction for huge subduction earthquakes, especially when the prediction is aimed at seismic design of structures. In this article, first, examples of strong motion pulses from huge subduction earthquakes are examined. Then, source models aiming at the reproduction of those pulses are compiled and the characteristics of SPGAs (Strong-motion Pulse Generation Areas) are investigated, with special attention to their relation to the size of the earthquakes.

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The Great East Japan Earthquake with a moment magnitude 9.0 occurred on March 11, 2011 and shook almost the entire Japan. There are many abandoned lignite mines in the close vicinity of the epicentral areas such as Miyagi and Iwate prefectures and many sinkholes occurred following the earthquake. There are also reports on the delayed occurrence of numerous sinkholes in the same areas. In addition, some collapses and subsidence occurred above abandoned underground quarries in Oya town of Utsunomiya City. The authors investigated damaged areas soon after the earthquake and they present their investigation results. They also discuss their implications in short and long-term performance of abandoned mines and quarries possible counter-measures against collapses in this article.

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The 2011 Tohoku, Japan earthquake caused extensive liquefaction to the coastal area of the Tokyo Bay and to the lower banks of the Tone River in North Kanto region. Since underground water pipeline is pulled out at the joint part due to the liquefied ground deformation, the number of pipeline damage would be an indicator of the liquefaction severity. Referring to the analysis of pipeline analysis in the Kashima region along the lower banks of the Tone River, the pipeline damage was not homogeneously distributed but concentrated locally in the size of 1 km². This study analyzes this concentration area from the landform and land use change. The damage concentration area was able to be clarified by using the old topographical maps compiled in 1880's though it was difficult to specify it by present topographical maps.

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After the Great East Japan Earthquake, importance of evacuation from tsunami is increasingly acknowledged. The authors conducted two types of questionnaire surveys of residents' evacuation in Onjuku, Chiba focusing on an estimated tsunami in 2008, and on the event in 2011. Then acquired evacuation spatial data are compared in terms of altitude, distance from the coastal line, and the number of people in the inundated area. As a result, the actual evacuation activities in comparison with the estimated showed (1) diversity, (2) numerous uses of cars, (3) longer distance, and (4) more people in the inundation area.

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Severe human damage occurred by Tsunami during The Great East Japan Earthquake. The number of refugees in Sendai city was approximately a hundred thousand at the peak. Not only refugees from the coast area but also persons unable to return home in the urban area were included in the number. The purpose of this study is to clarify the regional characteristics of occurrence including transition of refugees in Sendai city during this disaster. The distribution of the concentrated receive zone of refugees from the coast area and the occurrence zone of persons unable to return home in the urban area was clarified based on analytical results by using refugees data of Sendai fire defense bureau. Long-term use of a shelter gives quite a few troubles to education because many schools are specified as a shelter for refugees. By considering the regional characteristics of occurrence including transition of refugees to the public disaster prevention planning, the reduction of educational function in school and the expansion of secondary damage in shelter should be prevented against future mega earthquake disaster with tsunami.

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In this paper, according to the survey, it was able to grasp reality of High-rise building-specific damage that occurred at the Great East Japan Earthquake, initial response of regional businesses, and unable to return to home support. In addition, we proposed efforts to improve collaboration with local communities disaster prevention to clarify the challenges of the future based on the actual situation for the region to minimize the disruption of large-scale earthquake.

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We try to carry out the tsunami simulation using the displacement field of oceanic crustal movements, which is calculated from the ground motion simulation of the 2011 off the Pacific coast of Tohoku Earthquake. First, the large-scale ground motion simulation based on the voxel type finite element method is performed for the whole eastern Japan. The fault model based on the teleseismic body wave is assigned to the source region. Next, the tsunami simulation is performed by the finite difference calculation based on the shallow water theory. The initial wave height for tsunami generation is estimated from the vertical displacement of ocean bottom due to the crustal movements, which is obtained from the ground motion simulation mentioned above. Although the results of tsunami simulation show that synthetic waveforms are fairly consistent with the observations of the GPS wave gauges, the comparisons of synthetics and observation show that the tsunami simulation in this study underestimates the maximum wave height in most observing stations.

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This paper presents damage of bridges during the 2011 Great East Japan earthquake. Since the bridges in the north Miyagi-ken and south Iwate-ken suffered extensive damage in the 1978 Miyagi-ken-oki earthquake, damage of bridges in the 2011 Great East Japan earthquake is evaluated in comparison with the damage in the 1978 Miyagi-ken-oki earthquake so that effect of the recent progress of seismic design can be evaluated. Tsunami-induced damage was extensive for bridges along the Pacific Coast. Typical feature of tsunami-induced damage is presented based on a field investigation and video movies.

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Based on the DCRC strong-motion records in Sendai, site amplification characteristics in Sendai city during the 2011 Tohoku earthquake sequences are investigated. It is found that short-period (less than 1s) amplifications are predominant at northwestern area, while not only short but also long-period (around 3s) amplifications are predominant at southern area of Sendai. Such spatial differences are generally explained by the existing subsurface structure models, except that the backfilled soil model may be necessary to change and long-period later phase cannot be well explained in the southern area of Sendai.

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We revise the empirical relations for acceleration response spectra and average and variance of group delay time of long-period ground motions. The Mw² term is added in the revised relation for response spectra. In addition the differences between the Pacific plate earthquakes and the Philippine Sea plate earthquakes are considered into their attenuation and the site coefficients. We set the 3-connected source model composed of three outer-faults based on strong motion generation areas of the Tohoku earthquake. Finally we show that the long-period strong motions of the Tohoku earthquake are reasonably simulated well using the revised attenuation relations and the 3-connected source model.

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During the 2011 off the Pacific coast of Tohoku Earthquake, Naka-River Aqueduct, Ibaraki Prefecture, Japan, suffered significant damage including pipe dropout in expansion joints. In this study, to estimate strong ground motions at the damage site with high accuracy, aftershock observations with a dense array were conducted at the site. Based on the observation records, difference of site effects between the landside area and the riverside area was indicated. The estimated seismic waveforms at permanent strong motion stations with the site-effect substitution method are very consistent with the observed ones, indicating the validity of the method. Finally, the method was used to estimate strong ground motions at the damage site.

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In this study, the authors developed a damage evaluation method in terms of a damage spectrum that represents the relationship between the damage index DI of the entire building and the natural period of the building. The DI values obtained from the damage spectra were compared with the damage levels of RC Buildings affected by the Great East Japan Earthquake. As a result, the DI values and the damage levels showed good correspondence for the buildings in accordance with the old seismic standards. On the other hand, as for the buildings in accordance with the new seismic standards, it was found that an effect of overstrength on DI value of buildings should be considered. Furthermore, it is suggested that the present method may enable to make seismic evaluation considering the impact of aftershocks feasible.

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We clarify the seismic response of coupled long-period structures with Maxwell-type dampers subjected to long-period ground motions. The simulated long-period ground motions induced in anticipated Nankai earthquake are used for analyses. By varying damping coefficient c_m and stiffness k_m of dampers, the minimal relative displacements for 2DOF systems are computed to analyze the dependence of long-period components of the ground motions on the effectiveness of optimal structural control by installing dampers from view of five points : frequency ratio ω_f/ω^s₁ defined as the value of dominant angular frequency of a ground motion ω_f compared with 1st natural angular frequency of the systems ω^s₁ , mass ratio μ (m₂/m₁), frequency ratio γ (ω₂/ω₁) defined as the ratio of natural angular frequency for system 2 ω₂ by that for system 1 ω₁, stiffness ratio of dampers n defined as the ratio of damper's stiffness k_m by system 1's stiffness k₁ and damping ratio ζ defined as the ratio of damping coefficient c_m by system 1's damping coefficient. Furthermore, we analyze long-period components of the ground motions recorded at 506 K-NET and KiK-net stations in the 2011 off the Pacific Coast of Tohoku earthquake, which are possible to affect seismic response of coupled long-period structures with Maxwell-type dampers.

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