BUILDING RESEARCH INSTITUTE The Great East Earthquake Damage Report The Building Research Institute of Japan has conducted an extensive survey of the damage caused to buildings and homes by seismic motion and tsunami waves during the 2011 Great East Japan Earthquake, and offers this report. (Detailed data including damage due to tsunami: http://www.kenken.go.jp/english/ index.html) To obtain technical Figure 1: Distribution of slip amount data to be used in a re- on the fault estimated from tsunami view of technical stan- measurements (Fujii et al:, 2011, dards in light of the Earth, Planets and Space) earthquake, after the earthquake struck the Building Research Institute (BRI) and the National Institute for Land and Infrastructure Management (NILIM) set about the task of collecting information on damages due to seis- mic movement and the tsunami waves, focus- The tsunami swept away all the wooden and low-rise build- ing primarily on build- ings in this coastal area of Onagawa, , ing structures. except for a solitary reinforced concrete building. The shaking expe- rienced around the t 2:46 p.m. on March 11, country is important information through 2011, what is formally known which we can understand the structural as the “2011 off the Pacific damage caused by the earthquake. To A coast of Tohoku Earthquake” look at this, we will introduce strong mo- struck, with an epicenter off the coast of tion seismograms recorded in the disas- . Casualties from the disaster ter-affected regions, which were obtained stand at 15,839 fatalities and 3,642 miss- through the strong-motion earthquake area from Hokkaido to western Japan. ing. Damage to buildings includes observation project conducted by the As the earthquake occurred along what 120,241 buildings completely destroyed, BRI. The epicentral area of this earth- is known as a plate boundary, the rup- 189,822 buildings partially destroyed quake was extremely large, and regions tured epicentral area was large, and the and 598,587 buildings partially damaged experiencing strong motion occurred resultant aftershock area is estimated to (announced by the National Police across the widest area ever seen. have been around 500 km to the north Agency as of November 17, 2011). While buildings also suffered dam- and south, and around 200 km to the While the size of the earthquake age, buildings constructed according to east and west. The seismic rupture was reported as magnitude 7.9 by the the new earthquake resistance standards began around the area indicated by the Japan Meteorological Agency immedi- did not suffer major damage. In light of symbol in Figure 1, and according to ately after it struck, on March 13 this lessons learned from earthquake damage BRI analysis, the largest slip amount of was revised to 9.0 (on the moment mag- due to the 1978 Miyagi earthquake and about 48 meters occurred in the vicinity nitude scale). An earthquake of this size others, Japan strengthened its seismic of the ocean trench where the plate was Japan’s largest in recorded history, design standards in accordance with the boundary is located. It is also estimated and the scale of damage it caused was Building Standards Law and related that between 10 and 30 meters of slip also greater than ever experienced. ordinances from June 1981. These stan- amount occurred from off the coast of The tsunami waves that arrived dards are known as the new earthquake Miyagi Prefecture to the southern along the coast shortly after the earth- resistance standards. Sanriku Coast, approximately ten meters quake hit reached far inland over a vast off the Fukushima coast and roughly area from in the Large Epicentral Area two meters off the coast of Ibaraki north to in the south, Prefecture. Off the central Sanriku coast, resulting in immense damage. The earthquake was felt across a wide slip amount of between five and eleven

22 The Japan Journal DECEMBER 2011 The Japan Journal DECEMBER 2011 23 Figure 2: Distribution of seismic Figure 3: Records obtained from BRI Figure 4: BRI strong motion observation intensity for each region during the strong motion observation stations stations in the Tokyo metropolitan area main shock

meters is estimated in some areas. were felt across almost all of Japan. the building at the time. This is easy if The symbol in Figure 1 indicates the seismic observations are conducted in *1 K-NET: A ground-based strong-motion starting point of the rupture which rep- earthquake observation network installed buildings. The BRI conducts seismic resents the beginning of the earthquake. across Japan by the National Research observations targeting buildings at ap- From this point the rupture widened as Institute for Earth Science and Disaster proximately seventy locations nation- Prevention and the system which transmits far as off the coast of to strong-motion recording data via the Internet. wide with the aim of measuring the the north and to the *2 Gal: Unit of acceleration (1 gal earthquake resistance of buildings. south, resulting in a vast epicentral area. = 1 cm/s2) Figure 6: Characteristics of seismic movements Widespread Shaking The seismic intensity in disaster-affected regions (inside buildings). readings shown in Figure 2 The stated level is exceeded at 2 and 3 seconds In Japan, the size of earthquake shocks is are calculated from ground- into the cycle, but this is not a problematic level. expressed in terms of the Japan based observation records. Damping Ratio: 5% Akita Prefectural Office B1F Meteorological Agency (JMA) Seismic Seismic movements vary not Hachinohe City Hall GL Iwaki City Hall B1F Intensity Scale. The largest seismic inten- only according to the size of Miyako City Hall GL Niigata City Hall B1F sity recorded during the 2011 earthquake an earthquake and the dis- Sendai Government Office Building B2F Design Level on Bedrock was level 7 at the Tsukidate station in tance from the epicenter, but Kurihara, Miyagi Prefecture. No other also due to ground conditions areas recorded level 7 intensity. at the observation point. However, in terms of peak ground accel- To determine whether a (cm/s) eration, which is an alternate indicator of building is resistant to earth- shaking used by strong motion observa- quakes, it is important to de- tion networks operated by other agencies termine not only the response such as K-NET*1, this measurement sur- of the building during an Response Pseudo Velocity passed 1,000 Gal*2 at many observation earthquake, but the seismic Period (seconds) stations. As Figure 2 shows, the shocks motions which acted upon Figure 7: Seismic motion characteristics at obser- vation stations in the Tokyo metropolitan area Figure 5: Comparison of observed waveforms (velocity waveforms) (first floors, basement floors or ground surface) for the same building during the 1978 Earthquake off the Coast of Educational Center, Funabashi City GL Miyagi Prefecture (blue) and the 2011 Earthquake off the Pacific Damping Ratio: 5% Gyotoku Library, Ichikawa City 01F Central Government Building No. 6 01F coast of Tohoku (black) Sumida Ward Office B1F 37-story High-rise Residential Building, Chuo Ward 01F June 12, 1978 Off the Coast of Shinagawa International House, Tokyo University Miyagi Prefecture Earthquake of Marine Science and Technology Design Level on Bedrock (cm/s) Velocity (cm/s) Velocity

March 11, 2011 Off the Pacific Coast of Tohoku Earthquake Pseudo Velocity Response Pseudo Velocity

Time (seconds) Period (seconds)

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Table 1: Main strong motion records obtained by BRI was large, and since there was a long time Max. Acc. (cm/s2) from the start to end of rupturing at the Code Station Name _ (km) IJMA Loc. H1 H2 V epicenter, the shocks felt in all regions Sendai Government Office B2F* 163 259 147 SND 175 5.2 continued for longer than ever before. Bldg. No. 2 (high-rise) 15F 361 346 543 Table 1 shows the instrumental inten- 01F* 333 330 257 Tohoku University Civil Engineering and THU 177 5.6 sity, directional peak acceleration, etc. of Architecture Bldg. 09F 908 728 640 the shocks recorded at major observation 01F 138 122 277 stations during the 2011 earthquake. MYK Miyako City Hall 188 4.8 07F 246 197 359 Of these stations, the Civil GL* 174 174 240 B1F* 175 176 147 Engineering and Architecture building IWK Iwaki City Hall 210 5.3 09F 579 449 260 (ninth floor) at Tohoku University, A01* 279 227 248 which recorded a large velocity response A89 142 153 102 during the 1978 off the coast of Miyagi BFE 194 191 136 ANX Building Research Institute 330 5.3 8FE 597 506 344 Prefecture earthquake, also obtained a MBC 203 206 152 large recording this time. However, M8C 682 585 311 from the comparison of their respective B3F* 74 63 42 Figure 5 Saitama Shintoshin Government velocity waveforms shown in SIT2 378 4.4 10FS 119 138 62 Office Building No.2 Annex (high-rise) we can see that the 2011 earthquake was 27FS 248 503 107 much longer than the 1978 earthquake. Saitama Shintoshin SITA Government Office Building, Public 378 4.5 01F* 90 105 47 In Figure 6, we compared the pseudo Welfare Building velocity response spectra that indicates GL* 265 194 150 the cyclical size of seismic motions for National Museum of Western Art B1FW 100 79 84 NMW 382 4.8 (base-isolation) 01FW 76 89 87 buildings in the main disaster-affected 04F 100 77 90 regions of Sendai, Iwaki, Miyako and 01F* 90 86 45 Central Government Office Bldg. No.6 Hachinohe. The observations were re- CGC 386 4.4 (high-rise) 20B 208 148 173 corded at building ground level, base- 19C 179 133 130 B4F* 75 71 49 ment level or on the ground. For be- Central Government Office Bldg. No.2 CG2 386 4.2 13F 137 113 72 tween two and three seconds of the (high-rise) 21F 121 131 104 cycle, the observations slightly exceeded B2F* 104 91 58 Central Government Office Bldg. No.3 the Building Standards Law design CG3 386 4.5 B1F 55 41 62 (base-isolation) spectra level for engineering bedrock, 12F 94 82 104 B8F 61 88 53 but not by such a large margin. In addi- B4F 68 101 56 tion, observations in the long-period NDLA Annex, Library 387 4.5 01F* 76 104 84 areas were not especially large. 04F 125 192 94 Also note that at Miyako City Hall, 01F* 35 33 80 18F 41 38 61 the government building was inundated Sakishima Office, Osaka Prefecture SKS 770 3.0 38F 85 57 18 to the second floor. Since the recording (high-rise) 52FN 127 88 13 device for seismological data was on the 52FS 129 85 12 top floor of the government building, we Note: _: epicentral distance; IJMA : instrumental seismic intensity (calculated from records of acceleration of were able to retrieve the data. three components according to JMA method using asterisked sensor); Installation azimuth: clockwise direction from North; H1, H2, V: maximum accelerations in horizontal #1 (Azimuth), horizontal #2 (Azimuth + 90°) and Figure 7 shows the pseudo velocity vertical directions. A01: Ground surface A89: 89m underground response spectra indicating the cycli- cal size of seismic motions for the ob- In Japan, strong-motion earthquake Office Bldg. No. 2 (SND), Tohoku servational data obtained in buildings observations began in 1953. The BRI University (THU) and Iwaki City Hall in the major areas of the Tokyo metro- has also conducted building observa- (IWK) show high levels. In particular, politan area. tions over a long period that dates back the reinforced concrete structure of the Even in the Kanto region, K-NET to this time. Figure 3 shows which of the Civil Engineering and Architecture build- and other networks observed extremely current BRI observation stations record- ing at Tohoku University was damaged strong shaking at some stations in the ed measurements during the 2011 earth- and has been rendered unusable. At the prefectures of Ibaraki, Tochigi and Chiba. quake. As shown in Figure 4, the obser- time of the 1978 Miyagi earthquake that However, observation values in the vation stations are more densely struck in June 1978, acceleration of more Tokyo metropolitan area itself were not arranged in the Tokyo metropolitan area. than 1G was recorded on the ninth floor that large. Table 1 shows the instrumental seis- of this building. mic intensity and directional peak acceler- Long-period Seismic Motion ation for the main strong motion stations. Long-lasting Shaking In terms of observed values, observa- Based on the size of the 2011 earth- tion stations such as Sendai Government As mentioned earlier the epicentral area quake, strong long-period seismic mo-

24 The Japan Journal DECEMBER 2011 The Japan Journal DECEMBER 2011 25 seismic intensity scale Figure 8: Location of surveyed cities and towns was recorded. As a Tono City result, BRI confirmed Miyako City

significant damage in Kitakami City Yamada Town areas such as the cities Otsuchi Town of Osaki in Miyagi Hiraizumi Town Kamaishi City Ofunato City Prefecture and Kurihara City Rikuzentakata City

Sukagawa in Kesennuma City Fukushima Prefecture, Minamisanriku Town the town of Nasu in Ishinomaki City Onagawa Town Nasu-gun, Tochigi Higashi Matsushima City Photo 1: Mid-story collapse in a low-rise Prefecture and the Matsushima Town Shiogama City building cities of Hitachiota Shichigahama Town Tagajo City and Naka in Ibaraki Sendai City Natori City tion was predicted, but in fact, this was Prefecture. On the Iwanuma City Watari Town not seen to a great extent in the Tokyo other hand, in Yamamoto Town metropolitan area. In the Osaka Bay Kurihara, Miyagi Shiroishi City Nasu Town Fukushima City Nihonmatsu City area, however, despite being about Prefecture, which re- Yaita City Miharu Town Koriyama City 770 km from the epicenter, high-rise corded level 7 on the Shirosato Town Sukagawa City buildings resonated at an approximate seismic intensity Kasama City Shirakawa City Hitachiota City City 7-second cycle due to the long-period scale, the damage was Hitachi City Shimotsuma City Naka City shaking, and in one case a sway of 260 not so great compared Hitachinaka City centimeters was recorded near the top of with the instrumental Furukawa City Mito City Bando City Oarai Town City a building on the fifty-second floor. seismic intensity that Joso City Hokota City Note that even in the Tokyo metropoli- was recorded. City Kashima City Itako City Ryugasaki City tan region, more than a little elevator The types of City Sakae Town Inashiki City Surveyed cities and towns and non-structural damage in high-rise damage observed Urayasu City buildings has been reported. due to seismic move- ment of the 2011 earthquake can be motion, this includes roofing tile dam- Damage to Buildings and Homes broadly categorized as either “damage age such as falling bricks or tiles, dam- Due to Seismic Motion attributable to shaking due to seismic age to interior materials and exterior motion” and “damage attributable to walls (Photo 2), tilted buildings and While the 2011 earthquake was of a ground deformation.” story collapses (Photo 3). These forms scale that Japan has never before experi- As forms of damage due to seismic of damage are largely consistent with enced, buildings designed according to the damage seen in past earthquakes. the new earthquake resistance standards As for damage due to ground defor- (earthquake resistance standards intro- mation, multiple cases of damage to duced since June 1981) are believed to foundations and wall surfaces associated have suffered little structural damage. with the breaking up of the ground or re- On the other hand, some problems have taining walls and the tilting or collapse of become clear. Among them the falling buildings were observed. In addition, of non-structural materials such as ceil- since we observed many cases of signifi- ings was seen even in buildings de- cant damage on residential land built signed according to the new earthquake upon lowland swamp or filled-in rice resistance standards, and many buildings paddies, we believe it is possible that the suffered damage in the form of tilting Photo 2: Fallen parts of exterior walls soft ground amplified the seismic motion. due to widespread ground liquefaction. Investigating the causes and finding so- Damage to Buildings of Steel Frame lutions to these types of damage will be Construction a major challenge in the future. BRI conducted an exterior survey of Damage to Wooden Buildings damage to general buildings of steel frame construction such as office build- BRI conducted a survey of damage to ings in Miyagi, Fukushima and Ibaraki wooden buildings in Miyagi, Fukushima, Prefectures. In addition, BRI conducted Tochigi and Ibaraki prefectures, includ- damage surveys of structures such as ing in the city of Kurihara, Miyagi school gymnasiums designed according Prefecture, where intensity level 7 on the Photo 3: First-floor story collapse to the old earthquake resistance standards

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which suffered damage were buildings Buckling designed according to the old earthquake resistance standards. On the other hand, very few buildings designed according to Fracture the current earthquake resistance stan- dards suffered damage, although in some SRC buildings, damage such as buckling in the main reinforcements near base plates at the bottom of columns, shear cracks at the beam-column joints or hori- zontal cracks at the concrete placing Photo 4: Damage to exposed column Photo 5: Buckling of bracing materials joints were seen. At housing complexes bases and joint fracture in particular, we also observed many cases where shear failure occurred with across a widespread area in Ibaraki ture of roof horizontal bracing; (v) crack- non-structural walls around entrances and Prefecture where intensity 5-upper to ing of column base concrete; and (vi) veranda-side mullion walls (Photo 9), 6-upper shocks were observed. other damage (overturning of floor strut, and this occurred irrespective of whether In the exterior survey damage to etc.). However, the proportion of struc- old or current earthquake resistance stan- general buildings of steel frame con- tures that suffered significant structural dards had been adopted. struction, we observed several cases of damage such as fractured vertical bracing In the 2011 earthquake, despite the damage to the bracing structures of or joint fractures can be considered low fact that there was relatively less major buildings such as parking lots, such as compared with the results*1 of a similar structural damage, we did see cases buckling of the bracing materials or survey conducted at the time of the 2004 where public buildings such as city halls damage to the bracing joints. Damage to Mid-Niigata Prefecture Earthquake. constructed according to the old earth- the exposed column bases of parking quake resistance standards had suffered lots was also observed (Photo 4). In the Damage to Reinforced Concrete damage to the extent that they could not scope of this survey, no cases of critical Buildings, etc. damage such as fracture of major struc- tural components like columns and We conducted a damage survey of beams were observed. reinforced concrete (RC) buildings In the damage survey of school gym- and steel reinforced concrete (SRC) nasiums, etc. in Ibaraki Prefecture, we buildings, mainly in the urban areas observed (i) buckling and fracture of ver- of regions where stations recorded tical braces and fracture of joints (Photo seismic intensities of 6-lower and 5); (ii) buckling in the diagonal bracing over in Iwate, Miyagi, Fukushima and of lattice columns (Photo 6); (iii) damage Ibaraki Prefectures. to the joints between reinforced concrete Considering the large seismic in- columns and the roof (bearing support tensities observed in each area, we gen- parts); (iv) curvature, buckling and frac- erally found that structural damage was Photo 7: Floor collapse on the first floor not so heavy. However, in areas such of a piloti structure as Wakabayashi Ward in Sendai and the city of Sukagawa on land that was once rice paddies and moats, a relative- ly higher concentration of structural damage was seen. Based on this, we believe it is possible that ground condi- tions had something to do with the damage that occurred. Most of the structural damage seen in this survey was largely consistent with earthquake damage observed in the past. For instance, major damage such as mid- floor collapses in low-rise buildings Buckling (Photo 1), first-floor collapses (Photo 7) of soft first-story piloti structures and Photo 6: Buckling of diagonal bracing column shear failure due to loss of verti- of lattice columns (part shown with cal load carrying capacity (Photo 8) also yellow dotted line) occurred, but most of the structures Photo 8: Shear failure

26 The Japan Journal DECEMBER 2011 The Japan Journal DECEMBER 2011 27 structural damage such as story collapse, damage to exterior walls, curtain wall structures, openings and other non- structural materials was observed. We observed extensive damage as- sociated with exterior walls and curtain wall structures, including the shedding of exterior tiles from RC walls and the dropping of things like outer wall panels (Photo 12). We observed many buildings in which the glass from glass openings Photo 12: Fallen exterior wall panels had broken. In gymnasiums, interior materials had been damaged or had fall- en from the interior walls of the arena, Photo 9: Non-structural shear failure and from the interior materials above the stage. The ceilings of gymnasiums built be used. These buildings are supposed using a variety of construction tech- to function as bases of operation during niques were also damaged, with the se- an emergency, and the loss of those verity of damage ranging from small- functions may serve to again highlight scale damage along the edges to large- the need for earthquake retrofitting. scale damage where entire ceilings fell down. At an airport terminal building Damage to Residential Land and where the lobby ceiling had fallen down Photo 13: Fallen ceiling at an airport Ground (Photo 13), we observed that the layout departure lobby (yellow dotted line of the roof and ground below was un- indicates where the ceiling droppage In the 2011 earthquake, building dam- even and complicated. occurred) age due to ground liquefaction occurred As for damage to non-structural mainly in the bay area of the Kanto re- components, those built with relatively higher suffered relatively more damage gion. In our survey, we observed the old construction methods suffered the and falling. widespread occurrence of damage such most damage, and we also observed as sand boiling and ground deformation that non-structural components placed Concluding Remarks associated with liquefaction in the allu- vial plain area along the Tone river on Considering the size of the earthquake the border between Ibaraki and Chiba and the instrumental seismic intensity Prefectures and in the city of Urayasu, recorded at various locations, the Chiba Prefecture. Buildings with severe damage to building structures due to tilting (Photo 10) were also seen, but seismic movement was relatively little. within the scope of our survey, we did However, the degree of damage to not observe cracked or damaged founda- buildings designed according to the old tions from the exterior. earthquake resistance standards was In Miyagi, Fukushima and Tochigi greater. Looking ahead, it will be neces- Prefectures, significant damage (Photo sary to review technical standards, in- 11) associated with sliding of the soil oc- cluding measures to deal with ceiling curred mainly in developed housing collapses and ground liquefaction, areas (at their periphery in particular). In Photo 10: Tilting due to liquefaction which became significant problems in some areas we saw that deformation the 2011 earthquake. occurred again on developed land that Finally, we would like to express had been damaged by past earthquakes. our deepest condolences to those who There was also a case on residential land lost their lives in the tsunami and earth- which suffered significant damage quake and to their families, and offer where the soil under the foundations had our heartfelt sympathies to everyone slid away, but where the foundations affected by the disaster. were still holding together. Note: *1 NILIM/BRI: Report on the Damage to Nonstructural Damage Investigation of Buildings Components Due to the Mid Niigata Prefecture Photo 11: Damage due to a landslide Earthquake in 2004, pp.305–353, Photo 8: Shear failure In buildings which did not suffer major from a sloped edge October, 2006 (in Japanese)

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