ISSN 1346-7328
Technical Note of NILIM No.647
ISSN 0453-4972
BRI Research Paper No.150

Technical Note of National Institute for Land and Infrastructure Management
No. 647

September 2011

BRI Research Paper
No. 150

September 2011

Summary of the Field Survey and Research on“The 2011 off the Pacific coast of Tohoku Earthquake”(the Great East Japan Earthquake)

National Institute for Land and Infrastructure Management (NILIM)
Ministry of Land, Infrastructure, Transport and Tourism, Japan
Building Research Institute (BRI)
Incorporated Administrative Agency, Japan

Copyright©2011 by NILIM and BRI
No part of this book may be reproduced by any means, or transmitted, ortranslated into a machine language without the written permission of the
publisher or the authors.

Preface
A magnitude 9.0 earthquake occurred off the coast of Sanriku, Japan at
14:46 JST on Friday, March 11, 2011 and triggered extremely destructive
tsunami waves. The earthquake and tsunami destroyed, damaged, or washedaway a number of buildings, houses and structures in Northeast Japan,
including Iwate, Miyagi, Fukushima, Ibaraki, and Chiba prefectures. The
highest Japanese seismic intensity scale of 7 was recorded at Kurihara city inthe northern part of Miyagi prefecture. The earthquake was named the 2011 off
the Pacific coast of Tohoku Earthquake (the Great East Japan Earthquake) by
the Japanese government.
In order to learn lessons from the unprecedented disaster and contribute to
the improvement of disaster mitigation measures, the National Institute forLand and Infrastructure Management (NILIM) and the Building ResearchInstitute (BRI) has sent staff members to the affected regions and conducted
extensive surveys on the damage to buildings and residential lands caused by
the earthquake, tsunami and subsequent fires. The types and parts of buildingson which these surveys have been conducted include wood houses, reinforced
concrete buildings, steel buildings, residential lands, non-structuralcomponents and seismically isolated buildings. In addition, NILIM and BRI
have conducted scientific researches on the earthquake and tsunami andanalyzed the recorded earthquake motions on various sites across Japan.
This report consists of the main results from these surveys and researches.
We hope that this report will be informative in developing effective measures tomitigate damage from future earthquakes and tsunamis in Japan and otherearthquake-prone countries in the world.
Finally, we would like to express our deepest condolences to those wholost their families and those who are suffering from the disaster. In addition, we
would like to express our heartfelt appreciation to people from around theworld for their warm support and cordial friendship.
September, 2011
Juntaro Tsuru
Deputy Director-General
The National Institute for Land and Infrastructure Management
Shuzo Murakami
Chief Executive
The Building Research InstituteTable of Contents

Preface ________________________________________________________(1)＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿ 1

1.

Introduction

2.

Outline of Research and Field Survey ＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿ 3＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿ 3

2.1

Outline of Research

2.2

Outline of Field Survey＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿4

Overview of Damage＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿ 73.

＿＿＿＿＿＿＿＿＿＿＿ ＿＿＿ 7

3.1

Distribution of JMA Seismic Intensity

3.2

Casualties and Damage to Buildings and Utilities ＿＿＿＿＿＿＿＿＿＿ 9

3.3

Regions Affected by Tsunami

3.4

Inspections of Damaged Buildings and Residential Lands ＿＿＿＿＿＿＿ 13

3.5

Temporary Housing＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿ 14

3.6

Building Restrictions＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿ 15

4.

＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿ 11＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿

17＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿

17

Outline of Earthquake and Tsunami
4.1

Earthquake Mechanism

4.2

Relocation of Earthquakes

4.3
4.4
5

＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿ 18

High Frequency Energy Radiation Duration of and
its Corresponding Magnitude
Tsunami＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿ 19＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿

20

Earthquake Motions and Strong Motion Observation in Buildings _____＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿ 27

5.1

Distribution of Seismic Intensities

5.2

Characteristics of Earthquake Motions ＿＿＿＿＿＿＿＿＿＿＿＿＿＿

5.3

Results of BRI Strong Motion Observation Network

6

27

27

＿＿＿＿＿＿＿＿＿ 29

Damage to Buildings by Earthquake Motions ＿＿＿＿＿＿＿＿＿＿＿＿

41＿＿＿＿＿＿＿＿

41

6.1

Policy on Earthquake Damage Investigation for Buildings

6.2

Damage to Wood Houses _________________________________

43

6.3

Damage to Reinforced Concrete Buildings ____________________

69

6.4

Damage to Steel Gymnasiums

6.5

Damage to Residential Land

6.6

Damage to Nonstructural Components ______________________________109

7______________________________ _____ 89__________________________________

Damage to Buildings in Inundation Areas Induced by Tsunami

101__________119

7.1

Introduction_________________________________________________ 119

7.2

Classification and Discussion of Damage Patterns ____________________ 119

7.3

Database for Investigated Buildings ________________________________ 126

7.4

Damage to Wood Buildings ______________________________________127

7.5

Conclusion ___________________________________________________ 140

8

Damage of Buildings, etc due to Fire ___________________

141

8.1

Objective of Survey ____________________________________________141

8.2

Damage by Fire due to Tsunami ___________________________________ 143

8.3

Damage by Fire due to Earthquake Motions _________________________ 146
Response of Seismically Isolated Buildings ____________________________149

99.1

Outline of Surveyed Buildings ____________________________________149

9.2

Behavior of Seismically Isolated Buildings ___________________________ 151

9.3

Results of Survey _______________________________________________161

10Concluding Remarks ___________________________________________ 163

List of authors
Chapter 1 : Isao Nishiyama (NILIM), Shoichi Ando (BRI)
Chapter 2 : Takashi Nagasaki (BRI), Norimitsu Ishii (BRI)
Chapter 3 : Ryou Ootake (NILIM), Yoshiyuki Shibata (NILIM), Masashi Mori (NILIM),
Satoshi Arikawa (NILIM), Shuuichi Takeya (NILIM),
Atsuhito Ooshima (NILIM), Tomohiko Sakata (NILIM), Norimitsu Ishii (BRI)
Chapter 4 : Nobuo Hurukawa (BRI), Tatsuhiko Hara (BRI), Yushiro Fujii (BRI)
Chapter 5 : Toshihide Kashima (BRI), Shin Koyama (BRI), Izuru Okawa (BRI)
Chapter 6 : Isao Nishiyama (NILIM), Takahiro Tsuchimoto (NILIM),
Takafumi Nakagawa (BRI), Yasuhiro Araki (BRI), Chihiro Tsuda (BRI),
Hiroto Kato (BRI), Hiroshi Fukuyama (BRI), Takashi Hasegawa (BRI),
Koichi Morita (BRI), Tadashi Ishihara (NILIM), Yoshihiro Iwata (NILIM),
Tsutomu Hirade (BRI), Namihiko Inoue (NILIM), Hiroshi Arai (NILIM),
Yoshio Wakiyama (BRI)
Chapter 7 : Yasuo Okuda (BRI), Takahiro Tsuchimoto (NILIM)
Chapter 8 : Koji Kagiya(NILIM), Ichiro Hagiwara (BRI), Tatsuya Iwami (NILIM),
Yoshihiko Hayashi, Junichi Suzuki (BRI), Hideki Yoshioka (NILIM)
Chapter 9 : Masanori Iiba (BRI), Taiki Saito (BRI), Namihiko Inoue (NILIM)
Chapter 10 : Isao Nishiyama (NILIM), Shoichi Ando (BRI), Tadashi Tonami (NILIM),
Atsuo Fukai (NILIM), Masanori Iiba (BRI)
Editors Izuru Okawa (BRI), Takashi Hasegawa (BRI), Koichi Morita (BRI),
Hitomitsu Kikitsu (NILIM), Yoshihiro Iwata (NILIM)1. Introduction
An earthquake of moment magnitude (Mw) 9.0 occurred off Sanriku coast at 14:46
JST on March 11, 2011 and caused tremendous damage of collapse and washed-away ofbuildings, houses and other structures by ground motion and tsunami in the Pacificcoast of eastern Japan, including prefectures of Iwate, Miyagi, Fukushima, Ibaraki and
Chiba. The earthquake has recorded the seismic intensity 7, highest in the Japan
Meteorological Agency (hereinafter referred to as JMA) scale, in north of Miyagi
prefecture (Kurihara city). The JMA named the earthquake as “The 2011 off the Pacificcoast of Tohoku Earthquake” (hereinafter referred to as ‘the 2011 Tohoku earthquake’)
and the national government named the disaster “the Great East Japan Earthquake”
based on a Cabinet decision. As of July 11, the JMA has confirmed six major
aftershocks of magnitude 7 or larger. The Japanese National Police Agency has
confirmed 15,550 deaths, 5,688 injuries and 5,344 people missing, as well as 224,798
housing units collapsed, 434,327 housing units partially damaged and 32,443
non-residential buildings damaged.
The seismic intensity 6 lower (6-) in JMA scale has been recorded for the first timein Tsukuba city, Ibaraki prefecture, where the National Institute for Land andInfrastructure Management (hereinafter referred to as NILIM) and the Building
Research Institute (hereinafter referred to as BRI) are located. Both research institutes
share the main building. Some office rooms suffered from falling of cabinets andbookshelves, even a staff has been locked indoors. Although cracks of wall and otherstructural damage occurred in the main building, fortunately there was no one injured.
Immediately after confirmation of safety of staff members who were working in thebuildings both institutes initiated to collect information on earthquake damage. Some
members who had visited Tokyo and so forth could not come to office for the next few
days, since all the transportation systems stopped. As the e-mail system even within theinstitute has been unstable, it was difficult to collect broader information, except using
the micro-wave communication lines that are owned by the Headquarter of the Ministryof Land, Infrastructure, Transport and Tourism (hereinafter referred to as MLIT) in
Kasumigaseki, Tokyo. Some NILIM staff members remained at office in order to keep
contacts with MLIT and to collect further information, while other staffs returned theirhomes to continue to collect information and to prepare for the next days before sunset
because electricity supply has stopped within both institutes and even traffic signals
were out of order.
From the next day, Saturday March 12, both NILIM and BRI started activities
including field survey and established the “NILIM / BRI Joint Survey Team on Building
Damage Investigation (hereinafter referred to as Joint Survey Team; Note 1)” in order to-1-

prepare for the requests of support from the earthquake affected areas and for the future
measures against earthquake and tsunami through grasping damage situations tobuildings. The Joint Survey Team has supported surveys on earthquake and the damageof buildings caused by the earthquake motions, mainly responding to the requests of
MLIT for the first two weeks after the earthquake. In succession, NILIM and BRI
jointly dispatched the team to the affected areas in Tohoku and Kanto regions in order to
get an overall picture on damage by ground motion and also carried out surveys on
damage of buildings in tsunami affected areas and so on, as joint surveys.
This report summarizes the research and studies that were mainly carried out
during the six weeks after the earthquake until April 20 and that were published inJapanese as “Quick report of the Field Survey and Research on the 2011 off the Pacificcoast of Tohoku earthquake (The Great East Japan Earthquake)”. However the researchand studies conducted after the date are also partly included. The Joint Survey Team has
held a lot of meetings and continues discussion on survey results and necessary
additional surveys. This report does not cover all the disaster since the earthquake
affected area was huge spreading from Tohoku region to Kanto region, as thename, ”the Great East Japan Earthquake” indicates.
Note 1: Members of the NILIM/BRI Joint Survey Team, as of April 20.
from NILIM, Kenji Takai, Tadashi Tonami, Isao Nishiyama, Atsuo Fukai, Tomoko Takagi, Ichiro
Minato, Yoshiyuki Shibata, Katsuhiko Kusuda, Masanori Nishiyama, Haruhiko Watanabe, Hiroyuki
Tanano, Yuji Kobayashi, Hiroshi Arai, Namihiko Inoue, Akiyoshi Mukai, Tatsuya Azuhata,
Hitomitsu Kikitsu, Takahiro Tsuchimoto, Yoshihiro Iwata, Haruhiko Suwada, Tomohiro Naruse, Koji
Kagiya, Tatsuya Iwami, Hideki Yoshioka, Ryo Ootake, Satoru Takahashi, Masashi Mori, Hiroshi
Hasegawa, Kazuo Nishida, Satoshi Arikawa, Shuichi Takeya, Nozomi Kiuchi, Tomohiko Sakata, 33
staff members,from BRI, Hiroshi Ito, Juntaro Tsuru, Takashi Nagasaki, Harunobu Murakami, Akira Iwasaki,
Ryosuke Sasa, Shigeto Kawasaki, Masaaki Hasegawa, Shigenori Ootaka, Shuichi Go, Kazuhiko
Karasawa, Hiroyuki Tasaki, Kunihiko Miyazawa, Zenichi Naito, Shoichi Ando, Takao Sawachi,
Naoji Hasegawa, Nobuo Hurukawa, Izuru Okawa, Toshihide Kashima, Shin Koyama, Toshiaki
Yokoi, Bunichiro Shibazaki, Tatsuhiko Hara, Tadashi Ishihara, Tsutomu Hirade, Masanori Iiba,
Hiroshi Fukuyama, Hiroto Kato, Takashi Hasegawa, Yasuhiro Araki, Toshikazu Kabeyasawa, Mizuo
Inukai, Koichi Morita, Masanori Tani, Nobuyoshi Yamaguchi, Shiro Nakajima, Takafumi Nakagawa,Yoshio Wakiyama, Taiki Saito, Tomohisa Mukai, Yasuo Okuda, Yuushiro Fujii, Ichiro Hagiwara,
Yoshihiko Hayashi, Junichi Suzuki, Norimitsu Ishi, Wataru Gojo, 48 staff members
Note 2: Source of information (web-sites)
The web-sites for the 2011 Tohoku earthquake are established in NILIM(http://www.nilim.go.jp) and BRI (http://www.kenken.go.jp, http://www.iisee.kenken.go.jp) showing
original information of individual researches and surveys that are bases of this report.
Some data that are updated before the publication of this report were also added, when it isavailable.

-2-

2.

Outline of Research and Field Survey

After the 2011 Tohoku earthquake, the Joint Survey Team started a series ofresearch and field survey, and some of them were done in cooperation with otherinstitutes. The outline of the research and field survey from March 11th to April 20th isas follows.
2.1

Outline of Research

The Joint Survey Team grasped the features of the 2011 Tohoku earthquake andtsunami based on observational data from research institutes in Japan and overseas
including the Japan Meteorological Agency (JMA) and the National Research Institutefor Earth Science and Disaster Prevention (NIED), strong motion seismogram of the
BRI Strong Motion Observation Network, etc.
2.1.1 Mechanism of earthquake and tsunami
BRI confirmed the mechanism of the 2011 Tohoku earthquake through obtaining
its precise hypocenters, identifying fault planes of major earthquakes and estimating
magnitude based on duration of high frequency energy radiation. BRI also estimated thesource of the tsunami using the tsunami waveform inversion based on data fromtsunami sensors and tide gauges around Japan and simulated the tsunami based on thetsunami source model. Researchers involved are as follows.

BRI

2.1.2

Table 2.1-1 List of Researchers (1)Nobuo Hurukawa, Dr.
Research Coordinator
Tatsuhiko Hara, Dr.
Chief Research Scientist
Yushiro Fujii, Dr.
Senior Research Scientist

Earthquake motion observation

NILIM and BRI showed the feature of the earthquake motion of the mainshock
and its major aftershocks based on strong motion seismograms of the BRI Strong
Motion Network, etc. Researchers involved are as follows.

NILIM
BRI

Table2.1-2 List of Researchers (2)Tatsuya Azuhata, Dr.
Division HeadShin Koyama, Dr.
Chief Research Engineer
Toshihide Kashima, Dr.
Senior Research Engineer
Tadashi Ishihara, Dr.
Senior Research Engineer

-3-

2.2

Outline of Field Survey

NILIM and BRI sent a total of 150 researchers to disaster areas in Iwate, Miyagi,
Fukushima, Ibaraki, Tochigi and Chiba prefectures (Surveyed cities and towns areshown in Fig.2.2-1) from March 12th, the day after the 2011 Tohoku earthquake, toApril 16th, 2011 and surveyed damage situation on buildings categorized according tobuilding structure, building use, cause of damage (earthquake motion, tsunami, fire), etc.
Some surveys were done on the request of MLIT. Researchers involved in those fieldsurveys are as follows.

NILIM

BRI

Table 2.2-1 List of Researchers (3)Ichiro Minato
Senior Research Fellow
Tatsuya Azuhata, Dr.
Division Head
Atsuo Fukai
Division Head
Takahiro Tsuchimoto, Dr.
Division Head
Masashi Miyamura
Senior Researcher
Namihiko Inoue
Senior Researcher
Hiroshi Arai, Dr.
Senior Researcher
Hitomitsu Kikitsu, Dr.
Senior Researcher
Yoshihiro Iwata, Dr.
Senior Researcher
Haruhiko Suwada, Dr.
Researcher
Masanori Iiba, Dr.
Director
Chief Research Engineer
Naohito Kawai, Dr.
(at present, Professor of
Kogakuin University)
Ichiro Hagiwara, Dr.
Chief Research Engineer
Yasuo Okuda, Dr.
Chief Research Engineer
Hiroshi Fukuyama, Dr.
Chief Research Engineer
Taiki Saito, Dr.
Chief Research Engineer
Shiro Nakajima, Dr.
Chief Research Engineer
Koichi Morita, Dr.
Chief Research Engineer
Nobuyoshi Yamaguchi, Dr.
Senior Research Engineer
Hiroto Kato
Senior Research Engineer
Tsutomu Hirade, Dr.
Senior Research Engineer
Takashi Hasegawa, Dr.
Senior Research Engineer
Yoshio Wakiyama, Dr.
Senior Research Engineer
Takafumi Nakagawa, Dr.
Senior Research Engineer
Tadashi Ishihara, Dr.
Senior Research Engineer
Yasuhiro Araki, Dr.
Research Engineer
Masanori Tani, Dr.
Research Engineer
Toshikazu Kabeyasawa, Dr.
Research Engineer
Hideki Matsumoto
Cooperative Researcher-4-

Tono City

Miyako City

Iwate Pref.

Yamada Town

Kitakami City

Otsuchi Town
Kamaishi City

Hiraizumi Town

Ohunato City
Kurihara City

Rikuzentakata City
Kesennuma City
Minamisanriku Town

Miyagi Pref.

Ishinomaki City
Onagawa Town
Higashimatsushima City
Matsushima Town
Shiogama City
Shichigahama Town
Tagajo City
Sendai City

Natori City
Iwanuma City
Watari Town
Yamamoto Town
Shiroishi Town
Fukushima City
Nihonmatsu City

Fukushima Pref.
Nasu Town
Yaita City

Miharu Town
Koriyama City
Sukagawa City
Shirakawa City
Hitachiota City
Hitachi City
Naka City
Hitachinaka City
Mito City
Oarai Town
Omitama City
Hokota City
Kashima City
Itako City
Kamisu City
Inashiki City

Shirosato Town
Kasama City
Chikusei CityTochigi Pref.
Shimotsuma City

Koga City
Bando City
Joso City

Ibaraki Pref.

Tsuchiura City
Ryugasaki City
Sakae Town

Chiba Pref.

Urayasu City

ゆFig.2.2-1 Location of Surveyed Cities and Towns-5-

Surveyed Cities and
Towns

-6-

3. Overview of Damage
The 2011 Tohoku earthquake was followed by tsunami and several aftershocks withlargest seismic intensities greater than 5 in JMA scale and caused extensive damage inbroad areas including the Pacific coast of Tohoku and Kanto region. With a sequence ofaftershocks including the Off Miyagi Pref. Earthquake of April 7, the Earthquake in
Hamadori, Fukushima Pref. of April 11 and 12, and the earthquake in northeastern part ofChiba prefecture of May 22, a large number of casualties and damage to buildings werereported in more than 20 prefectures. This chapter mainly presents the overview of damage
to buildings based on the press releases by national agencies. Note that the data presented
here is based on press releases on July 11 and earlier, and subject to change.
3.1 Distribution of JMA Seismic Intensity
Table3.1-1 summarizes municipalities where JMA seismic intensities 6 and 7 wererecorded in the 2011 Tohoku earthquake. Fig. 3.1-1 illustrates distribution of JMA seismic
intensity in the seismic affected prefectures.

JMA Seismic
Intensity
7

6 Upper

6 LowerTable 3.1-1 Largest JMA Seismic Intensity of municipalities
in the 2011 Tohoku earthquake 3-1)
Prefecture

Municipalities

Miyagi

Kurihara city
Sendai city Miyagino ward, Ishinomaki city, Shiogama city, Natori city, Tome city,
Higashimatsushima city, Osaki city, Zao town, Kawasaki town, Yamamoto town, Ohira village,
MiyagiWakuya town, Misato town
city, Sukagawa city, Kunimi town, Kagamiishi town, Tenei village, Naraha town,
Fukushima Shirakawa
Tomioka town, Okuma town, Futaba town, Namie town, Shinchi town
Hitachi city, Takahagi city, Kasama city, Hitachiomiya city, Naka city, Chikusei city, Hokota city,
IbarakiOmitama city
Tochigi
Utsunomiya city, Moka city, Ohtawara city, Ichikai town, Takanezawa town
Ofunato city, Hanamaki city, Ichinoseki city, Kamaishi city, Oshu city, Takizawa village, Yahaba
Iwate
town, Fujisawa town
Sendai city Aoba ward, Sendai city Wakabayashi ward, Sendai city Izumi ward, Kesennuma city,
MiyagiShiroishi city, Kakuda city, Iwanuma city, Ogawara town, Watari town, Matsushima town, Rifu
town, Taiwa town, Osato town, Tomiya town, Minamisanriku town
Fukushima city, Koriyama city, Iwaki city, Soma city, Nihonmatsu city, Tamura city, Minamisoma
city, Date city, Motomiya city, Kori town, Kawamata town, Inawashiro town, Nishigo village,
Fukushima Nakajima village, Yabuki town, Tanagura town, Tamakawa village, Asakawa town, Ono town,
Hirono town, Kawauchi village, Iitate village
Mito city, Tsuchiura city, Ishioka city, Joso city, Hitachiota city, Kitaibaraki city, Toride city,
Tsukuba city, Hitachinaka city, Kashima city, Itako city, Bando city, Inashiki city, Kasumigaura
Ibarakicity, Sakuragawa city, Namegata city, Tsukubamirai city, Ibaraki town, Shirosato town, Tokai
village, Miho village
Tochigi
Nasushiobara city, Nasukarasuyama city, Haga town, Nasu town, Nakagawa town
Gunma

Kiryu city

SaitamaMiyashiro town

Chiba

Narita city, Inzai city-7-Fig. 3.1-1 Distribution of JMA seismic intensity in the 2011 Tohoku earthquake3-1)-8-3.2 Casualties and Damage to Buildings and Utilities
3.2.1 Casualties
Table 3.2-1 shows the numbers of deaths, injuries and people missing due to a seriesof earthquakes as of July 11, 20113-2). It also shows the number of evacuees in shelters,
hotels, and houses of their relatives and friends. The number of evacuees has significantly
decreased since mid-March when it exceeded 450,000. However, it still amounted to
68,816 as of June 303-3).
Table 3.2-1 Casualties and Evacuees3-2)~3)
Prefecture
Hokkaido
Aomori
Iwate
Miyagi
Akita
Yamagata
Fukushima
IbarakiTochigi
Gunma
Saitama
Chiba
Tokyo
Kanagawa
Niigata
Yamanashi
NaganoShizuoka
Others
Total

Casualties*1
Missing[person]

Deaths[person]
1
3
4,584
9,300

Evacuees*1*2
Injuries[person]

1
2,247
2,807

2
1,600
24
4
1

286
1

20
7
4

2

15,550

5,344

3
61
186
3,777
12
29
236
694
131
38
42
248
90
129
3
2
1
4
2
5,688

[person]
959
848
9,339
15,871
1,240
2,300
19,484
844
1,404
1,073
1,075
3,432
2,216
83
3,967
289
349
684
3,359
68,816

Notes: *1 Casualties and Evacuees include those caused by the Off Miyagi Pref. Earthquake of April 7,
the Earthquake in Hamadori, Fukushima Pref. of April 11 and 12, and the Earthquake innortheastern part of Chiba Pref. of May 22.
Notes: *2 Evacuees also include those who relocated due to the 2011 Accident at Fukushima Nuclear
Power Stations.

-9-3.2.2 Damage to buildings
Table 3.2-2 shows the number of residential and non-residential buildings damaged by
the disaster3-2) and the number of earthquake-related fires3-4).
Table 3.2-2 Number of Buildings Damaged3-2) and 3-4)
Residential Buildings
Prefecture

Hokkaido
Aomori
Iwate
Miyagi
Akita
Yamagata
Fukushima
IbarakiTochigi
Gunma
Saitama
Chiba
Tokyo
Kanagawa
Others
Total

Total
Collapse*1*2[housing
unit]

Half
Collapse*1[housing
unit]

307
21,004
66,929854
3,313
54,00637
16,198
2,265
257

80
32,45815,890
2,079
6
5
8,310
11
7

782

107,779

Total burndown*1[housing
unit]

Partial burndown*1[housing
unit]

15
114
77

3
37

1

1
12

3

117,019

263

Partially
Damaged*1[housing
unit]
5
96
2,668
87,607
3

Non-Residential
Buildings
Damaged*1

NumberofFires*1[building][case]

470
1,193
1,538
17,9003

100,881
138,497
57,627
16,1501,800
28,440257279
17434,327

1,015
9,056
295
195
33
708
20
1
16
32,443

5
26
163
1
11
37
2
13
13
33
6
1
311

Notes: *1 Damage and fires include those caused by the Off Miyagi Pref. Earthquake of April 7, 2011, theEarthquake in Hamadori, Fukushima Pref. of April 11 and 12, and the Earthquake in northeastern part ofChiba Pref. of May 22. Due to the inability to collect information in some areas affected by the tsunami
and the 2011 Accident at Fukushima Nuclear Power Stations, the numbers presented in this table may
not show the full extent of the damage.
*2 Total Collapse includes housing units washed away by the tsunami.

3.2.3 Damage to utilities
Table 3.2-3 shows the maximum damage to electricity supply, city gas supply, watersupply and communication.
Table 3.2-3 Maximum Damage to Utilities
Number of
Damaged Units

Date

Electricity supply (Power
Failure)City gas supply (Suspension)

8,450,000
458,495

March 23*1

Water supply (Suspension)

1,700,000

March 15

Communication (Fixed phone
Suspension)

879,500

March 12

March 11

SourcePress release by Tohoku Electric Power
Company and Tokyo Electric Power Company
Press release by the Japan Gas Association
Press release by Ministry of Health, Labour andWelfarePress release by Nippon Telegraph andTelephone (NTT) East Corporation

Note: *1 The number of damaged units of Gas supply (Suspension) as of March 23 reflects some correction later on.

-10-

3.3 Regions Affected by Tsunami
3.3.1 Tsunami affected area
The Geospatial Information Authority of Japan (GSI) estimated tsunami affected area
and the total area in 6 prefectures (Aomori, Iwate, Miyagi, Fukushima, Ibaraki, and Chiba)
is about 561km2. Table3.3-1 shows tsunami affected area classified by municipalities3-5).
Table 3.3-1 Tsunami affected area(classified by municipalities)3-5)
Prefecture/
Municipality

Tsunamiaffectedarea(km2)*1
24
9
6
5
3
0.5
58
10
8
4
13
7
4
5
1
1
1
2
1
327
20

Municipality
area
(km2)
844
305
120
253
72
94
4,946
1,260
323
623
232
441
201
263
993
156
70
81
303
2,003
58

Prefecture/
Municipality

Tsunamiaffectedarea(km2)*1
112
15
29
39
2
3
1
2
3
6
11
23
1
4
1
3
3
3
3
2
2

Municipality
area
(km2)
2,456
1,231
198
399
58
103
68
79
51
223
46
1,444
217
226
194
187
99
106
147
208
23

Aomori Prefecture
Fukushima Prefecture
Hachinohe city
Iwaki city
Misawa city
Soma city
Rokkasho village
Minamisoma city
Oirase town
Hirono town
Hashikami town
Naraha town
Iwate Prefecture
Tomioka town
Miyako city
Okuma town
Ofunato city
Futaba town
Kuji city
Namie town
Rikuzentakata city
Shinchi town
Kamaishi city
Ibaraki Prefecture
Otsuchi town
Mito city
Yamada town
Hitachi city
Iwaizumi town
Takahagi city
Tanohata village
Kitaibaraki city
Fudai village
Hitachinaka city
Noda village
Kashima city
Hirono town
Kamisu city
Miyagi Prefecture
Hokota city
Oarai town
Sendai city;
Miyagino ward
Sendai city;
29
48
Tokai village
337
Wakabayashi ward
Sendai city;
3228
Chiba Prefecture
17
689
Taihaku ward
Ishinomaki city
73
556
Choshi city
184
Shiogama city
618
Asahi city3
130
Kesennuma city
18333
Sosa city
1102
Natori city
27
100
Sammu city
6146
Tagajo city
620
Oamishirasato town
0.5
58
Iwanuma city
29
61
Kujukuri town
2
24
Higashimatsushima city
37
102
Yokoshibahikari town
1
67
Watari town
35
73
Ichinomiya town
1
23
Yamamoto town
24
64
Chosei village
128
Matsushima town
2
54
Shirako town
1
27
Shichigahama town
5
13
Rifu town
0.5
45
Total
561
12,382
Onagawa town
3
66
Minamisanriku town
10164
Note: *1 When the tsunami affected area is less than 0.5km2, it makes 0.5. When it is 0.5km2 and more, it has rounded at
the 1km2 unit.

-11-

3.3.2 Population affected by tsunami
NILIM and BRI estimated tsunami affected population and households. The way of
estimation is as follows: firstly calculate the ratio of tsunami affected area on each basic
unit blocks of national census, and then multiply that ratio by the number of population andhouseholds on each basic unit blocks, finally sum up those numbers on each prefecture. Inthat estimation, we used two data as follows: i) Tsunami boundary data made by GSI and ii)
Preliminary counts of 2010 population census made by Ministry of Internal Affairs andCommunications of Japan . The result is shown in Table 3.3-2.
Table 3.3-2 Estimated tsunami affected population and households
Prefecture/ Municipalities
Aomori
Hachinohe city
Misawa city
Rokkasho village
Oirase town
Higashidori village
Hashikami town
Iwate
Miyako city
Ofunato city
Kuji city
Rikuzentakata city
Kamaishi city
Otsuchi town
Yamada town
Iwaizumi town
Tanohata village
Fudai village
Noda village
Hirono town
MiyagiSendai city;
Miyagino ward
Sendai city;
Wakabayashi ward
Sendai city;
Taihaku ward
Ishinomaki city
Shiogama city
Kesennuma city
Natori city
Tagajo city
Iwanuma city
Higashimatsushima city
Watari town
Yamamoto town
Matsushima town
Shichigahama town
Rifu town
Onagawa town
Minamisanriku town
Fukushima
Iwaki city

Percentage of tsunami affected(%)
Estimated tsunami affected
Population and households of
population and households (a)tsunami affected municipalities (b)*2(a)／(b)×100
Population*1
Households*1
Population
Households
Population*1
Households*1
4,794
1,625
335,968
129,666
1.4
1.3
1,995
706
237,473
91,925
0.8
0.8
542
166
41,260
16,246
1.3
1.0
837
301
11,092
4,751
7.5
6.3
1,023
320
24,188
8,329
4.2
3.8
43
15
7,253
2,710
0.6
0.6
355
117
14,702
5,705
2.4
2.1
54,025
21,274274,114
101,900
19.7
20.9
11,581
4,799
59,44222,504
19.5
21.3
8,325
3,324
40,73814,814
20.4
22.4
2,488
960
36,87514,015
6.7
6.8
8,379
3,014
23,302
7,794
36.0
38.7
5,896
2,520
39,57816,095
14.9
15.7
8,214
3,244
15,277
5,674
53.8
57.2
6,834
2,594
18,625
6,605
36.7
39.3
262
100
10,804
4,355
2.4
2.3
219
77
3,843
1,309
5.7
5.9
46
17
3,088
1,042
1.5
1.7
1,353
477
4,632
1,576
29.2
30.3
427
148
17,910
6,117
2.4
2.4
242,573
87,056
1,205,851
466,356
20.1
18.7
14,932

5,537

190,485

85,790

7.8

6.5

7,313

2,092

132,191

58,891

5.5

3.6

1,246

427

220,715

91,5850.6

0.5

90,854
11,89819,985
11,18615,172
7,275
28,638
11,201
7,818
1,812
4,491
61
3,323
5,369
32,996
14,41334,750
4,490
7,376
3,654
6,038
2,049
9,615
3,315
2,513
668
1,363
22
1,341
1,805
10,3695,118

160,704
56,49073,494
73,14062,97944,19842,90834,846
16,711
15,08920,41934,00010,051
17,431
527,573
342,198

57,812
20,31425,46425,15024,047
15,53013,995
10,899
5,233
5,149
6,415
10,8193,968
5,295
191,906
128,516

56.5
21.1
27.2
15.3
24.1
16.5
66.7
32.1
46.8
12.0
22.0
0.2
33.1
30.8
6.3
4.2

60.1
22.1
29.0
14.5
25.1
13.2
68.7
30.4
48.0
13.0
21.2
0.2
33.8
34.1
5.4
4.0

-12-

Soma city
5,738
1,572
37,796
13,240Minamisoma city
6,334
1,681
70,89523,643Hirono town
407
132
5,418
1,810
Naraha town
498
143
7,701
2,576
Tomioka town
467
187
15,996
6,141
Okuma town
155
49
11,511
3,955
Futaba town
416
123
6,932
2,393
Namie town
2,131
610
20,908
7,171
Shinchi town
2,437
753
8,218
2,461
Ibaraki
13,181
4,783
963,774
377,878
Mito city
256
87
268,818
111,992
Hitachi city
2,901
1,074
193,129
77,932
Takahagi city403
160
31,014
11,656
Kitaibaraki city
3,370
1,257
47,026
16,965
Hitachinaka city
2,329
869
157,01260,276
Kashima city
824
242
66,03025,222Kamisu city
573
179
94,82335,760
Hokota city414
130
50,161
16,946
Oarai town
1,724
651
18,331
7,020
Tokai village
386
134
37,43014,109
Chiba
9,958
3,509
366,965
128,986
Choshi city277
128
70,22526,948Asahi city
3,686
1,288
69,074
23,121
Sosa city
658
210
39,826
12,869Sammu city
2,515
830
56,086
19,297
Oamishirasato town
150
57
50,122
18,117
Kujukuri town
1,475
556
18,009
6,617
Yokoshibahikari town
363
124
24,6798,278
Ichinomiya town
306
123
12,042
4,452
Chosei village
20
714,751
5,030
Shirako town
509
185
12,151
4,257
Total
357,526
128,616
3,674,245
1,396,692
Notes: *1 This result does not mean real damage situation, number of victim, and number of refugees.
*2 Population and households of tsunami unaffected municipalities are not included.

15.2
8.9
7.5
6.5
2.9
1.3
6.0
10.2
29.7
1.4
0.1
1.5
1.3
7.2
1.5
1.2
0.6
0.8
9.4
1.0
2.7
0.4
5.3
1.7
4.5
0.3
8.2
1.5
2.5
0.1
4.2
9.7

3.4 Inspections of Damaged Buildings and Residential Lands
3.4.1 Post-earthquake quick inspection of damaged buildings
The post-earthquake quick inspection of damaged buildings aims to quickly identify
the damage level of a building according to the observed damage status and to categorize
each damage level into one of three different groups related to potential hazards which
would be caused by aftershocks and so on3-6). As of June 2, 2011, 95,227 judgments havebeen conducted in 10 prefectures (149 municipalities) and 11,587 of them were judged
UNSAFE (RED). The inspection required a total of 8,515 man-days. Table 3.4-1 shows theinterim result of the inspection3-7).

-13-

11.9
7.1
7.3
5.6
3.0
1.2
5.1
8.5
30.6
1.3
0.1
1.4
1.4
7.4
1.4
1.0
0.5
0.8
9.3
1.0
2.7
0.5
5.6
1.6
4.3
0.3
8.4
1.5
2.8
0.1
4.3
9.2

Table 3.4-1

Result of Post-earthquake Quick Inspection of Damaged Buildings3-7)

Prefecture

Total
UNSAFE （RED）
LIMITED ENTRY （YELLOW）
INSPECTED （GREEN）
Iwate
168
445
459
1,072
Miyagi
5,088
7,511
37,96850,567
Fukushima
3,314
6,718
5,775
15,807
Ibaraki
1,561
4,684
9,618
15,863
Tochigi
676
1,845
2,658
5,179
Gunma
30
61
19
110
Saitama
0
42
83
125
Chiba
677
1,625
3,213
5,515
Tokyo
59
137
252
448
Kanagawa
14
81
446
541
Total
11,587
23,14960,491
95,227
Note: It should be noted that: 1) inspection was hardly executed in the tsunami affected areas, 2) the comprehensive
inspection was not carried out because there were a lot of damaged buildings in extensive areas, and 3) the result also
includes the number of damage to non-structural elements.

3.4.2 Post-earthquake quick inspection of damaged residential lands
Similar to the case of damaged buildings, post-earthquake quick inspection isconducted at damaged residential lands. The post-earthquake quick inspection of damaged
residential lands aims to quickly identify the damage level of a residential land according tothe observed damage status and to categorize each damage level into one of three different
groups related to potential hazards which would be caused by aftershocks and so on. Until
July 10, 2011, 6,313 judgments have been conducted in 9 prefectures (52 municipalities)
and 1,449 of them were judged UNSAFE (RED). Table 3.4-2 shows the interim result of
the inspection3-8).
Table 3.4-2 Result of Post-earthquake Quick Inspection of Damaged Residential Lands3-8)
Prefecture
Iwate
Miyagi
Fukushima
IbarakiTochigi
Gunma
Saitama
Chiba
Niigata
Total

UNSAFE （RED）
114
886
269
30
101
24
0
10
15
1,449

LIMITED ENTRY （YELLOW）
103
1,470
258
64
244
9
27
18
12
2,205

INSPECTED （GREEN）
162
1,640
484
41
133
7
104
9
79
2,659

Total
379
3,996
1,011
135
478
40
131
37
106
6,313

3.5 Temporary Housing
In order to provide disaster victims with decent and stable living environments, local
governments have been constructing temporary houses in the affected regions andproviding the evacuees with information on available rental housing units across Japan.
3.5.1 Construction of temporary housing
According to the Disaster Relief Act, prefectural governments are in charge of-14-

providing temporary housing for individuals and families who have been displaced by adisaster and the central government provide financial assistance to these governments.
Table 3.5-1 shows the progress of temporary housing construction3-9).
Table 3.5-1 The Progress of Temporary Housing Construction3-9)Prefecture

Total Number of Housing Units
Estimated to be Necessary

Iwate
Miyagi
Fukushima
IbarakiTochigi
Chiba
NaganoTotal

13,83322,43514,0001020
230
55
50,583In the Planning Stage
NumberNumber ofof Sites
housing units
―
―
15
1,844
―
―
―
―
―
―
―
―
―
―
15
1,844

Under Construction
NumberNumber ofof Sites
housing units
312
13,833358
19,918152
13,487
2
10
1
20
3
230
2
55
830
47,553Completed
Number of
Sites
11,527
15,985
10,1351020
230
55
37,962

3.5.2 Information Provision Related to Available Rental Housing Units
Local and central governments have provided information on available public andprivate rental housing. The Ministry of Land, Infrastructure, Transport and Tourism (MLIT)
set up the Center for Information on Public Houses for the Affected on March 22. Throughthe center and in cooperation with relevant ministries and private rental housing and realestate associations, MLIT has provided the displaced individuals and families withinformation on available public and private rental housing across Japan, including national
public officers’ housing, employment promotion housing, the Urban Renaissance (UR)
Agency’s housing and private rental housing.
Table 3.5-2 shows the approximate number of available housing units and those thatwere already allocated to displaced people in early July3-10). It is notable that the Japanese
government decided to reimburse the prefectures’ costs of renting private housing for those
who had been displaced by the disaster. As a result, more than 40,000 private rental housing
units were allocated to the displaced. Including newly constructed ones, approximately
85,000 housing units were already allocated or at least ready for the allocation.
Table 3.5-2 Housing Units Available for the Displaced3-10)
Total
Tohoku-region
Public Housing*1
23,0001,800
UR’s Rental Housing
5,100
130
Private Rental Housing
―
―
Total
―
―
Note: *1 Public housing includes national public officers’ housing and employment promotion housing.

Already Allocated
6,200
810
42,30047,3003.6 Building Restrictions
3.6.1 Building Restrictions based on the Building Standard Law of Japan
In order to prevent uncoordinated constructions of buildings in the affected areas,-15-

Miyagi Prefecture and Ishinomaki city designated the building restricted areas on April 8
and restricted building construction works within these areas, pursuant to Article 84 of the
Building Standard Law of Japan. Based on this law, Ishinomaki city has the same sort ofauthority over building regulations under an agreement with Miyagi prefecture. On April 12,
the deadline of building restrictions was extended to May 11. Designated areas include
Ishinomaki city, Kesennuma city, Natori city, Higashi-matsushima city, Onagawa town, andMinami-Sanriku town in Miyagi prefecture.
3.6.2 Enactment of New Law concerning Building Restrictions"Law on Special Provisions of building restrictions in the urban areas severely
damaged by the Great East Japan Earthquake" was established on April 28, which tookeffect as issued on the 29th. This law made it possible to implement building restrictions up
to eight months from the date of the disaster in the affected areas. Based on this law, on
May 11, Miyagi Prefecture and Ishinomaki city extended the period of building restrictionsin these designated areas until September 11.
References3-1) Japan Meteorological Agency (JMA). (June 23, 2011). JMA seismic intensity in the2011 off the Pacific coast of Tohoku earthquake (3rd report).
3-2) National Police Agency of Japan. (July 11, 2011). Damage Situation and Police
Countermeasures associated with 2011 Tohoku district - off the Pacific Ocean
Earthquake.
3-3) Cabinet Office, Government of Japan. (July 6, 2011). The Number of Evacuees
across Japan.
3-4) Fire and Disaster Management Agency. (July 7, 2011). The 131th Daily Report on
the 2011 off the Pacific coast of Tohoku Earthquake.
3-5) Geospatial Information Authority of Japan (GSI). (Apr 18, 2011). Tsunami affectedarea (5th report).
3-6) The Japan Building Disaster Prevention Association. Postearthquake Quick
Inspection of Damaged Buildings. Retrieved August 12, 2011, fromhttp://www.kenchiku-bosai.or.jp/english/file/epanfall.PDF
3-7) Ministry of Land, Infrastructure, Transport and Tourism (MLIT). (June 2, 2011).
Quick Inspections of Damaged Buildings.
3-8) Ministry of Land, Infrastructure, Transport and Tourism (MLIT). (July 11, 2011).
The Great East Japan Earthquake (the 81st report).
3-9) Ministry of Land, Infrastructure, Transport and Tourism (MLIT). (July 11, 2011).
The Progress of Temporary Housing Construction.
3-10) Ministry of Land, Infrastructure, Transport and Tourism (MLIT). (July 11, 2011).
The Progress of Policy Measures taken by the Housing Bureau.

-16-4. Outline of Earthquake and Tsunami
An Mw 9.0 (Mw by JMA) earthquake occurred off the Pacific Coast of Tohoku at
14:46 JST (5:46 UTC) on March 11, 2011 and generated gigantic tsunami in the
Tohoku and Kanto districts of the northeastern part of Japan. This was a thrustearthquake occurring at the boundary between the North American and Pacific plates.
An Mw 7.5 foreshock preceded the mainshock on March 9 and many large aftershocks
including two Mw 7-class aftershocks followed the mainshock.
4.1 Earthquake Mechanism
Many researchers are studying source process of the 2011 Tohoku earthquake
using different kinds of data, such as seismic waves, aftershocks’ locations, GPS,tsunami, etc. Here shows as an example the first result for the source process fromregional strong motion data by Yoshida et al. (2011)4-1). The main features are as
follows. (a) The main rupture is located to the east of the initial break point (theshallower side of the hypocenter), and maximum slip amounts were more than 25 m. (b)The size of the main fault was about 450 km in length and 200 km in width; theduration of rupture was more than 150 s; andMw was 9.0. (c) The initial rupture gradually
expanded near the hypocenter (0–40 s) andsubsequently propagated both southward
and northward.
Other analyses show more or less very
similar results to this result shown in Fig.
4.1-1. A result by tsunami inversion isshown in section 4.4.2.
Fig. 4.1-1 Finite-source model frominversion of strong motion waves4-1). (a)Moment rate function. (b) Slip distribution
on the fault. Large green star represents theepicenter of the mainshock, and gray circles
represent aftershocks (M ≥ 5.0) within 24 hof the mainshock. Triangles denote seismic
stations used in this analysis. Contour
interval in slip distribution is 4 m. The light
blue rectangle shows the estimated peak of
the highly uplifted area obtained fromtsunami arrival times.

-17-

4.2 Relocation of Earthquakes
Foreshocks, mainshock, and aftershocks of the 2011 Tohoku earthquake (Mw 9.1
by global CMT) were relocated using the modified joint hypocenter determination(MJHD) method4-2) in order to obtain their precise hypocenters and to identify fault
planes of larger earthquakes. P-wave arrival times at stations worldwide reported by the
U. S. Geological Survey (USGS) were used. It was confirmed by relocated hypocentersthat the mainshock and aftershocks had occurred along the plate boundary between the
North American and Pacific plates (Fig. 4.2-1). It was also confirmed that the Mw 7.5
foreshock, which occurred two days before the mainshock, and the largest aftershock(Mw 7.9), which occurred half an hour after the mainshock, were thrust earthquakes
along the plate boundary. The second largest aftershock (Mw 7.6), which was anormal-faulting earthquake and was a bending-stress intra-plate event caused by thestrain reduction on the subduction thrust, occurred at the outer rise of the Japan Trench
and was well relocated with its aftershocks. It was found that its fault plane dippedwestward and it bounded the aftershock distribution on the seaward side. This implies
that the western side of the fault plane had subsided, corresponding with the westward
plate subduction. The size of the one-day aftershock area is ~450 km x ~150 km if theouter rise area is excluded. If the outer rise area is included, the size is ~450 km in thenortherly direction and ~400 km in the easterly direction. The details of these analyses
are given by Hurukawa (2011) 4-3).
Magnitude
6

7

Magnitude

Depth

8

0

15

30

5

45

6

7

8

Magnitude

Depth
0

15

30

5

45

6

7

8

d) Outer Rise, Mw 7.6
Magnitude

Depth
0

15

30

5

45

C
A

B

MS

146°E

0 A
B
50
100
150
-200 -100 0 100 200 300
Distance (km)Depth (km)Depth (km)

144°E

0 A
20
40
60
80
-100

30

45

143°E

0
50
Distance (km)

B
D

B
D

37°N

35°N

140°E
B

-50

36°N

JT

JT
JT
142°E

15

38°N A

D

100

Depth (km)

38°N

142°E
140°E

0

C

Ibaraki

38°N

36°N

Depth

8

39°N

A

B
D

7

37°N
C

C
A

6

JT

Fukushima
39°N
40°N

141°E

143°E

142°E

B
0 A
20
40
60
80
100
-150 -100 -50 0
50 100 150
Distance (km)Depth (km)5c) Off Ibaraki, Mw 7.9b) Foreshock, Mw 7.5a) Mainshock, Mw 9.1

144°E

145°E

146°E

B
0 A
20
40
60
80
100
-150 -100 -50 0
50 100 150
Distance (km)Fig. 4.2-1 Relocated hypocenters by the MJHD method4-3). Epicentral distribution and a
vertical cross section along A-B line, which is perpendicular to strike of the nodal planeof the global CMT solution, are shown. This nodal plane corresponds with the fault
plane. a) The mainshock (2011/03/11 5:46 UTC) and immediate aftershocks within 24
hours. b) The largest foreshock (2011/03/09 2:45 UTC) and its aftershocks. MS indicate
the mainshock. c) The largest Mw 7.9 aftershock off Ibaraki (2011/03/11 6:15 UTC) andaftershocks within 24 hours after the mainshock. d) The Mw 7.6 aftershock at the outerrise (2011/03/11 6:25 UTC) and aftershocks. JT: Japan Trench.

-18-

4.3 High Frequency Energy Radiation Duration and its Corresponding Magnitude
Durations of high frequency energy radiation (HFER) measured from tele-seismic
P waves well correlate with source times, and can be used as their guesses. HFER
durations of the 2011 Tohoku earthquake were measured using broadband waveforms
recorded at the Global Seismograph Network stations; we retrieved data from the data
management center of the IRIS (Incorporated Research Institutions for Seismology).
Figure 4.3-1 shows the measured HFER durations as a function of station azimuths.
Their mean is 170.5 s. This suggests that the source time of this event is around 3
minutes. The azimuthal dependence shown in Fig. 4.3-1 suggests that the rupture which
generated strong HFERs propagated in the southwest direction.
The magnitude of this event was calculated using the following formula of Hara(2007) 4-4):(Eq.4.3-1)
M  0.79 log A  0.83 log   0.69 log t  6.47
where M is an earthquake magnitude, A is the maximum displacement (m)during the estimated duration of HFER from the arrival time of a P-wave,  is theepicentral distance (km), t is the estimated duration (s) of HFER. The mean of thecalculated magnitudes for all the stations is 8.96. Figure 4.3-2 shows the contribution of
the first and second terms (i.e., maximum displacement with distance correction) andthat of the third term (i.e., HFER duration) for this event and other large (Mw≧8)
shallow earthquakes that occurred since 1994. Compared to the December 26, 2004
Sumatra earthquake (Mw 9.0-9.3), the HFER duration of this event is shorter, while themaximum displacement is larger. The details of these analyses are given by Hara(2011)4-5).

Fig. 4.3-1 The measured HFER durations as a

Fig. 4.3-2 Contributions to magnitudes fromfunction of station azimuths. The moving

maximum displacement amplitudes andwindow (±30 degree) averages are shown.

epicentral distances (the horizontal axis) andthose from HFER durations (the verticalaxis).

-19-

4.4 Tsunami
4.4.1 Observed tsunami heights
The 2011 Tohoku tsunami was recorded instrumentally at four types of gauges.
They are ocean bottom tsunami sensor (OBTS), GPS gauge, wave gauge (WG) and tidegauge (TG), which are installed in deep to shallow sea. Japan Meteorological Agency(JMA) reported the tsunami heights observed at coastal tide gauges (Fig. 4.4-1).
According to JMA (2011) 4-6), the tsunami heights were less than 3 m along the coastsof Hokkaido to Aomori prefectures, and more than 4 m along the coasts of Iwate,
Miyagi and Fukushima prefectures. Many coastal tide gauges on the Pacific coast of the
Tohoku region stopped recording after the first tsunami arrival, because of power failureor the stations were damaged by the tsunami. Later JMA retrieved the tide gauge
records on site and announced that the observed tsunami heights were more than 8.5 m
at Miyako, more than 8.0 m at Ofunato, more than 7.6 m at Ayukawa (Ishinomaki), andmore than 9.3 m at Soma.

Fig. 4.4-1 Observed tsunami heights at tide gauge stations as of March 13th 8 AM4-6).
Tsunami heights in the coastal areas of Japan were measured and reported by the2011 Tohoku Earthquake Tsunami Joint Survey Group which consists of coastal
engineers, seismologists, tsunami researchers from universities or research institutes,
and other tsunami-related officials. The field surveys were mainly conducted along the
Pacific coasts from Hokkaido to Okinawa. The survey results all end up on the internet
site and are being updated appropriately4-7). According to the preliminary survey results,
inundation or runup heights were about 5 m in the Pacific coasts of Hokkaido, up to 10-20-

m in Aomori and Chiba prefectures, more than 30 m in some locations along theSanriku coasts of Iwate, up to 20 m in Miyagi prefecture (Fig. 4.4-2, as of 5 July 2011).

Fig. 4.4-2 Distribution of measured tsunami heights by the field surveys4-7). Red circles
and blue triangles indicate inundation heights and runup heights, respectively.
4.4.2

Tsunami source model and simulated maximum tsunami heights

A tsunami waveform inversion was performed to estimate the tsunami source ofthe 2011 Tohoku earthquake4-8). The tsunami waveforms were recorded at various typesof sensors such as OBTSs of Deep-ocean Assessment and Reporting of Tsunamis(DART) by National Oceanic and Atmospheric Administration (NOAA), cabled OBTSs
by Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and
Earthquake Research Institute (ERI), University of Tokyo, GPS wave gauges, tide andwave gauges by Japan’s Nationwide Ocean Wave information network for Ports and
HArbourS (NOWPHAS) and tide gauges of JMA and Japan Coast Guard (JCG). The
stations used for the tsunami waveform inversion are shown in Fig. 4.4-3.

-21-

Fig. 4.4-3 Epicenter of the 2011 Tohoku earthquake (red star), W phase MT solution by
USGS, and stations that recorded the tsunami4-8). Triangles, diamonds and squares
indicate the locations of coastal (tide or wave) gauges, offshore GPS wave gauges and
OBTSs or DART systems, respectively. Colors indicate operating agencies (yellow:
JMA, blue: JCG, green: JAMSTEC, orange: NOAA, light blue: NOWPHAS, andpurple: ERI). Square indicates the region shown in Fig.4.4-4.
Forty subfaults are located within the aftershock area (see Fig. 4.4-4). The length
and width are 50 km × 50 km for each subfault. The focal mechanisms of the all
subfaults are strike:193º, dip:14º and slip:81º from the USGS’s Wphase moment tensor
solution. The top depths of the subfaults were assumed to 0 km, 12.1 km, 24.2 km and36.3 km for near-trench, shallow, middle and deep subfaults, respectively. An
instantaneous rupture was assumed on the fault.
In order to calculate the Green's functions from source to stations, static
deformations of the seafloor, the initial conditions for tsunami, were calculated for arectangular fault model4-9) for each subfault. The used bathymetry data are 30
arc-second grid from JTOPO30 for tide gauges in Japan and 2 arc-minute grid for off
shore (Pacific Ocean), resampled from GEBCO_08 30 arc-second grid data. To
calculate tsunami propagation, the linear shallow-water, or long-wave, equations werenumerically solved by using a finite-difference method4-10).
The inversion result (Fig. 4.4-4) shows a tsunami source length (with more than 2m slip) of about 350 km, extending from over southern Sanriku-oki, Miyagi-oki,
Fukushima-oki as well as near the trench axis. The largest slips with more than 40 m are
estimated along the Japan trench axis off southern Sanriku. Around the epicenter, in-22-southern Sanriku region, the estimated slip is about 28 – 34 m. On the deeper subfault in
Miyagi-oki region, the slip is 9 – 23 m. To the north of the epicenter, 5 – 11 m slip is
estimated in a part of central Sanriku region. To the south, the slip is about 10 m in
Fukushima-oki region, and less than 3 m in Ibaraki-oki region. The total seismic
moment was calculated from these slip distributions as 3.8 × 1021 Nm (Mw 9.0) which isconsistent with other studies based on seismic data analyses. The comparison of tsunami
waveforms are shown in Fig. 4.4-5.

Fig. 4.4-4 (a) Slip distribution estimated by tsunami waveform inversion4-8). The
subfault numbers are shown in the northernmost and southernmost subfaults. Star shows
the mainshock epicenter. Circles indicate aftershocks within one day after themainshock (JMA data). Dashed lines indicate regions where the probabilities and size of
future subduction-zone earthquakes were estimated by Earthquake Research Committee(2009) 4-11). Coastal and offshore stations (the same symbol as Fig. 4.4-3) are also
shown. (b) Seafloor deformation computed from the estimated slip distribution. The redsolid contours indicate uplift with the contour interval of 1.0 m, whereas the blue
dashed contours indicate subsidence, with the contour interval of 0.5 m. The light blueand dark green frames show the subfaults with more than 2 m slips located near the
trench axis and in deep interplate, respectively.

-23-

Fig. 4.4-5 Comparisons of the observed (red curves) and synthetic (blue curves) tsunami
waveforms computed from the estimated slip distribution4-8). Time ranges shown bysolid curves are used for the inversions; the dashed parts are not used for the inversions,but shown for comparison. Note the same vertical scales for bottom pressure gauges(the upper left two columns), GPS wave gauges (upper central two columns) and coastaltide and wave gauges (upper right one column and bottom columns). See Figs.4.4-3 and4.4-4(a) for the station locations.

-24-

The tsunami heights were simulated along the Japanese coasts adopting thetsunami source model described above. The non-linear shallow-water equations werenumerically solved by using a finite-difference method4-10). The used bathymetry grid isthe 30 arc-second uniform grid from JTOPO30 data. The reproduced tsunami heights
were about 5 – 10 m along the coasts from southern part of Iwate to Fukushima andmore than 10 m in some locations such as a tip of peninsula or a back of bay (Fig.
4.4-6).

Fig. 4.4-6 Simulated tsunami heights along the coasts from southern part of Iwate to
Fukushima prefectures. The used tsunami source model is based on Fujii et al. (2011)
4-8).
References4-1) Yoshida, Y., H. Ueno, D. Muto, and S. Aoki, Source process of the 2011 Off the
Pacific Coast of Tohoku earthquake with the combination of teleseismic and strong
motion data, Earth Planets Space, 63, 2011, in press.
4-2) Hurukawa, N., Quick aftershock relocation of the 1994 Shikotan earthquake and its
fault planes, Geophy. Res. Lett., 22, 3159–3162, 1995.
4-3) Hurukawa, N., Relocation of the 2011 Off the Pacific Coast of Tohoku earthquake
sequence and fault planes of M ≥ 7 earthquakes, Earth Planets Space, 63, 2011, inpress.
4-4) Hara, T., Measurement of duration of high-frequency energy radiation and its
application to determination of magnitudes of large shallow earthquakes, Earth
Planets Space, 59, 227–231, 2007.
4-5) Hara, T., Magnitude determination using duration of high frequency energy
radiation and displacement amplitude: application to the 2011 Off the Pacific Coast-25-

of Tohoku Earthquake, Earth Planets Space, 63, 2011, in press.
4-6) Japan Meteorological Agency, Press Release "2011 off the Pacific coast of Tohoku
Earthquake
(No.
14)",
http://www.jma.go.jp/jma/press/1103/13a/kaisetsu201103130900.pdf, 2011 (inJapanese).
4-7) The 2011 Tohoku Earthquake Tsunami Joint Survey Group, The 2011 off the
Pacific
coastof
TohokuEarthquake
TsunamiInformation,
http://www.coastal.jp/tsunami2011/, 2011.
4-8) Fujii, Y., K. Satake, S. Sakai, M. Shinohara and T. Kanazawa, Tsunami source ofthe 2011 off the Pacific coast of Tohoku, Japan earthquake, Earth Planets Space,63, 2011, in press.
4-9) Okada, Y., Surface Deformation Due to Shear and Tensile Faults in a Half-Space,
Bulletin of the Seismological Society of America, 75, 1135-1154, 1985.
4-10) Satake, K., Linear and Nonlinear Computations of the 1992 Nicaragua
Earthquake Tsunami, Pure and Applied Geophysics, 144, 455-470, 1995.
4-11) Earthquake Research Committee, Long-term forecast of earthquakes from
Sanriku-oki to Boso-oki (revised) (in Japanese), Headquarters for Earthquake
Research Promotion, 80pp, 2009.

-26-

5. Earthquake Motions and Strong Motion Observation in Buildings
5.1 Distribution of Seismic Intensities
Figure 5.1-1 shows the distribution of JMA seismic intensities recorded during the2011 Tohoku earthquake. An asterisk represents the location of the epicenter. Intensity 7
was recorded in Kurihara city, Miyagi prefecture, and JMA intensity 6 upper (6+) wasrecorded in wide area of Miyagi, Fukushima, Ibaraki, and Tochigi prefectures. Area of
JMA intensity 6 lower (6-) extends to Iwate, Gunma, Saitama, and Chiba prefectures in
addition to Miyagi, Fukushima, Ibaraki, and Tochigi prefectures.
44˚
43˚
42˚
41˚

IJMA
7
6
5
4
3
2
1

40˚
39˚
38˚
Main shock
2011/03/11 14:46(h=24km, Mw9.0)

37˚
36˚

km

35˚
0

34˚
134˚ 135˚ 136˚ 137˚ 138˚ 139˚

Fig. 5.1-1

100

200

140˚ 141˚ 142˚ 143˚ 144˚ 145˚ 146˚

Distribution of JMA seismic intensity

5.2 Characteristics of Earthquake Motions
When the 2011 Tohoku earthquake occurred, severe ground shakings wereobserved in wide area, and massive amount of strong motion records were accumulated.
This section describes the characteristics of the strong motion records at observation
stations that suffered high seismic intensities, based on the strong motion network
K-NET of the National Research Institute for Earth Science and Disaster Prevention(NIED)5-1). Fig. 5.2-1 shows acceleration waveforms and pseudo velocity response
spectra with damping ratio of 5% of strong motion records at K-NET Tsukidade station-27-

that recorded Intensity 7, and K-NET Sendai and K-NET Hitachi stations among
Intensity 6+ stations, with the locations of the stations.

60

80

140

60

80

141˚

142˚

0
10
0

0

0
10
)
(c
m
/s/
s
10

10
0
10
(c
m
/s/
s)

N-S
E-W
U-D

0.1

0.5
1
Period (sec)

510500 Pseudo Vel. Resp. Spectrum (h=5%)N-S (peak:- 1599 cm/s2)

E-W (peak:- 1187 cm/s2)

0

U-D (peak: 1159 cm/s2)

0

20

40

IBR003: K-NET Hitachi

60

80

100
120
Time (sec)

140

160

180

200

0
10

10
5
2

N-S
E-W
U-D

0.1

1

0

50

)
cm
1(
0.

-3000

100

(c
m
/s/
s)

(cm/s2)143˚(cm/s2)

140˚

2

200

10

139˚

180

0

-3000
3000

138˚

160

0

35 ˚

140

5

10

(cm/s2)(cm/s2)(cm/s2)

100
120Time (sec)

10

0

40

50

10
0

20

-3000
3000

100

10
00
10

0

100

10

50

10

1

km

5

10

U-D (peak:- 299 cm/s2)0

MYG013: K-NET Sendai
3000 Acceleration

0

0.5
1
Period (sec)0
10

E-W (peak: 987 cm/s2)

0

-3000

36˚

0.1

500 Pseudo Vel. Resp. Spectrum (h=5%)

)
cm
1(
0.

K-NET Hitachi (6+)

200

0

-3000
3000

37˚

180

N-S (peak: 1520 cm/s2)

-3000
3000

K-NET Sendai (6+)

160

0(cm/s2)

38˚

100
120
Time (sec)

N-S
E-W
U-D

00

40

2

10

20

5

00
0

0

MYG004: K-NET Tsukidate
3000 Acceleration

10

1

-3000

K-NET Tsukidate (7)U-D (peak: 1886 cm/s2)

0

10

39˚

)
cm
1(
0.

(cm/s2)

-3000
3000

50

10
00

(cm/s2)0100

0E-W (peak:- 1285 cm/s2)

10

-3000
3000

Pseudo Velocity Response (cm/s)

143˚

142˚

141˚

Pseudo Velocity Response (cm/s)

140˚

500 Pseudo Vel. Resp. Spectrum (h=5%)N-S (peak: 2679 cm/s2)

0

Pseudo Velocity Response (cm/s)

139˚

40˚

(cm/s2)3000 Acceleration

138˚

0.5
1
Period (sec)510

Fig. 5.2-1 Acceleration waveforms and pseudo velocity response spectra recorded at
K-NET stations
K-NET Tsukidade, which is located in Kurihara city, Miyagi prefecture, is the
only station that recorded Intensity 7 during the main shock of the 2011 Tohoku
earthquake. From the acceleration records in the upper-row in Fig. 5.2-1, a maximum
acceleration in the N-S direction reached almost 3,700 cm/s2, representing that themainshock caused excessively severe earthquake motions. As seen from the pseudo
velocity responses on the right diagram, a response in the N-S direction with a period of
about 0.2 s becomes particularly large. This indicates earthquake ground motions thatare dominated by short periods.
K-NET Sendai, which is located about 4 km east from the JR Sendai Station,
recorded Intensity 6+ during the mainshock. A maximum acceleration in strong motion
records (mid-row in Fig. 5.2-1) obtained from the network exceeds 1,500 cm/s2 in the
N-S direction, indicating a higher level of the main shock. In contrast to K-NET
Tsukidate, earthquake motions that were recorded in K-NET Sendai are dominated by aperiod range of 0.5 to about 1 s, and a maximum response velocity exceeds 200 cm/s.
This result seems to reflect the ground condition around K-NET Sendai station that iscovered with thick alluvium.
The lower-row in Fig. 5.2-1 shows strong motion records that were obtained from
K-NET Hitachi in Hitachi city, Ibaraki prefecture. The seismic intensity with themainshock was 6+. The maximum acceleration in the N-S direction reached a higher-28-

level, or about 1600 cm/s2, while the pseudo velocity response spectra had a peak at
about 0.3 s. On the other hand, the response was sharply reduced at a period longer than
0.5 s. This indicates that the earthquake motions were dominated in short period range.
Both records of K-NET Tsukidate and K-NET Sendai show two wave groups atabout 20 and 70 seconds on the time axis, but the strong motion record obtained atmuch southern station such as K-NET Hitachi, Ibaraki prefecture in Kanto area shows
one large wave group. This phenomenon may have occurred associated with the focal
rupture process and the wave propagation to recording stations.
5.3 Results of BRI Strong Motion Observation Network
BRI conducts strong motion observation that covers buildings in major cities
across Japan5-2). When the 2011 Tohoku earthquake occurred, 58 strong motion
instruments placed in Hokkaido to Kansai started up5-2). Peak accelerations of the strong
motion records are listed in Table 5.3-1. Locations of the strong motion stations areplotted in Fig. 5.3-1 and Fig. 5.3-2. Among them, about 30 buildings suffered a shaking
with JMA intensity 5- or higher. This section presents some characteristics of strong
motion records.
The detailed data on the recorded motions from the BRI strong motion
observation network can be seen through the Internet at http://smo.kenken.go.jp/-29-

Table 5.3-1 Strong motion records obtained by BRI observation network (1/4)
CodeStation name [prefecture]Δ (km)IJMA

Azimuth

Loc.

B2F*
15F
01F*
192°
09F
01F
167° 07F
GL*
B1F*
180°
09F
01F*
182°
04F
GL*
G30
G105
164°
10F
01F
B1F
B1F*
164°
06F
08F
087°
B1F*
A01*
A89
BFE
180°
8FE
MBC
M8C
180° 01F*
B1F*
004° 01F
06F
B1F*
061°
07F

Max. Acc. (cm/s2)
H1
H2
V
163
259
147
361
346
543
333
330
257
908
728
640
138
122
277
246
197
359
174
174
240
175
176
147
579
449
260
34
36
14
37
39
15
286
210
61
86
89
49
36
46
32
120
123
206
91
122
73
100
104
58
97
110
55
348
335
78
175
192
44
50
47
24
279
227
248
142
153
102
194
191
136
597
506
344
203
206
152
682
585
311
281
273
165
327
233
122
92
76
198
126
91
243
28
40
14
39
55
14

SND

Sendai Government Office
Bldg. No.2 [Miyagi]

175

5.2

THU

Tohoku University [Miyagi]

177

5.6

MYK

Miyako City Hall [Iwate]

188

4.8

IWK

Iwaki City Hall [Fukushima]

210

5.3

TRO

Tsuruoka Government Office
Bldg. [Yamagata]

275

3.9

HCN2

Annex, Hachinohe City Hall
[Aomori]

292

5.2

HCN

Main bldg., Hachinohe City
Hall [Aomori]

292

4.6

AKT

Akita Prefectural Office [Akita]

299

4.3

ANX

Building Research Institute[Ibaraki]

330

5.3

BRI

Training Lab., BRI [Ibaraki]

330

5.4

TKC

Tsukuba City Hall
(Base-isolation) [Ibaraki]

334

5.2

NIG

Niigata City Hall [Niigata]

335

3.9

346

3.4

195° 01F*

28

25

15

357

5.1

000° 01F*

269

263

151

B1F
302° GL*
07F
GL*
288° 01F
06F
01F
258° GL*
07F

140
312
486
230
150
283
72
130
219

135
306
359
197
119
322
104
127
190

92
171
145
79
63
131
71
73
106

HRH
TUS

Hirosaki Legal Affairs Office[Aomori]
Noda Campus, Tokyo Univ. Of
Science [Saitama]

YCY

Yachiyo City Hall [Chiba]

361

5.3

NIT

Nippon Institute of Technology[Saitama]

362

5.1

MST

Misato City Hall [Saitama]

367

4.9

074°

Note) Δ: epicentral distance, IJMA : JMA instrumental seismic intensity (using an asterisked sensor), Azimuth:
clockwise direction from North, H1, H2, V : maximum accelerations in horizontal #1 (Azimuth), horizontal#2 (Azimuth+90°) and vertical directions-30-

Table5.3-1 Strong motion records obtained by BRI observation network (2/4)
CodeStation name [prefecture]Δ (km)IJMA

FNB

Educational Center, Funabashi
City [Chiba]

368

4.7

CHB

Chiba Government Office Bldg.
No.2 [Chiba]

369

4.9

ICK

Gyotoku Library, Ichikawa City
[Chiba]

375

5.2

EDG

Edogawa Ward Office [Tokyo]

377

4.8

ADC

Adachi Government Office
Bldg. [Tokyo]

377

4.8

SIT2

Saitama Shintoshin Government
Office Building No.2 [Saitama]

378

4.4

SITA

Arena, Saitama Shintoshin
Government Office Building[Saitama]

378

4.5

TDS

Toda City Hall [Saitama]

380

5.0

AKB

Akabane Hall, Kita Ward
[Tokyo]

380

4.6

SMD

Sumida Ward Office [Tokyo]

380

4.3

NMW

National Museum of Western
Art (Base-isolation) [Tokyo]

382

4.8

UTK

Bldg. No.11, University ofTokyo [Tokyo]

383

4.7

TKD

Kosha Tower Tsukuda [Tokyo]

385

4.4

CGC

Central Government Office
Bldg. No.6 [Tokyo]

386

4.4

CG2

Central Government Office
Bldg. No.2 [Tokyo]

386

4.2

CG3

Central Government Office
Bldg. No.3 (Base-isolation)[Tokyo]386

4.5

AzimuthLoc.

01F
357° GL*
08F
B1F
346° 08F
GL*
01F*
321° 02F
05F
01F*
003°
05F
01F*
012°
04F
B3F*
340° 10FS
27FS

Max. Acc. (cm/s2)
H1
H2
V
144
147
63
133
145
105
359
339
141
152
122
51
375
283
117
168
175
100
164
163
71
178
186
80
240
300
104
112
112
69
256
299
77
118
103
71
266
146
95
74
63
42
119
138
62
248
503
107

313° 01F*

90

105

47

GL*
354° B1F
08F
B1F*
354°
06F
20F
000° 08F
B1F*
GL*
B1FW
218°
01FW
04F
7FN
7FS
348°
01F
GL*
01F*
180° 18F
37F
01F*
208° 20B
19C
B4F*
208° 13F
21F
B2F*
208° B1F
12F

203
140
425
85
180
385
263
69
265
100
76
100
181
201
73
197
87
118
162
90
208
179
75
137
121
104
55
94

206
173
531
139
250
290
197
66
194
79
89
77
212
360
151
218
98
141
198
86
148
133
71
113
131
91
41
82

53
65
160
59
86
81
46
34
150
84
87
90
58
160
49
79
41
64
108
45
173
130
49
72
104
58
62
104

Note) Δ: epicentral distance, IJMA : JMA instrumental seismic intensity (using an asterisked sensor), Azimuth:
clockwise direction from North, H1, H2, V : maximum accelerations in horizontal #1 (Azimuth), horizontal#2 (Azimuth+90°) and vertical directions-31-

Table 5.3-1 Strong motion records obtained by BRI observation network (3/4)
CodeStation name [prefecture]Δ (km)IJMA

Azimuth

Loc.

B8F
B4F
354°
01F*
04F
G35
354° G24
GL*
01S*
354°
17S
06F
359°
01F*
01F
000° GL*
07F
03F
090° 01F
GL*
01F*
045° 02F
07F
B1F*
157°
11F

Max. Acc. (cm/s2)
H1
H2
V
61
88
53
68
101
56
76
104
84
125
192
94
72
71
51
95
116
54
224
201
93
70
94
60
458
489
111
172
375
56
126
158
54
174
169
60
181
189
71
316
223
66
129
329
55
110
136
53
167
143
50
107
77
30
133
123
49
366
304
76
8
7
8
35
27
9

Annex, National Diet Library
NDLA[Tokyo]387

4.5

Ground, National Diet Library[Tokyo]

387

5.0

387

4.5

390

4.8

390

5.0

401

4.6

401

4.7

444

2.7

447

3.5

180° GL*

25

28

13

466

2.7

468

3.9

140° 01F*
B1F
GL*
006°
01F
08F

17
47
51
37
41

20
39
44
52
51

8
18
20
20
25

517

2.9

225° GL*

12

19

10

520

4.2

165°

524

2.6

01F*
11F
B1F*
292°
6F
GL*
G10
G34
167°
B1F
01F
09F

28
81
9
32
12
10
5
8
10
16

40
56
10
31
14
10
5
12
16
19

15
18
8
10
6
4
3
4
6
12

NDLG
NDLM
NKN
TUF
KDI
KWS
NGN
HKD
HRO
YMN
SMS
SMZ
KSO

Main Bldg., National Diet
Library [Tokyo]
Nakano Branch, Tokyo Legal
Affairs Bureau [Tokyo]
Tokyo University of Marine
Science and Technology[Tokyo]College of Land, Infrastructure
and Transport [Tokyo]
Kawasaki-minami Office,Labour Standards Bureau[Kanagawa]
Nagano Prefectural Office[Nagano]Hakodate Development andConstruction Department[Hokkaido]
Hiroo Town Office [Hokkaido]
Yamanashi Prefectural Office(Base-isolation [Yamanashi]
Shimoda Office, Shizuoka
Prefecture [Shizuoka]
Shimizu Government Office
Bldg. [Shizuoka]
Kiso Office, Nagano Prefecture[Nagano]KGC

Kushiro Government Office
Bldg. (Base-isolation)[Hokkaido]

558

2.6

HKU

Hokkaido University[Hokkaido]

567

2.7

172° GL*

10

9

5

NGY

Nagoya Government Office
Bldg. No.1 [Aichi]

623

3.1#

GL*
174° B2F
12F

8
9
25

15
14
46

7
7

Note) Δ: epicentral distance, IJMA : JMA instrumental seismic intensity (using an asterisked sensor), Azimuth:
clockwise direction from North, H1, H2, V : maximum accelerations in horizontal #1 (Azimuth), horizontal#2 (Azimuth+90°) and vertical directions#: Calculated from two horizontal accelerations because of trouble on the vertical sensor.

-32-

Table 5.3-1 Strong motion records obtained by BRI observation network (4/4)
CodeStation name [prefecture]Δ (km)IJMA

AzimuthMTS

Matsusaka Office, Mie
Prefecture [Mie]

688

2.3

MIZ

Maizuru City Hall [Kyoto]

726

0.9

OSK

Osaka Government Office Bldg.
No.3 [Osaka]

759

2.9

SKS

Sakishima Office, Osaka
Prefecture [Osaka]

770

3.0

Max. Acc. (cm/s2)
H1
H2
V
16
8
4
6
5
3
1
2
2
1
1
2
65
38
7
11
9
5
35
33
80
41
38
61
85
57
18
127
88
13
129
85
12

Loc.

07F
01F*
01F
085°
05F*
18F
189°
B3F*
01F*
18F
229° 38F
52FN
52FS
216°

Note) Δ: epicentral distance, IJMA : JMA instrumental seismic intensity (using an asterisked sensor), Azimuth:
clockwise direction from North, H1, H2, V : maximum accelerations in horizontal #1 (Azimuth), horizontal#2 (Azimuth+90°) and vertical directions

44˚
43˚

HKU

KGC
HRO

42˚
HKD

41˚
HRH

40˚

HCN2, HCN
MYK

AKT

39˚

TRO

38˚

NIG

37˚

THU,
SND

2011/03/11
14:46(JST)h=24 km, M9.0

IWK
NGN

36˚
35˚

MIZ
OSK,
SKS
MTS

KSO
YMN
NGY SMZkm

SMS
0100 20034˚
134˚ 135˚ 136˚ 137˚ 138˚ 139˚
140˚ 141˚ 142˚ 143˚ 144˚ 145˚ 146˚

Fig. 5.3-1

Locations of epicenter () and BRI strong motion stations ( )-33-36˚20'

ANX, BRI
TKC
NIT

36˚00'

SITA, SIT2
UTK,
NMW,
SMD
KDI
35˚40'

TUS

MST
TDS
AKB
ADC
EDG

YCY
TKD ICKFNB
CHB
TUF

NKN

CGC,
CG2,
CG3 KWSkm
35˚20'
139˚20'0

139˚40'140˚00'50

140˚20'140˚40'Fig. 5.3-2 BRI strong motion stations in Kanto area
(corresponding to a rectangle in Fig. 5.3-1)
5.3.1

Strong motion records of damaged buildings

Among buildings in the BRI strong motion network, at least 4 buildings suffered
severe earthquake motions and then some damage. One example of the damagedbuildings is the research building of Civil Engineering and Architecture, Tohoku
University (Photo 5.3-1). This is the 9-story steel-framed reinforced concrete (SRC)
school building that is located in the Aobayama Campus of Tohoku University. Thisbuilding has a long history of strong motion observation. Among them, strong motion
records on the ninth floor of the building that were obtained in the 1978 Miyagi-ken-oki
earthquake are well known to have represented a maximum acceleration of more than
1,000 cm/s2.
During the Tohoku earthquake, multi-story shear walls suffered bending failure
and other damage. Strong motion records were obtained during the mainshock as shownin Fig. 5.3-3. Maximum accelerations on the first floor exceeded 330 cm/s2 in both ofthe directions. A maximum acceleration on the ninth floor was twice to three times
larger than that on the first floor, and exceeded 900 cm/s2 in the transverse direction.
The fundamental natural periods in Fig. 5.3-3 (e) represented about 0.7 s at the initialtime of the earthquake motion in both of the directions, but increased to about 1 s in thefirst wave group at the time of 40 to 50 s, and increased from 1.2 s to about 1.5 s in thesecond wave group at the time of 80 to 100 s. Due to the seismic damage, thefundamental natural period finally became twice longer than the natural period at theinitial stage. The stiffness of the building was reduced to 1/4.

-34-

Photo 5.3-1 The research building of Tohoku University-35-

Acc (cm/s2)

1000

Acc (cm/s2)
Disp (cm)(b) Acc. in Long. Dir.

09F(Long.)
01F(Long.)

0

−1000
40

(c) Bldg. Disp. in Trans. Dir.

0

−40
40
Disp (cm)

09F(Trans.)
01F(Trans.)

0

−1000
1000

(d) Bldg. Disp. in Long. Dir.

0

−40
2.0
T (s)

(a) Acc. in Trans. Dir.

(e) Transition of natural periods

1.5
1.0
Trans

0.5
0

50

100
Time (s)

150

Long.
200

Fig. 5.3-3 Strong motion records of the research building of Tohoku University andtransition of natural periods with time. (a) acceleration waveforms in the transverse
direction, (b) acceleration waveforms in the longitudinal direction, (c) building
displacement in the transverse direction (relative displacement to first floor of the
9-story building), (d) building displacement in the longitudinal direction, and (e)fundamental natural periods of the building that were calculated every 10 s5-3). Thickand thin lines in Fig. 5.3-3 (a) and (b) represent acceleration waveforms on the first andninth floors, respectively.
5.3.2

Long-period earthquake motions in Tokyo and Osaka

In Japan, long-period earthquake motions and responses of super high-risebuildings that are shaken under the motions have been socially concerned in recent
years. When the 2011 Tohoku earthquake occurred, long-period earthquake motions
were observed in Tokyo, Osaka and other large cities that were away from its
hypocenter. This section presents two cases in Tokyo and Osaka from the BRI
observation network.
Firstly, a 37-story reinforced concrete (RC) super high-rise building on the coastof Tokyo Bay is introduced. Fig. 5.3-4 shows waveforms of displacement (in two
horizontal directions of S-N and W-E) that were calculated from the integration ofacceleration records on the 1st and 37th floors in this building, and building
displacements that were calculated by subtracting the displacements on the 1st floor
from those on the 37th in the two horizontal directions. A maximum value of ground-36-

Disp. (cm)Disp. (cm)Disp. (cm)Disp. (cm)Disp. (cm)Disp. (cm)motion displacement was about 20 cm. It is understood that the ground itself was
greatly shaken. A displacement of the building caused by its deformation reached 15 to
17 cm.
Secondly, Figure 5.3-5 shows strong motion records that were obtained from the
55-story steel office building on the coast of Osaka Bay that is 770 km away from the
hypocenter. The figure represents absolute displacements in the SW-NE and in the
NW-SE on the 1st floor, absolute displacements in both of the directions on the 52nd
floor, and building displacements (relative displacements of 52th floor to 1st floor) inboth of the directions, from the top to the bottom. A ground motion displacement was
not large, or less than 10 cm, but the 52nd floor in the building suffered a large motion
with a zero-to-peak amplitude of more than 130 cm (displacement).
In order to examine the properties of earthquake motions on both of the coasts ofTokyo Bay and Osaka Bay, pseudo velocity response spectra with a dumping ratio of
5% of strong motion records that were obtained from the 1st floors in the buildings at
the two locations are shown in Fig. 5.3-6. The response spectrum (right) in the records
on the coast of Tokyo Bay had peaks at a period of 1 to 1.2 s, at 3 s and at 7 s, but arelatively flat shape in general.
On the other hand, the response spectrum (left) in the records on the coast of
Osaka Bay had a large peak at 7 s, and amplitude of the response was not muchdifferent from on the coast of Osaka Bay. The coincidence of the fundamental natural
period (6.5 to 7 s) in the office building with a predominant period of the earthquake
motion is considered to have caused a resonance phenomenon and then large building
motions.

Fig. 5.3-4

50

Displacement
01F S-N (peak:- 20.5 cm)

0
-50
50

01F W-E (peak:- 17.6 cm)

0
-50
50

37F S-N (peak:- 32.1 cm)

0
-50
50

37F W-E (peak:- 27.9 cm)

0
-50
50

37F-01F S-N (peak:- 14.7 cm)

0
-50
50

37F-01F W-E (peak:- 16.7 cm)

0
-50

0

100

200

300

Time (s)

400

500

600

700

Displacement waveforms observed at a 37-story residential building in-37-

Disp. (cm)Tokyo Bay area
200

Displacement
01F SW-NE (peak:- 9.1 cm)

0

Disp. (cm)0

Disp. (cm)0

Disp. (cm)0

Disp. (cm)0

Disp. (cm)

-200
200

0

01F NW-SE (peak: 7.8 cm)

-200
200

52F SW-NE (peak: 137.1 cm)

-200
200

52F NW-SE (peak:- 83.7 cm)

-200
200

52F-01F SW-NE (peak:- 138.2 cm)

-200
200

-200

52F-01F NW-SE (peak: 84.8 cm)

0

100

200

300

Time (s)

400

500

600

700

Fig. 5.3-5 Displacement waveforms observed at a 55-story office building in Osaka
Bay area. From the top to the bottom; absolute displacements in the SW-NE and in the
NW-SE on the 1st floor, absolute displacements in both of the directions on the 52nd
floor, and building displacements (relative displacements of 52th floor to 1st floor) inboth of the directions.

10

5

1(
cm
/s /
s)

1(
cm
/s /
s)

1

10
10

5

Pseudo Velocity Response (cm/s)

10

10

10
0

Osaka

50

10

Pseudo Velocity Response (cm/s)

Pseudo Vel. Resp. Spectrum (h=5%)

10
0

Tokyo

50

100

10
00

Pseudo Vel. Resp. Spectrum (h=5%)
10
00

100

1

1
Period (sec)

5

10

0.1

1
0.

0.5

0.5

)
m
(c
01
0.

0.1

S-N
W-E

1

1

)

1
0.

m
(c
01
0.

0.5

0.5

1
Period (sec)

SW-NE
NW-SE
5

10

Fig. 5.3-6 Pseudo response spectra with damping ratio of 5% of records in Tokyo Bay
area (left) and Osaka Bay area (right)-38-

References5-1) National Research Institute for Earth Science and Disaster Prevention K-NET,
http://www.k-net.bosai.go.jp/5-2) BRI Strong Motion Observation Network Website: http://smo.kenken.go.jp/5-3) T. Kashima and Y. Kitagawa: Dynamic Characteristics of Buildings Estimatedfrom Strong Motion Records, Proceedings of the 8th U.S. National Conference on
Earthquake Engineering, Paper No. 1136, December 2005

-39-

-40-

6. Damage to Buildings by Earthquake Motions
6.1 Policy on Earthquake Damage Investigation for Buildings
The 2011 Tohoku earthquake brought about building damage in a wide area ofvarious prefectures on the Pacific coast in eastern Japan such as Iwate, Miyagi,
Fukushima, Ibaraki and Chiba prefectures.
The epicentral area of this earthquake has a length of about 450 km and a width ofabout 150 km, almost in parallel with the Pacific coast in eastern Japan. Distance from thefault plane of the earthquake to the above prefectures is almost same. As indicated in
Chapter 5, observed earthquake motions in Sendai City close to the epicenter are notmuch different from those in cities far away from Sendai, for instance, Tsukuba City.
Based on these circumstances, NILIM and BRI decided to widely survey damaged
wooden buildings as a primary damage investigation in the northern part of Miyagi(Kurihara City) where JMA Seismic Intensity 7 was observed, and in a wide area of
Miyagi to Ibaraki including inland Tochigi prefecture that suffered larger damage thancoastal prefectures. In addition, as a secondary investigation, it was planned to selectaffected areas from those subject to the primary investigation to conduct a more detailed
survey on buildings collecting building plans and wood-shear-wall layout.
In order to conduct a damage investigation of steel buildings, it was decided thatmainly a primary visual inspection would be done in Sendai City with a large stock ofsteel buildings, and also in Fukushima and Ibaraki prefectures. As mentioned later,
severer damage to structural elements seemed to be limited, while there were so many
types of damage to nonstructural elements such as falling of exterior cladding.
Consequently, focusing not on private buildings that are difficult to investigate in detailbut on school gymnasiums in Ibaraki prefecture where many damage cases were reported
that enabled interior investigations, it was decided to continue the primary investigation.
For reference, the school gymnasiums can be seen to be similar to factories andwarehouses. If the structural damage in interior building is clarified in future, moredetailed secondary investigation on buildings other than the gymnasiums will beconsidered.
For a damage investigation for reinforced concrete buildings, in addition to an
investigation of reportedly collapsed buildings, a primary investigation will be conductedon city halls and other public buildings that are located in a wide area of the north to thesouth as done in the damage investigation for wooden buildings, and damage patterns
whether they are similar or different from previously grasped patterns are examined. If
there are characteristic damage patterns that should be incorporated into technicalstandards, the secondary investigation will be considered.
A primary investigation for damage of building lands and foundations will be
conducted in Itako City, Ibaraki, and in Urayasu City, Chiba and its peripheral areas that-41-

were subject to severe liquefaction in the region of Kanto. The areas that had been
affected by the 1978 Miyagi-Ken-Oki Earthquake were damaged again. In these areas,
also a primary damage investigation that focuses on developed housing lands will be
conducted in some areas of Miyagi, Fukushima and Tochigi prefectures.
In order to survey the damage of nonstructural elements, a primary investigation
will be performed, altogether with a damage investigation for steel and reinforced
concrete buildings including a requested investigation of ceiling falls in the Ibaraki
Airport Building as an administrative support.

-42-6.2 Damage to Wood Houses
6.2.1 Objectives of damage survey
A lot of wood buildings were damaged by the 2011 Tohoku earthquake. NILIM
and BRI surveyed the damage of wood building starting from March 14, to be threedays after the earthquake occurrence for the purpose of grasping the general image ofthe damage. Because the disaster by the earthquake occurred in wide areas, we carriedout the first survey for multiple times, but cannot grasp the whole aspect of the damage.
In this chapter, results of these multiple survey were summarized as basic documents todevise a survey plan in afterward to consider about the damage cause.
6.2.2 The selection of the survey area and the outline of the survey
The survey area and the reasons of the selection are as follows;
Kurihara city in Miyagi pref. : The seismic intensity 7 was recorded,
Osaki city in Miyagi pref. : As a result of damage survey6.2-1),
heavy damage was reported,
Sukagawa city in Fukushima pref.: RC buildings were heavily damaged,
Nasu and Yaita cities in Tochigi pref., and Hitachiota and Naka cities in Ibaraki pref. :As a result of damage survey6.2-1) by others, damage information has
never been reported, at the time of our survey,
Ishinomaki city in Miyagi pref. : Although it was almost included in the inundationarea, the selected area of the city was not inundated by the tsunami, and,Joso and Ryugasaki cities in Ibaraki pref. : There was damage information and they
are close to NILIM and BRI.
The locations of the surveyed cities and towns are shown in Fig. 6.2-1, and theschedules of the survey are shown in table 6.2-1.
Table 6.2-1 Schedules of survey.
Month/Day

Surveyed area

3/14～16

Kurihara and Sendai in Miyagi prefecture

3/23

Joso and Ryugasaki in Ibaraki prefecture

3/24～25

Sukagawa in Fukushima prefecture andNasu and Yaita in Tochigi prefecture

3/25

Hitachiota, Naka, and Mito in Ibaraki prefecture

4/21

Hitachiota and Naka in Ibaraki prefecture

4/27～29

Osaki, Misato, and Ishinomaki in Miyagi prefecture-43-

Kurihara city, Miyagi pref.
Osaki city
Misato town
Ishinomaki city
Aoba ward, Sendai city
Sukagawa city, Fukushima pref.
Nasu town, Tochigi pref.
Yaita city
Hitachiota city, Ibaraki pref.
Naka city
Mito city
Joso city
Ryugasaki city
Fig. 6.2-1 Locations of surveyed cities and towns.
6.2.3 Results of the survey(1) Kurihara city, Miyagi prefecture
According to the Kurihara city
office, Miyagi where seismic intensity 7
was recorded, post-earthquake quick
inspection of damaged buildings was
conducted for 590 wood houses(excluding warehouses) in greatly
damaged areas: Wakayanagi-Kawakita(139), Wakayanagi-Kawaminami (246),
Wakayanagi-Fukuoka (80), Semine(187), Kurikoma-Sakurada (70) at thetime of March 15. Location of theseplaces is shown in Fig. 6.2-2. Unsafe
wood houses in danger, wood houses
with limited entry and inspected woodhouses accounted for 18%, 29% and
54% of the total, respectively. The
number of collapsed houses was only
one, and the number of completely

みちのく伝創館
Mitinoku-Densokan（JMASeismograph
地震計：震度 66-)
弱）
(JMA
×

Kurikoma
栗駒桜田-sakurada

Wakayanagi
若柳
福岡fukuoka

Wakayanagi
若柳
Kawaminami
川南
Wakayanagi
Kawakita

Kurihra
City office
栗原市役所
×
×
K-NET
K-NET
築館
（計測震度
6.6）
Tsukidate(6.6)

Semine branch office
栗原市瀬峰支所(JMA（JMASeismograph
地震計：震度 66-)弱）

瀬峰
Semine×©2011 Google - 地図データ©2011 ZENRIN

Fig.6.2-2 Surveyed areas in Kurihara city-44-

destroyed houses and almost-destroyed houses were 42. The ground conditions inWakayanagi and KurikomaSakurada were poor, and most of the houses in the north andsouth side of Wakayanagi, KurikomaSakurada and Semine had age of about 30 to 40
years. On the other hand, since the ground conditions are good near the city office,structural damage was not observed in the city office.
K-NET Kurihara Tsukidate (MYG004：Instrumental seismic intensity 6.6) is set
up on the hillock 3m higher (by eye measurement) than south of parking lot of Kurihara
lyceum. There was a possibility of the amplification of earthquake motions (Photo
6.2-1). In Wakayanagi district, the ground was bad and sand boil due to liquefaction wasobserved (Photo 6.2-2). Damage to houses caused by ground transformation (Photo
6.2-3) and damage to houses with store were also observed (Photo 6.2-4).
A large residual deformation was observed in the longitudinal direction in thelarge-scale wood building used as a movie theatre then renovated to a factory (Photos
6.2-5, 6.2-6)
According to the observation of overturning of tombstone in three places inWakayanagi district, the ratio of overturning was from 10% to 40%, and it seemed that
there were a lot of overturnings in north to south direction (Photo 6.2-7).
In Kurikomasakurada district, the collapse of work hut, the drop of the mud
plasters of Nagaya-mon gates (Photo 6.2-8), the damage of plastered storehouses wereobserved, but the great damage in house was not observed.
The Seismograph of Kurikoma (JMA seismic intensity 6-) is set up on the parking
lot in the west of “Michinoku-Densokan（Photo 6.2-9）”. From the exterior damage
investigation, damage was not observed in “Mihcinoku-Densokan” and Kurikoma
Branch office (Glulam frame structure: Photo 6.2-10).

Photo 6.2-1 K-NET KuriharaTsukidate

Photo 6.2-2 Sand boil due to liquefaction-45-

Photo 6.2-3 Damage of houses caused byground transformation

Photo 6.2-4 Damage of houses with store

Photo 6.2-5 Large-scale wood building
renovated to a factory

Photo 6.2-6 Inside of the building shownin Photo 6.2-5

Photo 6.2-7 Overturning of tombstone

Photo 6.2-8 Drop of mud plasters ofNagaya-mon gate (Kurikomasakurada)

Photo 6.2-9 Seismograph of Kurikoma

Photo 6.2-10 Kurikoma Branch office(Glulam frame structure)-46-

(2) Osaki city, Miyagi prefecture
According to the Osaki city office, it was informed that the damage concentrated
in the neighbourhood of the city office and the northwest of JR Freight Company
Furukawa Station, as shown in Fig. 6.2-3. In the other areas, it was informed that there
was damage on building along the old main road in Furukawa-Araya, but damage onbuildings in the mountain region including Naruko district and so on, had never beenreported.
Heavy damage including the collapse of houses was confirmed on the way to thenorthwest of JR Freight Company Furukawa Station from the Osaki city office. Besides
the damage reported by the other institutions6.2-2), a largely deformed house, a damaged
house with store, a partially collapsed house, and so on were observed.
For example, warehouse with the mud walls renovated as store or gallery (Photo
6.2-11) was damaged heavily or slightly. There was the one whose roof system withroof tiles collapsed and fell down, as shown in Photo 6.2-12. In the area of thesewarehouses, there was a Japanese traditional post and beam construction house withlarge deformation (Photo 6.2-13) which was renovated as a store. In the opposite side ofthis house, there was the house with store (Photo 6.2-14) with story shear deformation
whose exterior mortar came off and wood lath under the mortar near the opening of theventilation fan was deteriorated and attacked by termites, as shown in Photo 6.2-15.
Such damage was confirmed in the other buildings. Most of these damage occurredalong a small river, except for a few case, and it was considered that the soft groundnear the river might amplify the earthquake ground motion.
Seismograph at JMA Furukawa (Photo 6.2-16) which recorded seismic intensity
6+ was located in the northeast corner of the Mikkamachi park. There were the former
school buildings aound it. One of them was not almost damaged (Photo 6.2-17), while
the other was damaged on roof tiles and exterior mortar without story drift. In addition
to them, a rare damage example (Photo 6.2-18) that only the 2nd story collapsed wasobserved. On the other hand, a wood school building (Photo 6.2-19) in the west of theOsaki city office seemed not to be damaged in the appearance. Besides these, the housewith store with large story drift in 1st story (Photo 6.2-20), those with large story drift in
2nd story (Photo 6.2-21), and 1-story wood house with large story drift caused by theland liquefaction were observed.
In the northwest of JR Freight Company Furukawa Station, a collapsed steel
frame building, an RC structure apartment house with rocking drift caused by the land
deformation, and a temple building (Photo 6.2-22) with large story deformation wereobserved.

-47-

古川荒谷
Furukawa-Araya

×

Commercial
building
集成材建築
の店舗
by
Glulam frame structure

Furukawa-Kitamachi
古川北町
Osaki city
office大崎市役所
×

Furukawa-Daimachi
古川台町
市役所南東部Southerneastof city office

Northwest
of JR Freight
JR 貨物古川駅北西側
Company Furukawa Station©2011 Google - 地図データ©2011 ZENRIN -Fig. 6.2-3 Surveyed areas in Osaki city

Photo 6.2-11 Warehouse with mud walls
damaged heavily or slightly

Photo 6.2-12 Warehouse with mud walls
whose roof system with roof tiles fell down-48-

Photo 6.2-13 Damaged Japanese traditional
house with large story deformation

Photo 6.2-14 House with store withlarge story deformation

Photo 6.2-15 Deterioration in buildingof Photo 6.2-14

Photo 6.2-16 JMA seismic station at
Furukawa (Seismic Intensity 6+)

Photo 6.2-17 School building sufferingdamage on roof tiles and exterior walls

Photo 6.2-18 School building whose
2nd story collapsed-49-

Photo 6.2-19 Seemingly slightly
damaged School building

Photo 6.2-20 House with store withlarge story deformation

Photo 6.2-21 House with store with 2ndstory drift more than that of 1st story

Photo 6.2-22 Heavily damaged temple
building(3) Misato Town, Miyagi
According to the Misato Town office, the number of damaged structure wasshown in table 6.2-2. There were a lot of damaged structures in Nakazone and Hirabariarea in this town.
Table 6.2-2 Number of damaged structures in Misato Town as of April 28
DamageFully
destroyed
Half
Residential
destroyed
Partially
destroyed
Non-residential

Kogota area

Nango area

Total

60

17

77

243

70

313

1,577

307

1,884

1,193

232

1,425

In Hirabari area, there were a lot of wood houses which tilted largely in theeast-west direction along the Eaigawa river (Photo 6.2-23). Photo 6.2.24 shows thewood house which leans to the fence. Most of the tombstones in this area fell toward in
the east-west direction (Photo 6.2-25). Photo 6.2-26 shows the tilted wood house of-50-

which two-story might be extended. In the southern side of Eaigawa river, there were
log house without damage (Photo 6.2-27), wood house which tilted largely at first story(Photo 6.2-28) and tilted shrine building (Photo 6.2-29).
In Nango area, ground deformation was observed in the branch town office(Photo 6.2-30), but there was few damaged houses. Photo 6.2-31 is the tilted woodhouse in Nango area. The structures in this area were damaged in a certain level during
the 2003 northern Miyagi prefecture earthquake. There is a possibility that damagedbuildings were retrofitted or rebuilt after the 2003 earthquake, because structures in thisarea seemed to be new.

Photo 6.2-23 Largely tilted house

Photo 6.2-24 Collapsed wood house

Photo 6.2-25 Tombstones in Hirabari

Photo 6.2-26 Tilted two-story house

Photo 6.2-27 Log house without damage

Photo 6.2-28 Largely tilted wood house-51-

Photo 6.2-29 Damaged shrine

Photo 6.2-30 Ground deformation in
Nango branch town office

Photo 6.2-31 Heavily damaged house

Photo 6.2-32 Inside of the house in
Photo 6.2-31-52-

(4) Ishinomaki city, Miyagi prefecture
Hiyorigaoka and Izumi-cho in Ishinomaki city is located on a hill (The altitudeis 56.4m) at the western side of Kyu-kitakami river, almost all of the buildings areresidence without public facilities (Photo 6.2-33). There were not heavily damaged
wood houses and a few wood houses of which roof tile damaged (Photo 6.2-34).
Tado-cho and Shimizu-cho are located at the northern side of Hiyorigaoka hill
and the area inundated by the tsunami according to the information6.2-5）of GSI (Fig.
6.2-4). There are a lot of low-rise wood houses with store which have big opening along
the street between Ishinomaki-kaido and Ishinomaki-betsukaido street. The inundation
depth estimated by the trace was 80-150cm. The inhabitant said that the fluid velocity ofthe tsunami was very slow and the inundation depth increased like flood. So it wasestimated that the damage of the buildings was caused by the earthquake motion.
At the both side of the street, there were collapsed wood house by earthquake(Photo 6.2-35) and tilted wood house with store (Photo 6.2-36). It was estimated that thewood houses with store which have less seismic elements at the first story were heavily
damaged.

Tado-cho, Shimizu-cho
JMA Ishinomaki

K-NET Ishinomaki

Hiyorigaoka,
Izumicho

Colored area: inundated area
Fig. 6.2-4 GSI Inundation area map of Ishinomaki city 6.2-5）-53-

Photo 6.2-33 Appearance of Izumicho

Photo 6.2-35 Collapsed wood house

Photo 6.2-34 Damaged roof tile inHiyorigaoka

Photo 6.2-36 Tilted wood house with store(5) Sendai city in Miyagi prefecture
According to the Tohoku Regional Bureau, Ministry of Land, Infrastructure
Transport and Tourism and Aoba ward office, Sendai city, the regions, where
post-earthquake quick inspection of damaged buildings was conducted, were
Asahigaoka 1, 2, 3, 4 chome(2, 250), Oritate 4, 5, 6 chome (470), Kaigamori 1 chome(400), Seikaen 1, 2chome (540) in Aoba-ku, and Higashikuromatsu, Kuromatsu 1
chome and 3 chome in Izumi-ku and so on. Location of those places was shown in
Fig.6.2-5.
From the results of investigations on Oritate and Seikaen where the damage of thehouses were serious, it was found that almost all of the damage of house were caused byground transformation. Moreover, ground transformation caused retaining wall collapse(Photo 6.2-37, 6.2-38), landslide and damage of houses (Photo 6.2-39). On the other
hand, there were some sloping lands in Kaigamori and Asahigaoka where, the numberof damage of retaining wall was minor, and damage of roof tile, collapse of concrete
block wall and outer wall were observed. In Komatsujima, Aoba ward, drop off themortar wall and damage of columns and biodeterioration by ants were observed in thehouse with store (Photo 6.2-40). Moreover, the house with large residual deformation on
the 1st floor was observed (Photo 6.2-41). In Mukaiyama, Taihaku ward, collapse of aJapanese-style hotel was observed because of the sudden fall of stone of hillback (Photo-54-

6.2-42, 6.2-43).
Kuromatsu
Higashi-Kuromatsu
黒松 東黒松Asahigaoka
旭ヶ丘 1
1-～4
4chome丁目
Komatsujim
小松島

Kaigamori
貝ヶ森

×
西花苑
Seikaen
折立
4～6
Oritate丁目
4,5,6chome

Tohoku regional
東北地方整備局
bureau, MLIT
Taihaku-ku
太白区×
Mukaiyama
向山©2011 Google - 地図データ©

Fig. 6.2-5 Observation points in Sendai city
( :observation completed,：not completed)

Photo 6.2-37 Damage of retaining walland houses（Oritate, Aoba ward）

Photo 6.2-38 Damage of house in Photo
6.2-37

Photo 6.2-39 Damage of house causedby the ground transformation (Oritate)

Photo 6.2-40 Drop off the mortar
wall (Komatsujima)-55-

Photo 6.2-41 House with large residual
deformation (Komatsujima)

Photo 6.2-42 Collapse of Japanese-style
hotel (Mukaiyama)

Photo 6.2-43 Hillback of the hotel(6) Sukagawa city, Fukushima prefecture
According to the Sukagawa city office, it was said that the damage of buildings
was concentrated around the city office at Hachiman-machi, Kaji-machi andMinami-machi. The post-earthquake quick inspection of damaged buildings (Table
6.2-3) was conducted only around the city office and finished by March 24.
There was a little damage on the upper timber construction of wood houses, andthe damage of several residential lands was reported in the east part of the city. A lot ofJapanese traditional warehouse with wooden structural members and mud walls werebuilt and left at present because Sukagawa city prospered as a merchant town. A lot of
warehouses with mud wall and stone built about 30 years ago suffered heavy damage. .
A lot of damaged wood houses were observed around the collapsed RC structurebuilding. Examples are as follows: the failed exterior mortar wall of the 2nd floor in ahouse with store (Photo 6.2-44), deterioration and damage by Reticulitermes on a partof structural member and wood lath of exterior mortar wall (Photo 6.2-45), a woodhouse whose stair hall was removed and collapsed (Photo 6.2-46), and so on.
The wood warehouses with mud wall were heavily damaged near the hotel withthe window glass broken. For example, the warehouses which deformed much (Photo
6.2-47) and whose roof system collapsed (Photo 6.2-48) were observed. A few woodhouses with roof tiles damaged (e.g. Photo 6.2-49) were found. On the other hand, roof
tiles of temple gate (called as “Sanmon”) was damaged, while the main hall of the-56-temple was not so damaged (Photo 6.2-50 and 51). The sand eruptions caused by thesoil liquefaction and the damage on the roof tiles were seen here and there in
Minami-machi, Sukagawa city. In addition, on the web site of the city, the collapsed
house was reported (Photo 6.2-52, From the city website).
Another collapsed building with uncertain structural type was found (Photo
6.2-53). According to the damage overview seen from the east of Minami-machi (Photo
6.2-54), it was observed that the wood houses with roof covered temporarily with blue
vinyl sheet which was guessed to be damaged to roof tiles were many relatively.
Table 6.2-3 Results of Post-earthquake quick inspection of damaged buildings
at Sukagawa city as of March 24
Structural type

Checked number

UnsafeLimited Entry

Inspected

Timber

1,023

245

315

463

Steel

188

51

44

93

Reinforced concrete

73

25

16

32

Total

1,284

321

375

588

Ratio

100 %

25.0 %

29.2 %

45.8 %

Photo 6.2-44 Fallen mortar of wall
(Wood house with store)

Photo 6.2-46 Collapsed stair hall

Photo 6.2-45 Deterioration and damage
due to termite on column and wood lathof exterior mortar

Photo 6.2-47 Failed warehouse with mud
wall

-57-

Photo 6.2-48 Fallen roof of warehousewith mud wall

Photo 6.2-49 Damage on roof tile

Photo 6.2-50 Minor damage of temple
gate

Photo 6.2-51 No damage on main hallof temple

Photo 6.2-52 Collapsed wood houseat Minami-machi (From Sukagawa
city website)

Photo 6.2-53 Collapsed building(Unknown structure type)

Photo 6.2-54 Damage overview from the east of Minami-machi(Many roofs covered with blue vinyl sheet)-58-

(7) Nasu Town, Tochigi prefecture
According to the Nasu Town office, the post-earthquake quick inspection ofdamaged buildings had not been carried out. The primary damage survey was conducted
only by the town officials. With the survey, 32 wood houses were found totallycollapsed.
It was said that the damage on buildings was concentrated in the area of
Nishi-Ohkubo near the town office. But, it was said that there was not collapsed woodhouse. It was said that there was little damage in Nasu-kogen highland area in thewest of national road route 4. On the other hand, it was said that damage on woodhouses were many in Toyohara-Otsu area where many cottages built on slope lands.
The damaged houses were in the area of Shio-akutsu, Chausu, Hoshibata,
Akiyamasawa, Nigashimuro, Yanome, Higashi-Iwasaki, Numanoi, Hongo, Nishizaka,
Ishizumi, Muronoi etc. and most of them were developed as residential lands. The
locations of these areas are shown in Fig. 6.2-6.
The stone-built warehouse was heavily damaged near the town office (Photo
6.2-55). The exterior stonewall of the former post office was failed (Photo 6.2-56).
Toyohara-Otsu area is in the north of Nasu Town, and cottages are built along thepath on slightly elevated hills. The movement and collapse of the wood deck (Photo
6.2-57) and collapse of the stone exterior were often observed. The several damages onwood houses caused by the slope land or the embankment were observed. The damageon the wood house due to large ground deformation caused by the earthquake motion
was also found (Photo 6.2-58). It was confirmed that the metal fasteners were installedin the column end joint and the brace end joint of this house. (Photo 6.2-59). Besides thestory drift, the crack of concrete foundation (Photo 6.2-60), the crack and loss of theexterior siding board, the broken window glass, and the failed ceiling of eaves (Photo6.2-61) were observed.
In Nishi-Ohkubo area, the several wood houses whose exterior mortar wall in thest
1 floor was almost failed were found (Photo 6.2-62). And, the wood house with large
story drift (Photo 6.2-63) and the other one damaged due to deformation of theresidential land (Photo 6.2-64) were found.

Photo 6.2-55 Damage of stone-built
warehouses

Photo 6.2-56 Damage of old post office-59-

Toyohara-Otsu
豊原乙の別荘地

Chausu茶臼
Nishi-Ohkubo
西大久保
×
那須町役場

Nasu Town office塩阿久津
Shioakutsu©2011 Google - 地図データ©2011 ZENRIN -Fig. 6.2-6 Surveyed area in Nasu Town

Photo 6.2-57 Damage of wood deck in
Toyohara-Otsu, Nasu Town

Photo 6.2-58 Heavily damaged wood
house

-60-

Photo 6.2-59 Metal fastener at the endof column and brace

Photo 6.2-60 Crack of foundation

Photo 6.2-61 Failed ceiling of eave

Photo 6.2-62 Damage of exterior mortar
wall

Photo 6.2-63 Wood house with large story
story drift

Photo 6.2-64 Damaged house due todeformation of residential land(8) Yaita city, Tochigi
According to the Yaita city office, the post-earthquake quick inspection ofdamaged buildings was limited to the houses at the request of residents and all houses in
evacuation zone due to deformation of the residential land. By March 23, 108 buildings(including 3 buildings, such as stone warehouse, which couldn’t be evaluated) weresurveyed by the post-earthquake quick inspection of damaged buildings. The numbersof “Unsafe”, “Limited Entry” and “Inspected” were 40, 42 and 23, respectively.
Evacuation was announced officially to the east of Lobin-city due to thedeformation of the residential land. It was said that many damage were observed in the-61-northeast area of Narita-Happy-Highland, Arai, Hariu, and Koshiwata wheredevelopment was made by sharpening slope lands and filling up swamps. The locationsof the above areas are shown in Fig. 6.2-7.
In Lobin-city (Photo 6.2-65), the cracks of fence and retaining wall, the caving ofroad bed, the ups and downs of the residential land (Photo 6.2-66) and the crack of thefoundation concrete (Photo 6.2-67) were often observed. In addition, damage on theroof tile, especially top of the roof, and collapsed concrete block fences were observed.
Narita-Happy-Highland at the north of Lobin-city was a developed residential
land. Most of the damage on buildings was due to the deformation of the residential
land. A wood house with 1/10 radian shear deformation (Photo 6.2-68) was found.

荒井
Arai

Hariu
針生

Narita Happy Highland
ハッピーハイランド
ロビンシティー

Lobin city

×

矢板市役所
Yaita
city office©2011 Google - 地図データ©2011 ZENRIN -Fig. 6.2-7 Research area in Yaita city

Photo 6.2-65 No damaged houses at
Lobin-city area

Photo 6.2-66 Ups and downs ofresidential land-62-

Photo 6.2-67 Crack of foundation

Photo 6.2-68 Wood house with large shear
deformation(9) Hitachiohta city, Ibaraki prefecture
According to the post-earthquake quick inspection of damaged buildings, thenumber of “Unsafe” was 199, “Limited Entry” was 549 and “Inspected” was 574 in thecity. The number of “Unsafe” was 87, “Limited entry” was 235 and “Inspected” was 97
in the Matsuzaka-cho. There are a lot of damaged buildings at the Kanasago area
(Matsuzaka-cho and Nakano) in the Kujigawa river basin. Hitachiohta city office had
made the hazard map that considers the subduction-zone earthquake. The seismic
intensity is from 5+ to 6- at the Kujigawa river basin area.
There were a lot of damaged fence made by the Ohyaishi stone. A collapsed farm
type house was observed (Photo 6.2-69, 6.2-70). The mortar plastered wall finish of thewood house at the land filled paddy field fell down (Photo 6.2-71).

Photo 6.2-69 Collapsed wood house

Photo 6.2-70 Breakage of entrance part.

Photo 6.2-71 Falling down of mortar
plastered wall-63-

(10) Naka city, Ibaraki prefecture
Naka city is surrounded by the Nakagawa river and the Kujigawa river and thecenter of the city is located on the plateau. A lot of damaged buildings were located at
the Kujigawa river basin. The number of totally collapsed houses were 4 at
Kadobe-shimogawara, 1 at Motoyonezaki as of March 25. By the post-earthquake quick
inspection of damaged buildings, the number of “Unsafe” was 88. The damage
information was reported at Kadobeakutsu and Urizura.
At Kadobeshimogawara in Naka city, there were a lot of collapsed barns (Photo
6.2-72) and heavily damaged nagayamon gates (Photo 6.2-73). A damaged house withstore was observed (Photo 6.2-74). A lot of collapsed barns were observed at
Kadobeakutsu.
A two story wood house with mortar finish collapsed at the urban area of Urizura
in Naka city (Photo 6.2-75).
At the wood gymnasium (Photo 6.2-76, Photo 6.2-77) with curved glue laminatedtimber built in 1985-1989 in Urizura, buckling and tensile failure of the steel braces, thebreakages of the foundation concrete at the brace joint were observed (Photo 6.2-78). At
the wood school building (Photo 6.2-79), the slip of wood braces (Photo 6.2-80), thedeformation of steel roof plate, wood flooring and interior material due to the contact
with the stairway made by reinforced concrete were observed.

Photo 6.2-72 Collapsed nagayamon gate
(Kadobe)Photo 6.2-73 Tilted nagayamon gate
(Kadobe)Photo 6.2-74 Damaged house with store(Kadobe)Photo 6.2-75 Collapsed house(Urizura)-64-

Photo 6.2-76 Wood gymnasium

Photo 6.2-77 Inside of the gymnasium

Photo 6.2-78 Breakage of thefoundation concrete

Photo 6.2-79 Wood school building

Photo 6.2-80 Slip of the wood brace(11) Mito city, Ibaraki prefecture
According to the Mito city office, the number of totally collapsed building was
34 (residential 2, non-residential 32), half destroyed building, 66 (residential 34,
non-residential 32) as of March 25.
The damaged buildings were mainly located around the city hall and inMotomachi, Yoshinuma-cho, Aoyagi-cho, Yanagawa-cho, Kamikochi-cho, Taya-cho,
Joto and Sannomaru. The number of the collapsed residential house is two at
Motomachi.
In the southern part of the Mito railway station, the ground settlement occurred-65-

and the gap between the high-rise building and ground was observed. This area had
been part of the Senbako lake and was developed to residential land in 1965-1974. The
ground settlement was also observed at the city hall and the entry to the building wasrestricted.
There was a heavily damaged Nagayamon gate at Yoshinuma-cho (Photo
6.2-81). The damaged barns were observed at Aoyagi-cho, Yanagawa-cho, Taya-cho(Photo 6.2-82).

Photo 6.2-81 Heavily damaged
Nagayamon gate (Yoshinuma-cho)

Photo 6.2-82 Damaged barn
(Aoyagi-cho)(12) Joso city, Ibaraki prefecture
According to the Joso city office, Ibaraki prefecture, structural damage was notobserved for houses. An announcement of collapsed house immediately after theearthquake, is thought to be the damage to a wood hut in a resting place. The house built
in the side of Lake of crescent was inclined because of the soil liquefaction (Photo
6.2-83, 6.2-84). Although there were several inclined houses because of the soilliquefaction, a lot of damage to the roof tile were observed, and it seemed that the ratioof the damage of the roof tile was comparatively high.

Photo 6.2-83 Damage of resting place(Joja-machi, offered by Joso city office)Photo 6.2-84 Damage of ground near the
resting place（offered by Joso city office）-66-

(13) Ryugasaki city, Ibaraki prefecture
According to the Ryugasaki city office, Ibaraki prefecture, structural damage was
not observed in houses, and information about collapsed house immediately after theearthquake, was thought to be the damage of barn in the Takasu-cho. The
post-earthquake quick inspection of damaged buildings was conducted for 58 woodhouses based on the request from the citizens. According to the department, unsafe
wood houses in danger and wood houses with limited entry accounted for 12, and 29
respectively. Most of the damage of houses were damage of roof tile and outside wall.
There were no damage due to inclination of structural building frame. Though 6 houses
and 1 barn are judged as partial collapse, the sites of those buildings were not located inconcentrated specific region. The surrounding of the city office and JR Sanuki station
are old urban areas, grounds of those areas were low and weak, and have a lot ofdamage of the roadbed. On the other hand, two new towns in the east and the west areasin the city were located on the hill, the ground is sound, and the damage of houses was
not reported. Sand eruption by soil liquefaction was partly observed in the Takasu-cho
area.
6.2.4 Conclusions
From the damage survey on the wood houses due to ground motion in Kurihara
city, Osaki city, Misato town, Ishinomaki city, Sendai city in Miyagi prefecture,
Sukagawa city in Fukushima, Nasu town, Yaita city in Tochigi prefecture, andHitachiota city, Naka city, Mito city, Joso city, Ryugasaki city in Ibaraki prefectue, thefollowings were summarized.
1) The damage on many wood houses due to ground motion was confirmed in Osaki
city in Miyagi prefecture, Sukagawa city in Fukushima prefecture, Nasu town in
Tochigi prefecture, and Hitachiota city and Naka city in Ibaraki prefecture.
2) Although the seismic intensity 7 was recorded in Kurihara city, Miyagi prefecture, it
was observed that the damage on wood houses was minor.
3) The heavy damage on wood houses caused by the failures of residential land wasconfirmed in Sendai city, Miyagi prefecture, and Yaita city, Tochigi prefecture. The
number of wood houses suffering such damage was quite large.
4) The damage of the roof tile in Fukushima and Ibaraki prefectures seemed muchlarger than that in Miyagi prefecture where large earthquakes occurred frequently.
5) The possibility that the ground motion was amplified on the land filled up fromswampland or rice field, even if the residential land did not fail, was suggested in
Kurihara city, Osaki city in Miyagi prefecture, Nasu town in Tochigi prefecture,
Hitachiota city, Naka city, Joso city, Ryugasaki city in Ibaraki prefecture, and so on.
6) In Osaki city, several rare damage examples that residual story deformation of 2nd-67-

floor was larger than that of 1st floor were confirmed.
The selected houses will be surveyed in detail and each damage cause will be
discussed in future, based on the results of the damage summary of theabove-mentioned wood houses.
References
6.2-1) Masato MOTOSAKA：The 2011 Off The Pacific Coast of Tohoku Earthquake Quick Report of The Damage Survey http://japonism.org/wp-content/uploads/2011/04/motosaka-report.pdf
6.2-2) Naohito KAWAI：Quick Report of Damage Survey on Buildings Due to The
2011 Off The Pacific Coast of Tohoku Earthquake by Kogakuin University
Survey Team for Wood Buildings, Quick Report of Damage Summary Survey inOsaki City and Ichinoseki City on April 11. (An article on the way),
non-publication document.
6.2-3) The Japan Wood Research Society: (non-publication document)
6.2-4) NILIM and BRI：Quick Report of The Field Survey and Research on “The 2011
Off The Pacific Coast of Tohoku Earthquake”
http://www.nilim.go.jp/lab/bbg/saigai/h15miyagi/chousa.pdf
6.2-5) Geographical Survey Institute: Figure of inundation range general condition
http://www.gsi.go.jp/common/000059847.pdf

-68-

6.3
6.3.1

Damage to Reinforced Concrete Buildings
Introduction

The 2011 Tohoku earthquake caused a lot of damage to buildings in a wide area of
Tohoku and Kanto regions of Japan. The Joint Survey Team investigated the damage toreinforced concrete (RC) buildings and reinforced concrete buildings with embedded
steel frames (referred to as steel reinforced concrete, or SRC) in the affected areas
where seismic intensities were classified as 6 lower (6-) and over by the Japan
Meteorological Agency (JMA) in Iwate, Miyagi, Fukushima and Ibaraki. The objectiveof the field investigation was to see the picture of the overall damage to the buildings
and to classify their damage patterns. The survey was conducted several times fromMarch 14 to the middle of May in the districts as shown in Fig. 6.3-1. This reportpresents the outline of the field investigation.

Tono

Aoba, Wakabayashi,
Miyagino ward,
Sendai
The 2011 off the
Pacific coast of
Tohoku EQ

Fukushima

Nihonmatsu

Shirakawa

Koriyama
Sukagawa
HitachiKasama

Hitachiomiya

HokotaFig. 6.3-1 Investigated Area (free mapping program, ‘KenMap’ was used)
6.3.2

Characteristics of damage on RC buildings

In the 2011 Tohoku earthquake, strong earthquake motions were recorded invarious locations of the Tohoku and the Kanto regions and caused various patterns ofdamage in a wide area. At the same time, the damage concentrated on specific areas was-69-not seen generally. As a rule, it would appear that structural damage with buildings was
not particularly heavy in comparison with the measured JMA seismic intensities.
Consequently, there is not a significant difference in damage situations among thelocations. However, the damage to structural members was somewhat concentrated onlimited areas, such as Wakabayashi ward in Sendai city and Sukagawa city. It is known
that these areas were formed on paddy fields or moats. Therefore, it can be wellestimated that ground conditions in the areas possibly contributed to the damage.
The patterns of structural damage on RC buildings identified by the field surveys
are almost the same with those that had been observed in past earthquake damage
investigations. Some serious types of damage were observed, such as story collapse of
low-rise buildings, collapse of soft-first story (pilotis), and the loss of vertical load
carrying capacity of columns due to shear failure. Most of severely damaged buildings
were designed with the previous seismic design code that was enforced before June
1981. Some SRC buildings designed under the current seismic design code enforced
after June 1981, caused damage of buckling of their longitudinal reinforcements nearbase plates at the bottom of column. The same damage is known to have occurred also
in the Hyogoken Nambu Earthquake in 1995 (Kobe Earthquake). In addition, buildings
designed under the current seismic design code were confirmed to have no collapse but
some damage like shear cracks at their beam-column joints or horizontal cracks at theirconcrete placing joints. The patterns of the damage of RC and SRC buildings that wereobserved through the site investigation are classified into those for structural andnonstructural elements in the following.
A) Damage of structural elementsA-1) Collapse of first storyA-2) Mid-story collapseA-3) Shear failure of columnsA-4) Flexural failure at the bottom of column and base of boundary columns on
multi-story shear wallsA-5) Pullout of anchor bolts and buckling of longitudinal reinforcements at exposedcolumn base of steel reinforced concrete (SRC) buildingsA-6) Shear failure or bond splitting failure of link beam of multi-story coupledshear wallsA-7) Building tiltingA-8) Destruction, failure or tilting of penthousesA-9) Damage of seismic retrofitted buildingsB) Damage of nonstructural elementsB-1) Flexural failure at the bottom of column with wing wallB-2) Damage of nonstructural wall in residential buildingB-3) Damage and falling of cladding-70-B-4) Tilting or dropout of components projecting on the roofB-5) Collapse of concrete block wall and stone masonry wall
6.3.3 Damage of Structural ElementsA-1) Collapse of first story
The first story in a two-story RC office building shown in Photo 6.3-1 wascompletely collapsed in Wakabayashi ward, Sendai city. In addition, the shear failure
and the axial deformation of the columns on the second floor of this building caused thebuckling of the longitudinal reinforcements and the fracture of the hoops of columns in
the first story.

Photo 6.3-1 First-story collapsed building (Wakabayashi ward, Sendai city)
The soft-first story collapse occurred on the four-story RC residential building witha shop in the first floor in Koriyama city, and is attributed to the shear failure of thecolumns on the first story and the torsional deformation (Photos 6.3-2 and 6.3-3). The
RC shear wall on the first story was collapsed out-of-plane with buckling of reinforcing
bars.

Photo 6.3-2 First-story collapsed building(Koriyama city)

Photo 6.3-3 Close-up view of the fallen
story

-71-

The three-story RC building shown in Photo 6.3-4 was severely damaged on thefirst story, which was located at the intersection in Sukagawa city, had a few walls on
the facade on the first story and many walls on the back of the first story and the second
story and higher. The corner columns faced to the intersection were significantly
destroyed as shown in Photo 6.3-5. The loss of axial load carrying capacity of thefirst-story columns caused the drop of the second and higher stories.

Photo 6.3-4 First-story collapsed building(Sukagawa city)

Photo 6.3-5 Close-up view of the fallen
storyA-2) Mid-story collapse
The three-story office building shown in Photo 6.3-6 in Wakabayashi ward, Sendai
city partially collapsed on the second story and the building tilted. Only the second
story has openings on the wall at the gable side, as shown in the left of Photo 6.3-6. For
this reason, it was assumed that the openings were intensively deformed and resulted inshear failure of the short columns formed by the hanging and spandrel walls. The shear
failure of the long columns on the third story was observed possibly due to the effect of
the collapse of the second story. The damage to the columns and beams on the first story
was not seen, while shear cracks were observed on the nonstructural walls.

Photo 6.3-6 Mid-story collapsed building (Wakabayashi ward, Sendai city)
Photo 6.3-7 shows the three-story RC school building, which was constructed in-72-

1966 and has a Y-letter shape plan in Fukushima city. The mid-story collapse occurredon the second story, and the part of the third story was heavily damaged. In addition, theshear failure also occurred on the columns in the first story, as shown in Photo 6.3-8.
Visual damage was not seen in other school buildings and the gymnasium on the samesite. The seismic indices of the structure, IS on the first and second stories of thebuilding were below the seismic demand index of structure, IS0 by the seismic
evaluation method 6.3-1), therefore the seismic retrofit of the building was being planned.

Photo 6.3-7 Mid-story collapsed building(Fukushima city)

Photo 6.3-8 Shear failure of thefirst-story columnA-3) Shear failure of columns
The three-story RC building constructed in 1963 was suffered from the shear
failures of columns in Tono city, where the JMA seismic intensity was 5 upper (5+)(Photo 6.3-9). Two extremely short columns on the first-story, four columns on thenorthern plane of structure and an interior shear wall were failed in shear as shown in
Photo 6.3-10, and short columns with spandrel wall, some long columns on the southernplane of structure had shear cracks. The post-earthquake damage evaluation 6.3-2) was
conducted for the building in the longitudinal direction. In the result, the building wasdetermined to represent heavy damage (residual seismic performance ratio, R=57.8%).
The building had been damaged in the South Sanriku Earthquake in 2003 (JMA seismic
intensity 6 lower). For this reason, cover concrete was then recast on the shear-cracked
columns, and the existing columns were temporary strengthened with H-shaped steel, as
shown in Photo 6.3-11. However, the 2011 Tohoku earthquake affected these columns
again.

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Photo 6.3-9 Appearance of the damaged building (Tono city)

Photo 6.3-10 Shear crack on shear wall

Photo 6.3-11 Column strengthened with
H-shaped steel

The next case is that the shear failure occurred on the first-story columns in the
two-story RC building in Aoba ward, Sendai city (Photos 6.3-12 and 6.3-13). Somecolumns of the building were intact after the mainshock on March 11, but aftershocks
caused shear failure to some of them, as shown on the right of Photo 6.3-13. It was
confirmed that the aftershocks accelerated the damage level of this building.

Photo 6.3-12 Appearance of the damaged building (Aoba ward, Sendai city)-74-caused by aftershocks

Photo 6.3-13 Shear cracks of first-story columns
Photo 6.3-14 shows the four-story RC building that was constructed in 1970 in
Sukagawa city. The columns with the spandrel wall on the first story were heavily
damaged in shear and shorten in the axial direction as shown in Photo 6.3-15. The samedamage was seen on the second-story exterior columns. Some of the reinforcing bars ofthe damaged columns that were raised from the foundation are anchored with a
180-degree hook near the mid height of story. It is considered that the shear failure
began at the point. Two shear walls were severely damaged, which are arranged in thecenter core of the building to resist mainly horizontal forces. In particular, thesecond-story core wall was failed in shear in both of the span and longitudinal
directions, and the longitudinal reinforcements in the boundary column of shear wall
were heavily buckled as shown in Photo 6.3-16.

Photo 6.3-14 Appearance of damaged building (Sukagawa city)-75-

Photo 6.3-15 Shear failure of shortcolumnPhoto 6.3-16 Failure of shear wall

The three-story RC building constructed in 1964 on a hill in Kasama city shown in
Photo 6.3-17 suffered also damage. Cracks in the ground were observed around thebuilding. As seen in the photo, the RC structure on the first story was severely damaged.
Shear failure occurred on many exterior columns, which were made shorter in clear
height by the hanging and spandrel walls without structural slit, as shown in Photo
6.3-18. In addition, the failures of the shear walls with openings were observed (Photo
6.3-19).

Photo 6.3-17 Appearance of damaged building (Kasama city)-76-

Photo 6.3-18 Shear failure of column

Photo 6.3-19 Shear failure of wall with
openingA-4) Flexural failure at the bottom of column and base of boundary columns on
multi-story shear walls
The building that consists of nine-story SRC and two-story RC structures in Aoba
ward, Sendai city suffered from the earthquake (Photo 6.3-20). In the high-rise building,the multi-story shear wall of the gable side was subject to flexural failure at the third
floor. Crushing of concrete and buckling of the longitudinal reinforcements wasobserved at the bottom of the boundary column of shear wall, as shown in Photo 6.3-21.
This building was also damaged by the Miyagiken-oki Earthquake in 1978 and had been
retrofitted.

Photo 6.3-20 Appearance of damagedbuilding (Aoba ward, Sendai city)

Photo 6.3-21 Crushing at the bottom ofcolumn of the multi-story shear wall-77-A-5) Pullout of anchor bolts and buckling of longitudinal reinforcements at
exposed column base of steel reinforced concrete (SRC) buildings
Photo 6.3-22 shows the appearance of a damaged building, which is the nine-story
SRC residential building constructed in 1991 in Koriyama city. Pullout of anchor bolts,
buckling of reinforcing bars and compressive failure of concrete occurred at the cornercolumn and the bottom of multi-story shear wall in the first story, as shown in Photo
6.3-23, and shear cracks and bond splitting cracks were observed on the first story
columns.

Photo 6.3-22 Appearance of damagedbuilding (Koriyama city)

Photo 6.3-23 Damage at the bottom of
SRC column

The damage at the bottom of SRC column and shear wall was also observed on thebuilding in Shirakawa city shown in Photos 6.3-24 and 6.3-25, which was composed of
RC and SRC structures. Pullout of anchor bolts of the exposed-type column baseoccurred. In consequence, the reinforcing bars were forced to stretch large and thebuckling of them occurred around the base plate, as shown in Photo 6.3-26.

Photo 6.3-24 Appearance of damaged building (Shirakawa city)-78-

Photo 6.3-25 Damage of the bottom of
SRC column and shear wall

Photo 6.3-26 Close-up view of thebottom of SRC column

This type of damage was observed not only in buildings designed under theprevious seismic design code but also in some buildings constructed under the current
seismic design code.
A-6) Shear failure or bond splitting failure of link beam of multi-story coupledshear walls
The shear failure or bond splitting failure occurred on the link beam connecting
coupled shear walls from low-rise to high-rise stories on the eight-story RC building in
Aoba ward, Sendai city, as shown in Photo 6.3-27. The link beams have two openings at
the center of them, and were damaged around these parts (Photo 6.3-28).

Photo 6.3-27 Appearance of damagedbuilding (Aoba ward, Sendai city)

Photo 6.3-28 Damage of boundary beamwith opening-79-A-7) Building tilting
The fourteen-story RC building shown in Photo 6.3-29 was settled down and wastilted about 1/70 radian, which was one of two residential buildings located in L-shapewith expansion joint in Miyagino ward, Sendai city. The shear cracks on the
nonstructural walls over every story and some parts of mullions occurred in bothbuildings as shown in Photos 6.3-30 and 6.3-31, which damage was classified as B-2.
Though the other building without inclination had same shear cracks on the
nonstructural walls from first to sixth story in the Miyagiken-oki Earthquake in 1978and had been repaired with concrete replacement, almost same damage was happenedon the similar part.

Photo 6.3-29 Appearance of tilted building (Miyagino ward, Sendai city)

Photo 6.3-30 Shear cracks on
nonstructural wall

Photo 6.3-31 Shear cracks on mullion

Photo 6.3-32 shows a residential building that sank and leaned in the longitudinal
direction in Shirakawa city. The balcony, of which height above ground level was about
77cm, went down to ground surface in the gable side, as shown in Photo 6.3-33.

-80-Significant settling was also observed on a sidewalk in surrounding area.

Photo 6.3-32 Appearance of sunken andleaned building (Shirakawa city)

Photo 6.3-33 Sunken balconyA-8) Destruction, failure or tilting of penthouses
The damage on penthouses was observed everywhere, like tilting of it in Aoba
ward, Sendai city, as shown in Photo 6.3-34. The clock tower attached to the five-story
RC building constructed in 1954 was destroyed at the bottom of it, despite the building
was hardly damaged in Fukushima city (Photos 6.3-35 and 6.3-36).

Photo 6.3-34 Damaged penthouse (Aoba ward, Sendai city)-81-

Photo 6.3-35 Damaged clock tower(Fukushima city)

Photo 6.3-36 Bottom of the towerA-9) Damage of seismic retrofitted buildings
Photo 6.3-37 shows the two-story RC office building constructed in 1969 in
Hitachiomiya city. The building has been retrofitted with framed steel braces in thelongitudinal direction in 2003, because the seismic index of structure, IS on the firststory of the building was below the seismic demand index of structure, IS0 by theseismic evaluation method 6.3-1). Meanwhile, the building in the span direction was not
retrofitted, as a consequence of that the seismic index of structure in the direction
satisfied the seismic demand index of structure. The steel braces are eccentricallyinstalled to the center axis of the beams and columns.
Shear cracks occurred on the columns with the framed steel braces at the 2011
Tohoku earthquake as shown in Photo 6.3-38, although the remarkable damage such as
yield of steel was not seen on the braces. Flexural cracks at the beam ends of thesecond-story in the span direction and shear cracks at the beam ends of the third-story
were observed, respectively. A maximum deflection of 128mm was happened at thecenter in the span direction with a span of 12m. It would appear that the deflection wasincreased due to the damage occurred on the beam end by the earthquake, thought theundersurface of the beam has been strengthened. Because the beam had cracks causedby the past earthquake, it was reinforced with steel plates in the range of quarter beam
length from the column.

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Photo 6.3-37 Appearance of damagedbuilding (Hitachiomiya city)

Photo 6.3-38 Shear crack on column
with framed steel braces

There were many seismic retrofitted buildings including school buildings in theaffected areas where the strong earthquake motions were observed. Based on the resultsof the investigation, these retrofitted buildings were hardly damaged or slightly harmed,
it means that the seismic strengthening on existing buildings act effectively against theearthquake.
6.3.4

Damage to nonstructural elementsB-1) Flexural failure at the bottom of column with wing wall
The separation of cover concrete at the bottom of wing wall was observed on thefive-story RC building constructed in 2007 in Sukagawa city, as shown in Photos 6.3-39
and 6.3-40. In this report, that case is classified as the damage of nonstructural elements,
because the wing wall is generally designed as the nonstructural element, which is notexpected to resist the external force.

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Photo 6.3-39 Appearance of damagedbuilding (Sukagawa city)

Photo 6.3-40 Separation of concreteof wing wallB-2) Damage of nonstructural wall in residential building
The nonstructural walls around the front doors from lower to top floors were
subject to shear failure, while the doors were deformed on the ten-story SRC residentialbuilding constructed in Aoba ward, Sendai city in 1996, as shown in Photos 6.3-41 and6.3-42. In addition, shear cracks were observed on the mullion walls on balconies insome of the lower floors.

Photo 6.3-41 Appearance of damagedbuilding (Aoba ward, Sendai city)

Photo 6.3-42 Shear failure of
nonstructural wall

In the nine-story SRC residential building shown in Photo 6.3-22 in Koriyama city,
damage of the nonstructural elements was seen (Photo 6.3-43). In addition, large shear-84-cracks occurred on the nonstructural wall in the longitudinal direction. For this reason,
the front door was deformed out-of-plane as shown in Photo 6.3-44, and could not be
opened and closed. The shear cracks on the mullion walls also occurred in theeight-story RC hotel building in Sukagawa city (Photos 6.3-45 and 6.3-46).
The cases where shear cracks occurred on the nonstructural walls around the front
door or on the mullion wall of the balcony were relatively often observed in urban
residential buildings, regardless of the seismic design codes applied to.

Photo 6.3-43 Damage of nonstructural wallin same building shown in Photo 6.3-22

Photo 6.3-45 Appearance of damagedbuilding (Sukagawa city)

Photo 6.3-44 Damage ofnonstructural wall and deformed doorin same building shown in Photo
6.3-22

Photo 6.3-46 Shear crack on nonstructuralwallB-3) Damage and falling of cladding
Photos 6.3-47 and 6.3-48 show the case where the AAC (Autoclaved lightweight
Aerated Concrete, the abbreviated term ‘ALC’ is commonly used in Japan, instead.)-85-

panel on the upper floor in the eight-story building fell away, and Photo 6.3-49 is thecase where the tile on exterior wall was dropped, in Aoba ward, Sendai city.
These kinds of damage relatively often occurred on buildings without structural
damage, not limited to specific areas. Despite of the construction period and the seismic
design codes applied to, these damage are often seen on many buildings.

Photo 6.3-47 Damaged building with
AAC panels (Aoba ward, Sendai city)

Photo 6.3-48 Dropped AAC panels

Photo 6.3-49 Damage of tile on exterior wallB-5) Collapse of concrete block wall and stone masonry wall
The collapse of concrete block wall and stone masonry wall are well known asearthquake damage caused by strong seismic motion. The damage of that type was often
observed in the field investigation, as shown from Photo 6.3-50 to Photo 6.3-53.

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Photo 6.3-50 Collapse of concrete blockwall (Koriyama city)

Photo 6.3-51 Collapse of concrete blockwall (Sukagawa city)

Photo 6.3-52 Collapse of stone masonrywall (Fukushima city)

Photo 6.3-53 Collapse of stone masonrywall (Shirakawa city)

6.3.5 Concluding Remarks
In this report, the patterns of damage of reinforced concrete (RC) and steel
reinforced concrete (SRC) buildings caused by earthquake motions under the 2011
Tohoku earthquake were classified as the damage on structural and nonstructuralelements and the examples of them were described. As previously stated, almost all of
the patterns of damage were observed in past destructive earthquakes such as the
Hyogoken Nambu Earthquake (Kobe Earthquake) in 1995 and the Mid Niigata
Prefecture Earthquake in 2004. However, the following patterns of structural damage
that were observed in the Hyogoken Nambu Earthquake have not been confirmed
within the scope of the investigation conducted so far.
- Story collapse of soft-first story building designed under the current seismic
design code
- Mid-story collapse in mid-rise and high-rise buildings- Overturning of buildings

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-

Failure of beam-column joint in building designed under the current seismic
design code
Fracture of pressure welding of reinforcements
Falling of pre-cast roof in gymnasium

In general, there are only a few cases of serious structural damage that was causedby the earthquake motions. On the contrary, it was the remarkable cases caused by theearthquake that public buildings like city hall under the past seismic design code
suffered from severer damage and could not be continuously used. The main cause of
the damage on these buildings was the loss of the vertical load carrying capacity due toshear failure of short columns. The fact makes us reconfirm that seismic retrofit of thesepublic buildings is particularly important, which must be operated as the disastermanagement facilities.

References
6.3-1) The Japan Building Disaster Prevention Association: Standard for Seismic
Evaluation of Existing Reinforced Concrete Buildings, 2001 (English Version
in 2005)
6.3-2) The Japan Building Disaster Prevention Association: Guideline for
Post-earthquake Damage Evaluation and Rehabilitation, 1991 (revised in 2001).
(in Japanese)-88-6.4 Damage to Steel Gymnasiums
6.4.1 Introduction
The damage to general steel buildings such as offices and shops caused by the 2011
Tohoku earthquake in the areas of Ibaraki, Fukushima and Miyagi prefectures with JMA
seismic intensity around 6 was investigated for two weeks after the earthquake. Structuresof steel buildings are generally covered with exterior cladding and interior finishing. For
this reason, the real situations of the damage to columns, beams and braces may not becorrectly determined under the visual damage observation. Therefore, the damage
investigation on steel gymnasiums whose structural members are generally exposed wasconsidered and conducted. The damage investigation for such steel gymnasiums was
carried out in the areas of Ibaraki prefecture with JMA seismic intensity around 6. Thissection describes the outline of the damage investigation of the steel gymnasiums.
6.4.2 Outline of damage investigation of steel gymnasiums(1) Outline of damage investigation of high school gymnasiums in Ibaraki prefecture
Gymnasiums designed under the seismic code before June 1981 (hereinafterreferred to as previous seismic code) were heavily damaged in the Mid Niigata Prefecture
Earthquake in 2004, but most of gymnasiums designed under the current seismic code
were not damaged6.4-1)~6.4-3). Consequently, as the subject of the damage investigation,
steel gymnasiums constructed under the previous seismic code were mainly chosen. The
investigation covered a wide range of areas in Ibaraki prefecture where JMA seismic
intensities 5 (+) to 6 (+) were recorded (Ooarai town, Shirosato town, Hitachi city, Mito
city, Naka city, Hitachinaka city, Chikusei city, Kasama city, Hokota city, Tsuchiura city,
Bando city, Koga city, Shimotsuma city and Joso city). The main purpose of theinvestigation is to determine what damage pattern was often observed in these areas and inwhich area the pattern was often distributed. A total of 44 gymnasiums in high schools
were chosen and investigated.
(2) Outline of damage investigation of elementary and junior high school
gymnasiums in Mito city
In general, building size (total floor area) of high school gymnasiums seems to belarger than the size of elementary and junior high school gymnasiums. In order to know aneffect of building size on earthquake damage situation, damage investigation ofelementary and junior high school gymnasiums was considered and conducted. The resultof the damage investigation for the high school gymnasiums in Ibaraki prefecture showedthat the areas around Mito city suffered relatively larger structural damage than other areas.
Then, Mito city was chosen as the survey area of the damage investigation for-89-

gymnasiums in elementary and junior high school. A total of 22 gymnasiums inelementary and junior high schools constructed under the previous seismic code in Mito
city were investigated.
6.4.3 Results of damage investigation of steel gymnasiums(1) Results of high school gymnasiums in Ibaraki prefecture1) Outline of structure of investigated gymnasiums
A total of 44 gymnasiums were investigated in Ibaraki prefecture. The number ofgymnasiums constructed under the previous seismic code is 41. There are 4 two-story
gymnasiums, and 40 one-story gymnasiums. The number and percentage of structural
types of the investigated gymnasiums are shown in Table 6.4-1. In general, the structural
types of gymnasiums are classified into 3 classes as shown in Table 6.4-1, but thepercentages of the types seem to strongly depend on the regions. For example, in thedamage investigation6.4-1)~3) of the Mid Niigata Prefecture Earthquake in 2004, thepercentage of the mixed structure consists of lower RC frame and upper steel frame was
75%, and the percentage of steel moment-resisting frames was 6%. From table 6.4-1, it isfound that the percentage of the mixed structure in Ibaraki prefecture is smaller thanNiigata prefecture, and the percentage of steel moment-resisting frames is larger.
Table 6.4-1 Structural types of investigated high school gymnasiums
Mixed structure consist of lower
RC frame and upper steel frame

Steel frame structure20（45％）

15（34％）

Steel brace
frame

Steel momentresisting frame

Steel brace
frame

Steel momentresisting frame

15（34％）

5（11％）

7（16％）

8（18％）

RC frame structure
having steel roof Unidentified
frame

6（14％）

3（7％）2) Structural damage
The types of observed structural damage in this investigation include a) bucklingand fracture of brace member and fracture of its joint, b) buckling of diagonal member oflatticed column, c) damage of connection (bearing support part) between RC column andsteel roof, d) deflection, buckling and fracture of roof horizontal brace, and e) cracking ofcolumn base concrete. The a) and b) damage types are included as the type of severe
structural damage based on the damage evaluation standard of earthquake damagedbuildings6.4-4). However, the number of these severe damaged gymnasiums is 2 and 1
corresponding to the damage type a) and b), respectively. Buckling of diagonal member oflatticed column is damage to the column in span direction frames, and was not observed
under the damage investigation of the Mid Niigata Prefecture Earthquake in 20046.4-1)~6.4-3).

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From the results of this investigation, it seemed that structural damage in Mito city,
Hokota city and Naka city was relatively larger than in other areas.
3) Nonstructural damage
The types of nonstructural damage observed in this investigation include dropping of
ceilings and exterior walls and breakage of windows, etc. In four of the investigatedgymnasiums, ceiling materials were extensively dropped, which is classified into thesevere damage category based on the damage evaluation standard6.4-4). In fivegymnasiums, breakage of many windows was observed.
4) Damage situations of seismic retrofitted buildings
Seismic retrofitting was performed in five of the investigated gymnasiums. One of
the five retrofitted gymnasiums was constructed in the area where relatively severe
damage was observed. Structural and nonstructural damage of this gymnasium were notobserved.
(2) Results of elementary and junior high school gymnasiums in Mito city
1) Outline of structure of investigated gymnasiums
A total of 22 gymnasiums were investigated. 20 of the gymnasiums wereconstructed under the previous seismic code. All of the investigated gymnasiums are
one-story. The structural types of the gymnasiums are shown in Table 6.4-2, as the case of
the high school gymnasiums. The percentage of the mixed structure that consists of lower
RC frame and upper steel frame is 19%, and the percentage of RC frame structure having
steel roof frame is 41%.
Table 6.4-2 Structural types of investigated elementary and junior high school
gymnasiums
Mixed structure consist of lower
RC frame and upper steel frame

Steel frame structure4（19％）

7（32％）

Steel brace
frame

Steel momentresisting frame

Steel brace
frame

Steel momentresisting frame

3（1４％）

1（5％）

1（5％）

6（27％）

RC frame structure
having steel roof Unidentified
frame

9（41％）

2（10％）

2) Structural damage
Five types of the structural damage, shown in the result of the investigation ofhigh-school gymnasiums, were also observed in the elementary and junior high school
gymnasiums. However, the degree of structural damage in the elementary and junior highschool gymnasiums seems to be smaller than in the case of high school gymnasiums.

-91-3) Nonstructural damage
Severe nonstructural damage in which ceiling members were widely dropped, as
observed in the investigation for the high school gymnasiums, was not observed in theelementary and junior high school gymnasiums. However, 20 of the gymnasiums sufferedsome sort of nonstructural damage. The degree of nonstructural damage in the elementaryand junior high school gymnasiums seems to be smaller than in the case of high school
gymnasiums.
6.4.4 Classification and characteristics of damage to steel gymnasiums
During this earthquake damage investigation, a total of 66 gymnasiums in the highschools within Ibaraki prefecture and in the elementary and junior high schools within
Mito city were surveyed. The damage to the gymnasiums was classified into the types of(1) to (7). The types of (1) to (6) and the type of (7) represent structural damage andnonstructural one, respectively.
(1) Buckling and fracture of brace member and fracture of its joint(2) Buckling of diagonal member of latticed column(3) Damage of connection (bearing support part) between RC column and steel roofframe(4) Deflection, buckling and fracture of roof horizontal brace(5) Cracking of column base concrete(6) Other (Overturning of floor strut, etc.)(7) Nonstructural damage such as dropping of ceilings and exterior walls and breakage ofwindows
Each damage photograph shows each damage type in the following pages.
(1) Buckling and fracture of brace member and fracture of its joint
Buckling of brace member (Photo 6.4-1) and fracture of brace joint (Photos 6.4-2 ~6.4-4) were observed. Angle section was often used for many brace members, but circularhollow section steel (Photo 6.4-3) was also used for brace members. Fractured sections
include steel plate inserted into steel pipe, end of bracing member and section loss part bybolt hole. These types of the damage are classified into the severe damage category basedon the damage evaluation standard6.4-4). The number of the gymnasiums of this type is 3.
The gymnasiums constructed under the previous seismic code that were severely damagedby the Mid Niigata Prefecture Earthquake in 2004 had accounted for about 30% of thetotal6.4-1)~6.4-3). It is impressed that a rate of the gymnasiums severely damaged by the 2011
Tohoku earthquake was lower than by the Mid Niigata Prefecture Earthquake in 2004.

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Photo 6.4-1 Buckling of brace

Photo 6.4-2 Net section fracture at bolt
hole(a) Fracture at column top(b) Fracture at brace crossing

Photo 6.4-3 Fracture of brace welded connection

Photo 6.4-4 Fracture of bolts-93-

(2) Buckling of diagonal member of latticed column
In one of the investigated gymnasiums, buckling of diagonal members in somelatticed columns was observed (Photo 6.4-5). Damage of column buckling caused in steel
frames for span direction had not been observed under the damage investigations of the
Mid Niigata Prefecture Earthquake in 20046.4-1)~6.4-3).

(a) Latticed column(b) Buckling of diagonal member

Photo 6.4-5 Buckling of diagonal member of latticed column(3) Damage of connection (bearing support part) between RC column and steel roofframe
In the investigated gymnasiums, exposure of anchor bolts due to spalling of theconcrete at connection (bearing support part) between the RC column and steel roof
frame (Photos 6.4-6 and 6.4-7), spalling of finish mortars on the RC column at the roof
bearing support part, and pullout of hole-in anchors (Photo 6.4-8) were often observed.

Photo 6.4-7 Spalling of concrete

Photo 6.4-6 Spalling of concrete-94-

Photo 6.4-8 Pullout of hole-in anchors(4) Deflection, buckling and fracture of roof horizontal brace
Roof horizontal braces were damaged in two high school gymnasiums and fiveelementary and junior high school gymnasiums. Such damage mainly occurred athorizontal braces with turnbuckles; obvious deflection of the horizontal brace (Photo
6.4-9) and fracture at thread and fracture of bolt connections were observed (Photo
6.4-10).

Photo 6.4-9 Deflection of horizontal
bracesPhoto 6.4-10 Fracture of horizontal
braces(5) Cracking of column base concrete
Damage of cracking of the column base concrete and mortar in the gallery of some
gymnasiums was observed (Photo 6.4-11). Concrete and mortar of steel column base at a
ground level was also cracked (Photo 6.4-12). However, almost all of these cracking areclassified into minor or slight damage.

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Photo 6.4-11 Cracking of columnbase concrete

Photo 6.4-12 Cracking of column baseconcrete(6) Other (Overturning of floor strut, etc.)
As the other types of the structural damage, the following damage was observed; (a)overturning of floor strut (Photo 6.4-13), (b) tilting of concrete block self-standing walland (c) peeling of paint of beam members which was observed near the top of the
V-shaped roof beams or arch beams (Photos 6.4-14 and 6.4-15). In terms of the peeling ofpaint, it is uncertain whether yielding of the beams occurred or not.

Photo 6.4-13 Overturning of floor strut

Photo 6.4-14 Peeling of paint of beams

Photo 6.4-15 Peeling of paint of beams-96-

(7) Nonstructural damage such as dropping of ceilings and exterior walls andbreakage of windows
The types of nonstructural damage of gymnasiums include dropping of ceilings andlighting equipment (Photos 6.4-16 ~ 6.4-18), breakage of windows (Photo 6.4-19),
dropping of exterior walls (Photo 6.4-20), dropping of interior walls and eave soffit(Photo 6.4-21). In particular, the severe damage such as dropping of extensive ceiling in
the high school gymnasiums was observed more than in the elementary and junior highschool gymnasiums.

Photo 6.4-16 Dropping of extensive
ceiling components

Photo 6.4-17 Dropping of extensive ceilingcomponents

Photo 6.4-18 Dropping of extensive ceiling components

Photo 6.4-19 Breakage of windows-97-

Photo 6.4-20 Falling of exterior finish
components

Photo 6.4-21 Falling of eave soffit

6.4.5 Conclusions
The damage to the steel gymnasiums constructed under the previous seismic codein the areas with JMA seismic intensity around 6 in Ibaraki prefecture was investigated,
and the outline of the investigation was described in this section. The results of thedamage investigation of the steel gymnasiums are summarized as follows.
a) Structural damage to the steel gymnasiums
1) The types of observed structural damage to the gymnasiums are classified into thefollowing six categories. (1) Buckling and fracture of brace member and fracture of its
joint, (2) Buckling of diagonal member of latticed column, (3) Damage of connection(bearing support part) between RC column and steel roof frame, (4) Deflection,
buckling and fracture of roof horizontal brace, (5) Cracking of column base concrete,and (6) Other (overturning of floor strut, etc.).
2) In three among the 66 investigated gymnasiums, severe structural damage such as"fracture of brace member and joint" occurred. This rate of the damage seems to besmaller than that in the Mid Niigata Prefecture Earthquake in 2004.
3) Severe structural damage was observed in Mito city, Hokota city and Naka city than inother areas.
b) Nonstructural damage to the steel gymnasiums
1) The types of observed nonstructural damage include dropping of ceilings, dropping of
exterior and interior walls, falling of eave soffit and breakage of windows.
2) In four of the investigated gymnasiums, ceiling materials were extensively dropped,
which is classified into the severe damage category. In some of the gymnasiums, many
windows were broken.
3) Severe nonstructural damage was observed in Mito city, Hokota city and Hitachi city
than in other areas.

-98-4) Severe structural and nonstructural damage seems to occur in the high school
gymnasiums rather than in the elementary and junior high school gymnasiums.
References
6.4-1) NILIM, MILT, Japan and BRI, Japan: Report on the Damage Investigation of
Buildings Due to the Mid Niigata Prefecture Earthquake in 2004, pp.305-353,
October, 2006 (in Japanese)
6.4-2) Takashi Hasegawa, Akiyoshi Mukai, Kazuo Nishida and Tadashi Ishihara:
Damage Investigation of Steel Gymnasiums Due to the Niigataken-chuetsu
Earthquake (Part1 Study on structural damage), Summaries of Technical Papers ofAnnual Meeting, AIJ, B-2, pp.569-570, September, 2005 (in Japanese)
6.4-3) Kazuo Nishida, Akiyoshi Mukai, Takashi Hasegawa and Tadashi Ishihara:
Damage Investigation of Steel Gymnasiums Due to the Niigataken-chuetsu
Earthquake (Part2 Study on nonstructural damage), Summaries of Technical Papersof Annual Meeting, AIJ, B-2, pp.571-572, September, 2005 (in Japanese)
6.4-4) The Japan Building Disaster Prevention Association: Damage evaluation standard
and repair technology guidelines of earthquake damaged buildings, August, 2002
(in Japanese)-99--100-

6.5
6.5.1

Damage to Residential Land
Introduction

The outline of damage situations associated with liquefaction in the alluvial plainarea along the Tone River on the border between Ibaraki and Chiba prefectures and in
Urayasu city, Chiba prefecture is reported. Furthermore the outline of damage situationsof developed housing areas in Miyagi and Fukushima prefectures is also reported.
6.5.2

Damage due to Liquefaction in alluvial plain area along Tone River

Damage associated with liquefaction has occurred in the same areas as in the areas
where liquefaction had been reported in past earthquakes, such as abandoned river
channel, back marsh and reclaimed paddy field. This section describes the damage
situations in Nishishiro, Inashiki city, Hinode, Itako city and Kamisu city in Ibaraki
prefecture. Liquefaction damage in Nishishiro, Inashiki city and Hinode, Itako city had
been reported in the 1987 East Off Chiba Prefecture earthquake.
(1)

Nishishiro, Inashiki city, Ibaraki prefecture
Large-scale and extensive damage occurred within the area of 500 m by 500 m
that encloses route 51 of national highway and the Yokotone River on the east of theroad. Route 11 of prefectural road was closed to vehicles, and sand boiling, large-scaleroad upheaval or severe fissure that is associated with liquefaction was seen mainly
along the road. As a ground deformation, the ground subsided up to about 40 cm, andlateral displacement was up to about 1 m. Automobile was buried in boiled sand to theextent of a half of height of their tires.
Finishes of the sidewalks around a large-scale commercial establishment along
Route 11 were scattered. The subsidence of the surrounding ground was about 40 cm,
and the settlement of the facility in itself was slight. The commercial building was tilted
about 0.7/100 in the longitudinal direction. The pile foundation type of the building wasobserved from an opening between surrounding fissures (Photo 6.5-1).

Photo 6.5-1 Situations around the commercial building and state of pile head-101-A boiled sand was seen everywhere on the roads or sites also in surrounding
residential area. A house constructed on an embankment was tilted to an adjacent
warehouse with sand boiling. An angle of tilting was 5.0/100 (Photo 6.5-2).
(2)

Hinode, Itako city, Ibaraki prefecture
In Hinode, large-scale damage occurred in the area of about 200 m by 200 m
along the Hitachi-tone River. Boiled sand, uplift of buried structures, and subsidence ortilting of utility poles, which were caused by liquefaction, were seen everywhere on thesite. Many houses facing to the road subsided 20 to 30 cm from the front sidewalk(Photo 6.5-3). Foundation cracks or gaps were not observed.

Photo 6.5-3 Subsidence of two
houses enclosing vacant land

Photo 6.5-2 House tilted 5.0/100(3)

Kamisu city, Ibaraki prefectureThis section describes the damage situations around Yokose Elementary School,
and in Tsutsui, Horiwari and Fukashiba areas.
1)

Around Yokose Elementary School
Yokose Elementary School is located about 3 km southeast from the Kamisu city
office. The boiled sand by liquefaction was seen on the ground near the school. The
ground subsidence caused about 15 cm of difference in level on the rim of the building,and about 40 cm of difference in level at the outer slope (Photo 6.5-4). The building is
supported by pile foundation. The outer slope and stairs were spread foundations, andthe differential settlement was caused in this building.
2)

Tsutsui area
The types of damage, such as sand boiling, uplift of buried structures, road gaps
and subsidence or tilting of utility poles which were caused by liquefaction, occurred in
the area of about 300 m by 300 m near Sotonasakaura in the area of Tsutsui that is
located in the western part of Kamisu city. Due to damage to residential land, a severe
fissure was generated, a house subsided approximately 15 cm from the surrounding-102-

ground and caused about 30 cm of difference in level from the ground (Photo 6.5-5).
Cracking or crack fissures on the foundations were not visually observed.
3)

Horiwari area
The uplift and the gap caused by site ground subsidence occurred in the area of
about 500 m by 500 m along Route 124 of national highway in Horiwari area that is
located in the western part of Kamisu city. Along a street in the center of the area, upliftof the sidewalk or subsidence of the housing site caused a 25 to 30 cm of difference inlevel, and a side ditch around the house was damaged (Photo 6.5-6). A case where theground around a house subsided about 15 cm without settlement of the house wasobserved. It is considered that the lower part of the sidewalk was damaged by the upliftof culverts.
4)

Fukashiba area
Fukashiba is located in the western part of Kamisu city and on the opposite side of
Horiwai along Route 124. In this area, many houses were damaged due to grounddeformation and embankment deformation. Most of the damage patterns of the houses
seem to have included their movement, subsidence and tilting without structural damageon their upper structures or foundations (Photo 6.5-7).

Photo 6.5-4 Slope difference in level

Photo 6.5-5 Crack in the site

Photo 6.5-6 Damage of side ditch

Photo 6.5-7 Damage situations
by liquefaction-103-6.5.3 Damage due to Liquefaction in Urayasu city, Chiba prefecture
A reclaimed ground accounts for 3/4 of a total area in Urayasu city at present. The
southern part of the city is the area that was developed under a reclamation project using
sea sand. In the result, the area consists of soft layers up to GL-40 m. For reference,liquefaction damage was also reported in the 1987 East Off Chiba Prefecture earthquake.
The damage situations are given below.
(1)

Mihama area
In Mihama, subsidence and tilting were observed in houses that have a dry area inthe basement (Photo 6.5-8). An angle of tilting of the house was about 3 degrees. It isconsidered that the basement was uplifted and another remaining parts of the house wassubsided. Around the house, in-site of house was totally covered with boiled sand byliquefaction, and a foundation of fence at site boundary was deformed. In addition, a
carport in one building was ruptured and moved (Photo 6.5-9). A unit of the carport andthe building was separated and moved about 50 cm due to the movement of the groundassociated with liquefaction.
(2)

Benten area
Significant tilting and subsidence of houses was observed at a zone in Benten(Photo 6.5-10). In another zone, the ground subsided by liquefaction, there weredamage to which the road waved and a 10 cm of difference in level was generated
between a side ditch and the road. These types of damage were concentrated on an
extension line of the boundary between the sites of tilted houses. Inhabitants told us that
there was an old river on a straight line where the damage was concentrated.

Dry area

Photo 6.5-8 Tilted house

Photo 6.5-9 Moved carport-104-

Photo 6.5-10 Settled
and tilted house

(3)Irifune area
In Irifune, a difference in settlement between adjacent buildings on spread andpile foundations was observed. The building on spread foundation settled about 35 cm
from the front sidewalk, while the case of building on pile foundation was about 30 cm
of difference in level from the front sidewalk (Photo 6.5-11). Other settled and tiltedbuildings were dotted.
(4)

Hinode area
In Hinode, the ground subsidence was observed (Photo 6.5-12). This building is
considered to have a pile foundation. A relative gap between the building and ground
was about 50 cm. Building lifeline was damaged due to ground subsidence anddisplacement.

Pile foundation

Spread foundation

Settlement
about 35cm

About 30cm

Photo 6.5-11 Difference in damage
due to support mechanisms

Photo 6.5-12 Building with subsidence ofsurrounding ground-105-6.5.4

Damage to Developed Housing Area

The damage investigation for developed housing area was conducted in several
areas of Miyagi, Fukushima and Tochigi prefectures, while only the damage in Miyagi
and Fukushima prefectures is reported in this section.
(1)

5-chome, Oritate, Aoba-ku, Sendai city, Miyagi prefecture
In one corner of a large-scale housing area, where a slope in the N-NE direction
had been developed, ground deformation by sliding of the reclaimed area by banking to
the slope direction, and damage to the retaining walls by ground deformation were often
observed (Photo 6.5-13). Houses on the site were recognized to have different damage
patters, such as movement, subsidence and tilting without structural damage, severe
structural deformation and fractured foundation.
(2)2-chome, Aoyama and 4-chome, Midorigaoka, Taihaku-ku, Sendai city,
Miyagi prefectureThis area is located at one corner of the large-scale housing area where acontoured hill was developed. Ground deformation by sliding of the reclaimed area bybanking to the slope direction, and damage to the retaining walls by ground deformation,
were often observed. The damaged area in 4-chome, Midorigaoka during the 2011
Tohoku earthquake was almost same as that during the 1978 Miyagi-oki earthquake.
The land in 2-chome, Aoyama is wavier than in 4-chome, Midorigaoka. Near the zoneof 2-chome, Aoyama, large-scale sliding of the embankment occurred (Photo 6.5-14). In
this zone, large deformation and damage were seen on both of upper structures andfoundations of houses in the housing area. In other places with embankment sliding,deformation and damage to upper structures of houses were observed, but it seemed that
there was limited significant damage to foundations. In 2-chome, Aoyama, a retaining
wall for the housing area with a height of over 5 m was damaged.

Photo 6.5-13 Damage to retaining
wall and house by sliding and grounddeformation

Photo 6.5-14 Group of houses damaged
by sliding and ground deformation

-106-

(3)

1-chome, Futabagaoka, Aoba-ku, Sendai city, Miyagi prefectureThis area is located at one corner of a large-scale housing area where a slope inthe eastern direction was developed. The area suffered ground deformation by sliding of
the reclaimed area by banking to the slope direction. Large structural deformation(Photo 6.5-15) was relatively often seen in houses on the area, but houses without
structural damage were sporadically observed. In addition, a gap between the housefoundation and surrounding ground that was caused by ground subsidence andtransformation, and damage to the lifeline, were observed. Damage to a retaining wall in
the area was hardly seen, while traces of flaking and falling of block fences on the upper
part of the wall were sporadically observed.

(4)

1 to 2-chome, Midorigaoka, Shiroishi city, Miyagi prefectureThis is a housing area where a hill was developed. Fissures on the slope of the hill
and near the top of the hill, and damage to housing foundations and retaining walls by
deformation of the reclaimed area by banking, were observed in the area. The slope in
1-chome, Midorigaoka had been significantly collapsed under the 1978 Miyagi-oki
earthquake. A level of ground deformation on the slope under the 2011 Tohoku
earthquake was lower than that during the 1978 earthquake. Near at the top of the hill,
ground deformation of the reclaimed area by banking caused fracture of theembankment retaining wall, damage to house foundations (Photo 6.5-16) and push-outof the retaining wall on embankment.

Photo 6.5-15 Damage to houses bysliding and ground deformation

Photo 6.5-16 Houses damaged near
the top of hill

(5)

Shimomiyamae, Asohara Yamamoto Town, Watari-gun, Miyagi perfectere
This is a housing area where a hill was developed. Land sliding of the slope at theend of the hill, and ground deformation that seemed to be related with the sliding wereobserved. This ground deformation caused serious damage to houses. In the result, somehouses were in a state of sliding on the slope of the hill (Photo 6.5-17). On the other
hand, there was no ground deformation in a house located in the flat part of the hill,while paper sliding doors on the first-story window were only broken in the houseduring the earthquake.

-107-

(6)

Numanoue, Fushiogami, Fukushima city, Fukushima prefectureThis area is located at one corner of a large-scale housing area where a hill wasdeveloped. The result of investigation was revealed ground deformation by land sliding
on the slope of the hill. This ground deformation caused serious damage to houses. In
the result, several houses were in a state of sliding on the slope of the hill (Photo 6.5-18).
On the other hand, houses near the top of the hill suffered only damage associated withslight deformation of the reclaimed area by banking.

Photo 6.5-17 Fracture of embankment
retaining wall and houses tilting byland sliding on the slope of hill end
6.5.5

Photo 6.5-18 Land sliding of slope on
the southwest of hill and sliding houses

Conclusions
The outline of the damage situations in the investigate scope is as follows.

(1)

Damage due to liquefaction:
In the alluvial plain area of the Tone River and the coastal area of Tokyo Bay,
extensive damage such as sand boiling or ground deformation associated withliquefaction was confirmed. Heavily tilted houses were seen, while cracks or fissures on
the foundations were not observed.
(2)

Damage to developed housing area:
Severe damage with ground deformation such as slope sliding was observed
mainly in the elevated and developed housing area (particularly marginal part ofdevelopment). In several areas, ground deformation occurred again in the developedarea that had been affected by the past earthquakes.
ACKNOWLEDGEMENT
Photos 6.5-1(left and right) and 6.5-2 are provided through the courtesy of Mr.
Kuze and Mr. Yokawa (Center for Better Living). We express our gratitude to them.

-108-6.6 Damage to Nonstructural Components
6.6.1 Introduction
This section is based on the surveys by the Joint Survey Team after March 11th 2011.
External surveys were conducted to various buildings in three prefectures of Miyagi,
Fukushima and Ibaraki, and external and internal ones were also done in Ibaraki
prefecture to gymnasiums and an airport passenger terminal building. This section
describes the outline of the damage to exterior walls, openings, suspended ceilings,
interior walls focusing on the buildings without severe structural damage patterns such as
story collapse.
6.6.2 Damage to exterior walls
There were observed many damaged exterior walls, which included walls finishedwith ceramic wall tiles, cement mortar and metal lath wall and AAC (Autoclaved
lightweight Aerated Concrete) panel walls.
Detachment of ceramic wall tiles was often observed at buildings of RC
nonstructural exterior walls. Types of the detachment are classified according toexistence or nonexistence of crack on the damaged RC wall.6.6-1) 6.6-2) In Photo 6.6-1,
ceramic wall tile detached from RC exterior wall. Cracks were observed on the damaged
RC wall. Photo 6.6-2 shows detachment of ceramic wall tiles installed on a cylindrical
RC wall above the building entrance (within a circle). No crack was externally observedon the undersurface RC wall. A net was placed over the damaged area to catch fallingtiles.

Photo 6.6-1 Detachment of ceramic walltiles from damaged RC exterior wall

Photo 6.6-2 Detachment of ceramic walltiles from RC wall-109-

Damage to cement mortar and metal lath exterior walls was often observed in steelbuildings. Photo 6.6-3 shows detachment of cement mortar and metal lath exterior wallin a 3-story building. Damage to the window glass was not observed, but cement mortar
and metal lath fell from the exterior wall (shown in Photo 6.6-3) and from the parapet on
another side. Photo 6.6-4 shows an one-story steel building in which cement mortar andmetal lath detached from an exterior wall and from an eaves soffit. Photo 6.6-5 shows adamaged gable end wall of a gymnasium. This wall consisted of two layers. The
undersurface wall was cement mortar and metal lath exterior wall. The surface one wasexterior boards nailed to furring installed on the undersurface wall. Both were damaged
and fell by the earthquake.

Photo 6.6-3 Falling of cement mortar andmetal lath wall

Photo 6.6-4 Falling of cement mortar andmetal lath from eaves soffit

Photo 6.6-5 Damage to gymnasium gable end wall
Photo from 6.6-6 to 6.6-7 shows damage to AAC panel exterior walls. Photo 6.6-6
shoes falling of finishing ceramic wall tiles on AAC panels and broken light-weightaerated concrete in a 3-story building. Ceramic wall tiles on all faces of the exterior walls
detached and the corners of the AAC panels were chipped. AAC panel was broken andinternal iron wires were exposed at the circular broken line in the photo. AAC panels fell
from another side. The construction method of the AAC panel exterior wall was not-110-observed in the external survey. Photo 6.6-7 shows falling of AAC panels from the
top-floor of a 5-story building. The damaged AAC panels were observed to be installed
to the support metal with cement mortar and steel bar. This AAC construction method
appeared in 3rd edition of Japanese Architectural Specification Standard JASS 12 as oneof standard construction methods for AAC panel exterior wall but did not in its 4thedition. 6.6-3) 6.6-4) AAC panels installed with this AAC construction method were
frequently observed to be damaged.

Photo 6.6-6 Falling of ceramic wall tiles
and breakage of AAC panels

Photo 6.6-7 Detachment of AAC panels

6.6.3 Damage to openings
Damage to openings was observed in window glasses and window frames.
Photo 6.6-8 shows broken window glasses in the upper area of a windbreak room on
the ground level of a 5-story building. Exterior wall ceramic wall tiles fell from anotherside.

Photo 6.6-8 Broken window glass-111-

Photo 6.6-9 shows damaged window glasses installed to the upper fixed window
with hardening putty at a gymnasium gable end wall. Cracked wired window glasses
were also observed at the lower double sliding window with hardening putty. Flaking ofpaints was observed on the center of an arch beam of the gymnasium. Photo 6.6-10
shows breakage of window glasses in a gymnasium. The window glasses were installed
to fixed window frames with glazing bead and twelve window glasses were broken at
three exterior surfaces. There were observed flaking of concrete at the roof bearing
support part, deformation of almost all roof horizontal braces and fracture of one roof
horizontal brace in the gymnasium.

Photo 6.6-9 Breakage of window glasses
installed to fixed window frame withhardening putty

Photo 6.6-10 Breakage of window glasses
installed to fixed window frame withglazing bead

Photo 6.6-11 shows broken window glasses on the longitudinal surface in a
gymnasium. Twenty-six wired window glasses were broken, which were installed to
double sliding window frames with glazing bead. On the opposite side windows, there
was no damage to the frosted window glasses and a detachment of a mullion cover of awindow. No damage was observed in the structure.

Photo 6.6-11 Breakage of wired window glass installed to double sliding window framewith glazing bead-112-

Photo 6.6-12 shows a damaged glass wall system at the 1st floor of a 6-story
building. A glass mullion was broken in an area circled by a broken line (steel pipe
adjacent to the broken glass were installed after the earthquake for the repair work).
Photo 6.6-13 shows damage to window frame in a gymnasium. The photo shows thewindow frames near the center of the longitudinal surface of the gymnasiums. The upper
part of the window frame was dislocated and leaned to the outside. The same damage
was observed also at the opposite side. Fracture or buckling was observed in most of thesection loss parts by bolt holes on longitudinal direction frame braces. Braces werefractured in three of four frames.

Photo 6.6-12 Breakage of glass mullion of Photo 6.6-13 Dislocation of window frame
glass wall system

6.6.4 Damage to suspended ceilings
Many damaged suspended ceilings were observed in the damage investigation ofgymnasiums and an airport passenger terminal building. The damaged suspended
ceilings include wooden suspended ceilings faced with wooden boards, metal furring
ones faced with plaster boards and absorption boards of rock wool, ones with exposed T
system and glass wool boards and others.
Photo 6.6-14 shows a damaged wooden suspended ceiling in a gymnasium. The
ceiling almost fell with light fittings except at perimeter. Partial falling of an eaves soffit,
dislocation of a window frame and 33 broken window glasses were also observed.

-113-

Photo 6.6-14 Falling of wooden suspended ceiling
Photo 6.6-15 shows a metal furring suspended ceiling broken at the center of apitched ceiling. Damage was also observed at interior walls above the stage. No
damage was observed to the steel roof and supporting RC columns. Photo 6.6-16 shows
damage to a high ceiling above the lobby of an airport passenger terminal building.
There were five metal furring suspended ceilings in 3m x 11m. The metal-sheet clips
hanging the metal furring channels were damaged by the earthquake and one of theceilings fell. In the ceiling plenum, vertical diagonal members were unevenly installed
and the members were complicatedly installed near the connection with the surrounding
wall. No damage to the structure was observed.

Photo 6.6-15 Falling of metal furring
suspended ceiling

Photo 6.6-16 Falling of metal furring
suspended ceiling

Photo 6.6-17 shows damaged ceilings in a gymnasium. The horizontal ceilingmarked with red dotted lines was composed of corrugated steel plates and steel members
and the pitched ones were composed of metal furring channels and other steel members
faced with gypsum board. Both ceilings fell. The broken window glasses and the leaned
interior wall above the stage were also observed. Many roof horizontal braces werefractured.

-114-

In the gymnasium shown in Photo 6.6-18, many glass wool boards on exposed T
system fell. Flaking of concrete was observed in the structure.

Photo 6.6-17 Falling of metal furring
suspended ceiling and corrugated steel
platesPhoto 6.6-18 Falling of glass wool boardof T system ceiling

Photo 6.6-19 shows a damaged metal furring suspended ceiling in a gymnasium.
Significant visual damage was not observed, but the ceiling board sagged near the centerof pitched ceiling marked with a red dotted oval line in the photo. This was possibly due
to the displacement of ceiling members in the plenum. Cement mortar finish of interiorwall above the stage was flaked as shown in Photo 6.6-23, and the exterior boards werebroken at the gable end wall. No damage to the structure was not observed.
Photo 6.6-20 shows damaged ceiling at the connection with surrounding wall in a
gymnasium. Bending of the metal furring channels and detachment of ceiling boards
were observed. In the corner of the ceiling, the sheet-metal clips were damaged and theceiling sagged in several meters long. The gymnasium is composed of lower RC frame
and upper steel frame.

Photo 6.6-19 Sagging of metal furring
suspended ceiling

Photo 6.6-20 Damage to metal furring
ceiling at the connection wall-115-

Photo 6.6-21shows damaged ceiling boards at the connection with the structure of a
gymnasium. It was reported that one window glass was broken. No damage to thestructure was observed.
Photo 6.6-22 shows damaged ceilings at an office building. The ceiling wasdamaged at the connection with the partition. Bending of a metal furring channels andfalling of ceiling boards were observed.

Photo 6.6-21 Damage to metal furring
suspended ceiling at the connection

Photo 6.6-22 Damage to metal furring
suspended ceiling at the connection

6.6.5 Damage to interior walls
Photo 6.6-23 shows damaged walls above the stage in the gymnasium shown in
Photo 6.6-19. Cement mortar finishes on the studs were broken and fell. Damage to thewalls above the stage was observed also in some gymnasiums such as shown in Photo
6.6-15 or Photo 6.6-17.

Photo 6.6-23 Falling of cement mortar finish above stage
Photo 6.6-24 shows a lift of the nail fixing interior wall boards to the studs in thearena of gymnasium.
Photo 6.6-25 shows damaged interior walls in a gymnasium. Interior walls around-116-the supports leaned at two of three basketball hoops.
temporarily supported with ropes.

Photo 6.6-24 Loosen nails fixing board

The damaged hoops were

Photo 6.6-25 Damaged interior wall

6.6.6 Conclusion
This section described the outline of damage to nonstructural components. Damage
to nonstructural components constructed with relatively older building methods wasoften observed. Breakage and falling of nonstructural components placed on relatively
high points were also observed.
The frequently observed damage to each nonstructural component is summarized as
below:
Exterior wall
Ceramic wall tiles were detached at RC nonstructural walls. Cement mortar and metallath were detached at steel buildings. AAC panels installed to support metal withcement mortar and steel bar were also detached at steel buildings.
Openings
Window glasses were broken at fixed window, mostly installed with hardening putty.
Suspended ceiling
Various types of suspended ceilings were damaged. Breakage at connection withinterior walls was frequently observed at gymnasiums.
Interior wall
Walls were broken and fell above the stage at gymnasiums.

-117-References
6.6-1) Manual for Seismic Design of Exterior Walls – For Mid-rise Buildings -, 2ndedition, supervised by Building Guidance Division, Housing Bureau, Ministry ofConstruction and Japan Conference of Building Officials, published by Building
Center of Japan, 1998
6.6-2) Akio BABA and Hiroshi ITO, Full Scale Experiment on the Seismic Safety ofExterior Finishing Material and Construction Method, Cement & Concrete No.376,
published by the Cement Association of Japan, 1978
6.6-3) Japanese Architectural Standard Specification JASS 21 AAC Panel Work, 3rdedition, Architectural Institute of Japan, 1998
6.6-4) Japanese Architectural Standard Specification JASS 21 AAC Panel Work, 4thedition, Architectural Institute of Japan, 2005

-118-

7.
7.1

Damage to Buildings in Inundation Areas Induced by Tsunami
Introduction

The purpose of this investigation is to understand an overview of buildings
damaged by tsunami, to obtain basic data and information required to evaluatemechanisms for causing damage to the buildings and to contribute to tsunami load andtsunami-resistant designs for buildings such as tsunami evacuation buildings, by meansof collecting building damage cases by tsunami, classifying the damage patterns fordifferent structural categories, and making a comparison between the calculated tsunami
force acting on buildings and the strength of the buildings.
The tsunami damage survey team* organized in the Joint Survey Team consists of
27 members, for voluntary investigation. The team collected national and international
standards and codes concerning tsunami evacuation buildings and tsunami loads andsurveyed about 100 buildings and structures in three site investigations.
7.2

Classification and Discussion of Damage Patterns

7.2.1 Reinforced concrete buildings
1) Collapse of first floor
A case where column capitals and bases on the first floor in a building were
subject to bending failure and subsequently to story collapse was seen in 2-story
buildings (Photo 7.2-1).
These buildings have column-to-beam frames. The first floor has a relatively
small number of walls, but many concrete block walls are placed on the second floor.
The first and second floors of the building in Photo 7.2-1 are used as shop and dwelling,respectively. The relevant buildings are estimated to have structural characteristics oflow strength and stiffness on the first floor. As an opening on the second floor is notlarge, it is assumed that the second floor suffered a large tsunami wave pressure and theshear force acting on the first floor exceeded the lateral load-bearing capacity, resulting
in the collapse of the building. Story collapse of the first floor has not been observed in
3-story or higher buildings in the investigations. In 3-story buildings, in general,
reinforced concrete walls are often used for the first floor. Therefore, the strength of thefirst floor of 3-story buildings is considered to have been larger than that of 2-story
buildings.

-119-Photo 7.2-1 Story collapse of a 2-story reinforced concreted building2) Overturning
Overturning was observed in 4-story or lower buildings. In all overturnedbuildings, the maximum inundation depth exceeded their height. Overturning types
include building that fell sidelong (Photo 7.2-2) and buildings that turned upside down.
Most of the overturned buildings are of mat foundation. In some overturned buildings
on pile foundation, piles were pulled out.

Photo 7.2-2 Overturning of a 3-story reinforced concrete building
Overturning cases were often seen in 4-story or lower buildings with relatively
small size of openings. However, there were many cases where 4-story or lower
buildings with large size of openings were not overturned. Consequently, the size of
opening on an exterior wall is considered to have greatly affected overturning.
In some cases, there were tsunami traces at the heights of the upper end of
openings on the top floor inside the buildings whose heights were exceeded by
maximum inundation depths. It is considered that air has accumulated in the space
between the ceiling and the upper end of openings. Overturning is considered to occur
when an overturning moment by tsunami wave force exceeds an overturning strength bya dead load of a building (considering the effect of buoyancy as required). A building, inwhich the distance from the upper end of an opening on each floor to a ceiling is long,-120-

may be overturned even by a slight horizontal tsunami force when buoyancy
significantly acts on the building.
3) Movement and washout
Most of the overturned buildings were moved from their original positions. It isestimated that large buoyancy acted on the buildings. Moved and overturned buildings
left no dragged traces on the ground. One of the buildings moved over a concrete block
fence with about 2m height on an adjoining land without destroying the fence (Photo
7.2-3). The building seems to have floated up by buoyancy. Some of the 2-story
apartment houses with the same shape that were overturned were washed away andmissing. A buoyancy and large horizontal force seem to have acted on these buildings.

Photo 7.2-3 A 2-story reinforced concrete building that moved over the fence andoverturned4) Tilting by scouring
When tsunami acted on a building, a strong stream was generated around thecorner of the building, resulting in many large holes on the ground that were bored byscouring. In one case, a building on mat foundation fell into a hole bored by scouring(Photo 7.2-4).

Photo 7.2-4 A 2-story reinforced concrete building that was tilted by scouring-121-5) Fracture of wall (fracture of opening)
When tsunami acts on openings in a building and openings of the opposite side of
the building are smaller than the affected openings, a stream flowing from the affected
openings concentrates on the opposite small openings. In one observed case related tothis event, a stream generated by tsunami provided a large pressure to a reinforced
concrete non-structural wall around small opposite openings. The pressure enlarged theconcrete wall to the outside and fractured the wall reinforcement. A tsunami wave force
that acts on a building will be reduced if the size of opening affected by the force
becomes larger. The same trend is considered to apply to an outlet surface of the stream.
A case where such wall reinforcement was fractured is often seen in wall
members with single layer bar arrangement. In one damaged building (Photo 7.2-5), a
300 mm-thick shear wall with double layer bar arrangement and a support span of morethan 10 m and without the second and third floor slabs was bent inside by tsunami wave
pressure. However, a shear wall in an area (Photo 7.2-5 Back of the building, right-handside), where there is a floor on the second story and a support span is not long in thesame building, was not bent.

Photo 7.2-5 Out-of-plane fracture of reinforced concrete shear wall without floor6) Debris impact
Debris impact was seen in most of the non-structural members such as window
and ceiling materials. The number of cases of clear damage to skeletons was not large,
but in one observed case, a multi-story wall in an apartment house was probably boredby debris impact (Photo 7.2-6).

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Photo 7.2-6 Wall opening generated by debris impact
7.2.2 Steel buildings
1) Movement and washout by fracture of exposed column base
A typical case of building movement and washout is that a building moved andflew due to the fracture of anchor bolts and/or base plates at steel exposed column bases
and the fracture of a weld between the column and the base plate (Photo 7.2-7). In
most cases, a foundation and some column bases were left in a site, but the body of abuilding was moved beyond the site or missing.

Photo 7.2-7 Steel building overturned by fracture of column base anchor bolts
2) Movement and washout by fracture of capital connection
In damage cases relatively often seen a capital connection on the first or second
floor in a building was fractured, then the building was moved and washed away. Whena column base has a large strength like concrete encases type or embedded type, thistype of fracture is considered to occur. In one case (Photo 7.2-8), foundation in abuilding, and several columns on the first floor (or up to the second floor) were left on
the site, and the columns fell in the same direction.
In most cases, welds between diaphragms with lower flanges and the first-floor
columns were fractured and the sections of the columns were exposed. In one building,flanges of the second-floor H-shaped beams were torn. Based on the deformation states-123-

near the column bases, it is estimated that a tensile force acted on the first-floor columns,
and then the first-floor capital connections were fractured after the first floor was
greatly tilted to the same extent as the inclination of the remaining columns.

Photo 7.2-8 First-floor columns falling in the same direction3) Overturning
One case, in which a whole building including foundation is overturned, wasconfirmed. Most of the AAC panels of claddings were left (Photo 7.2-9).

Photo 7.2-9 Overturning of a 3-story steel building4) Collapse
Skeleton collapse including story collapse of the first floor was seen in a 2-story
steel building (Photo 7.2-10). Partial collapse of a warehouse was also seen on the coast.

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Photo 7.2-10 Story collapse of first floor in a 2-story steel building5) Large residual deformation
Slight tilting was often observed with remaining their skeletons in steel buildings.
In one case (Photo 7.2-11), a gabled roof frame building did not collapsed despite large
residual deformation.

Photo 7.2-11 Tilted gabled roof frame6) Full fracture and washout of cladding and internal finishing materials
Cladding materials such as AAC panel were almost fully fractured and washedaway, and then a steel frame as a skeleton was remaining. This case was often observed(Photo 7.2-12). It is considered that an external force that acts on the skeleton became
small due to early washout of the cladding materials. In the remaining building, slighttilting of the skeleton, member deformation on the face affected by tsunami, ormembers locally damaged possibly by debris impact, were observed.

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Photo 7.2-12 A remaining 3-story steel building
In another damage case, openings on the face affected by tsunami and on its
opposite face, or transverse faces were severely damaged and fractured possibly due tostream runoff.
7.3 Database for Investigated Buildings
Outer dimensions of about 100 buildings and dimensions of their skeletons were
measured in the site investigation. Maximum inundation depths were measured fromtsunami traces on surveyed buildings and surrounding buildings. These measurement
results were integrated into a database for investigated buildings. Building name,address, building use, construction year, designation as tsunami evacuation building,
structure category, number of stories, outer dimension, distance from seacoast (river),GPS position, altitude, surrounding circumstances, damage situations, etc., were
included in the database. In addition, photos of investigated buildings that were takenfrom four directions as possible were attached to the database. Based on the database,the joint survey team estimated strengths of the buildings and tsunami loads on them,and is evaluating whether the estimated values are consistent with the damage
situations.

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7.4 Damage to Wood Buildings
7.4.1 Objectives of damage survey
Many of wood buildings built in the Pacific coast of Tohoku region were washedaway by the tsunami caused by the Tohoku Earthquake. However, there were not few woodhouses that remained in tsunami attended areas. The field surveys were conducted to grasp
the outline of the damage to the wood buildings due to tsunami and the characteristics orconditions of the building washed away and remained.
7.4.2 Outline of survey
The field surveys were carried out both in plain area and slope land. The surveyed
area and survey schedule were shown in Fig. 7.4-1 and Table 7.4-1, respectively. However,in the surveyed city and town, we didn’t survey all the area of the city and town
exhaustively, and surveyed only a part of the flooded area selectively. Therefore, what are
mentioned in the followings are the knowledge which was provided in the surveyed area atthe surveyed time.
Ohtsuchi town
Kamaishi city
Oofunato city
Rikuzentakata city
Kesen-numa city
Minami-Sanriku town
Higashi-Matsushima town
Onagawa town
Wakabayashi ward, Sendai city
Natori city
Iwanuma city
Watari town
Yamamoto town

Fig. 7.4-1. Locations of surveyed area
Table 7.4-1. Survey schedule
Category
Plain
area

Surveyed cities and towns
Wakabayashi ward in Sendai city, Natori city, Iwanuma city, Wataritown, and Ymamoto town in Miyagi prefecture

Slope land

Ohtsuchi town, Kamaishi city, Ohfunato city, and Rikuzen-takata city
in Iwate pref., Kesen-numa city, Minami-Sanriku town, Onagawa
town, Higashi-Matsu-shima town in Miyagi pref.

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Date of survey
April 6-8, 2011.
May 25-27, 2011.

7.4.3 Damage in Plain Area
There were few things to block tsunami in plain area, a lot of wood buildings sufferedcrushing damage due to tsunami caused by the 2011 off the Pacific coast Thohoku
Earthquake. The flood water depth in the surveyed area estimated by the flooded water
trace on the building wall was shown Table 7.4-2.
(1) Damage to wood houses
In the area with over 5 m flood water depth, most of the wood houses in theinundated area were washed away by the tsunami. How the houses were washed away; as
for the case which the whole house including foundations was washed away (Photo 7.4-1),
the case which only foundations were left (Photo 7.4-2), the case which sills andfoundations were left (Photo 7.4-3), the case which sills, foundations and floor boards wereleft (Photo 7.4-4), and so on, were observed. There were several cases that the hold down
fastener was failed, as shown in Photo 7.4-5. The foundations or wall of bath room made by
concrete block often remained in, as shown in Photo 7.4-2.
(2) Wood buildings remained in Arahama and Arahama-shin, Wakabayashi ward,
Sendai city
Most of wood houses near the shore were washed away. However, not all the houses
were washed away. For example, many houses which were located far from the shore
remained, as shown in Photo 7.4-6. The houses in the downstream of RC building remained,as shown in Photo 7.4-7.
A line of wood houses remained were confirmed in Arahama-shin, Wakabayashi ward,
Sendai city, as shown in Photo 7.4-8. The front survived house of the line was non-wooden.
The flood water depth in this area was estimated at the level about 4-5 m. On the other hand,wood house which didn’t have survived buildings in the direction where the tsunami came
avoid being washed away, but suffered heavy damage, as shown in Photo 7.4-9. Several
such houses were confirmed in each surveyed area, and they were built by the construction
methods with many metal fasteners.
Table 7.4-2. Estimated flood water depth
Surveyed area
Arahama, Wakabayashi ward, Sendai city
Arahama-shin, Wakabayashi ward, Sendai city
Yuriage, NatoriNorth of Arahama port, Watari town
West of Arahama port, Watari town

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Estimated flood water depth (m)
6-8
5-6
5-6
6
4

Photo.7.4-1. Foundations washed away.

Photo.7.4-2. Only foundation remained.

Photo.7.4-3. Foundations and sills remsined.

Photo.7.4-4. Sills, foundations and floorboards remained.

Photo.7.4-5. Failed hold down fastener.

Photo.7.4-6. Many wood houses remained.

Photo.7.4-7. Wood house remained in the downstream of RC
building in Arahama, Wakabayashi ward, Sendai city.

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Photo 7.4-8. A line of wood houses remainedin Arahama-shin, Wakabayashi ward, Sendai city.

Photo 7.4-9. Remained house which didn’t have survived buildingsin the direction where the tsunami came in Arahamashin, Wakabayashi ward, Sendai city.
(3) Wood buildings to remain in Yuriage, Natori city
Wood buildings also suffered crushing damage due to tsunami, as shown in Fig. 7.4-2.
What parts of buildings remained, for example foundation, sill, and so on, were as same as
mentioned in (1). Figures in rectangles in Fig. 7.4-2 show the locations of buildings
mentioned in the followings. The wood house (Photo 7.4-10:1) united with the foundationand carried away. In the original position of it, steel tube piles remained as shown in Photo
7.4-11(2). Because a temple building (Photo 7.4-12:3) and a steel-frame house (4) weredamaged heavily and remained, tsunami wave force was reduced to some extent, and theneighboring wood house with store avoided being carried away, as shown in Photo 7.4-13(5). It might be possible for the survived low-rise building to make wave force reduce.
In the south east of Hiroura bridge (6), there was protect forest (Photo 7.4-14:7) of
the pine trees with about 20 cm diameter at breast-height. The flood water depth wasestimated to be about 5-6 m by the flotsam attaching to trees. A part of this protect forest
fell down completely, in the downstream of this, the wood house (Photo 7.4-15:8) waswashed away. On the other hand, in the downstream of survived protect forest, woodhouses were selectively carried away and an example of the remained house was shown in
Photo 7.4.16 (9). It seems to be generally thought that protect forest reduces wave force.
However, because it cannot be thought that the strength of trees falling down continuallywas quite different by their location, it would be natural to think that the wave force or the-130-speed of the tsunami were different by factors such as the depth of water or the submarine
topography in this case. There was a house (Photo 7.4-17:10) remained in the area where
has no building and no protect forest existed in the direction of the wave. In addition, therelatively new Japanese conventional post and beam wood house (Photo 7.4-18 :11) andlight frame construction house (Photo 7.4-19 :12) were confirmed at the location where
there were no survived buildings in the direction of waves. Besides, in the downstream of
the former, another Japanese conventional post and beam wood house (13) remained in.
The flood water depth was estimated to be about 3.5 m in these locations.
In the downstream of large RC building, houses with low structural specification (14)also remained, as shown in Photo 7.4-20. On the other hand, in the location where is thedownstream of the relatively large factory building (15), the wood house (16) withrelatively better structural specifications avoided being carried away, selectively.

Photo 7.4-10. Wood house (1) that was
carried away with the basein Yuriage, Natori city.

Photo 7.4-11. Steel tube pile left at thethe original position (2)of photo 7.4-10.

Photo 7.4-12. Heavily damaged temple (3)build ing in Yuriage, Natori
city.

Photo 7.4-13. Wood house with store (5)remained in the downstream of the survived
buildings in Yuriage.

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1
5 4

2
3

17

14
15
16
6
12
13 11

7

9

⑥

8
10

Fig. 7.4-2. Aerial photograph and the location related to surveyed buildingsin Yuriage, Natori city.

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Photo 7.4-14. Protect forest (7) in Yuriage,
Natori city.

Photo 7.4-15. Fallen Protect forest andwood house (8) washed awayin Yuriage, Natori city.

Photo 7.4-16. Protect forest and wood house
house (9) remained in Yuriage.

Photo 7.4-17. Wood house (10) remained
without the effect of protect
forest.

Photo 7.4-18. Japanese conventional post andbeam wood house (11) remainedalone.

Photo 7.4-19. Light frame construction
wood house (12) remained
alone

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Photo 7.4-20. Group of wood houses (14) which were not washed awayin the downstream of a RC apartment house in Yuriage
Factory building

Photo 7.4-21. Wood house (15) which were not washed away
selectively in the downstream of a factory building.
(4) Wood buildings to remain in Arahama, Watari town
Arahama district in Watari town is surrounded with sea shore and faces the Pacific
Ocean in the east, and there is a port in the south side, as shown in Fig. 7.4-3. In the area
between Pacific Ocean and Arahama port, most of wood houses were washed away. In thenorth area of the Arahama port, the flood water depth was estimated to be about 6 m. Manyof wood houses were washed away. On the other hand, in the west area of the Arahama port,
the flood water depth was estimated to be about 4 m. Many of wood houses remained.
What remained, for example foundation, sill, and so on, were as mentioned in (1).
In the area between Pacific Ocean and Arahama port, the wood buildings remained
were Glulam frame structure (Photo 7.4-22) and a mixed structure (Photo 7.4-23) whichhas 1st story of RC structure and wooden 2nd story. In other cases, the part of the L-shaped
wood house (Photo 7.4-24) whose part with short horizontal length in the direction of wave
pressure was washed away, and another part with long horizontal length remained. It was
confirmed that metal fasteners were used in the column end joints, and considered that the-134-structural performance of this house was better.
In the north area of the Arahama port, the 3-story wood house (Photo 7.4-25)
remained. It might be the reason why the lateral strength of 1st story in 3-story building waslarger than that in 2-story building.
In the west area of the Arahama port, it was confirmed that the wood house (Photo
7.4-26) was crashed by two ships but remained. It was the reason why the wave pressure
was low and the structural performance of the house high because the house was relatively
new.

Many of woodhouses remained in.

About 4 m
flood water

depth

Most of wood houses
were carried away.

About 6 m
flood water

depth
Arahama port

Fig. 7.4-3. Aerial photograph and the flood water depth estimatedin Arahama, Watari town.

Photo 7.4-22. Glulam frame structure
Photo 7.4-23. Mixed structure which has
remained in Arahama, Watari1st story of RC structure
town.
and wooden 2nd story.

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Photo 7.4-24. L-shaped wood house whosepart was washed away in theeast of Arahama port.

Photo 7.4-25. 3-story wood house remainedin the north of Arahama port.

Photo 7.4-26. Wood house remained in spite of ship crashing in the west of Arahama port.
7.4.4 Damage in Slope Land
The damage in Akasaki-cho, Oofunato city was reported as an example of thetsunami damage in several surved slope lands. Akasaki-cho is located in the east of
Oofunato bay, and is a gradual slope land. Fig. 7.4-4 shows the aerial photograph and thelocations related to surveyed buildings. Similar to plain areas, many of wood houses were
washed away by tsunami here in Oofunato. According to the resident of the house (Photo
7.4-27:1) located just near the shore, the height of the tsunami reached to the top of 2ndstory, and the house went under the water completely. The house was damaged in a part,however was avoided being carried away. The next work shed (2) whose sill came off fromfloor concrete moved. On the other hand, the 2-story wood house (Photo 7.4-28:3) opposite
to the house (1) across the street along the sea suffered almost no damage. Two houses next
to the house (1) and shed (2) remained, but there is a hill in the back of them (in the northside), and there is a possibility that the hill affect the strength of the wave force caused by
the tsunami. A Japanese traditional post and beam frame house (Photo 7.4-29:5) built on
the street along the sea avoided being carried away under the flood water depth of about 5-6-136-

m, in spite of partial failure of walls. Near this house, the wood house (Photo 7.4-30:6)
remained under about 6 m flood water depth in spite of partial failure in the roof system. It
was considered that this failure caused by the floating materials. There was a house (7)remained in the next, but a house which was guessed to have many hole down fasteners (8)washed away. The house with hold down fastener may not avoid being washed away by thetsunami.
At the location where we went up the slope land from these houses, a lightsteel-frame house (9) remained in under the about 5 m flood water depth. In the next of thishouse, the 1-story old wood house (Photo 7.4-31:10) whose structural specification was not
so good, but the anchor bolts were installed remained. In addition, a warehouse with mud
walls (Photo 7.4-32:11) was remained and an old wood house without anchors (Photo
7.4-33:12) turned and moved horizontally. Because the wood house under about 5 m flood
water depth were almost washed away in plain areas, it might be possible for the slope land
to make lateral force caused by tsunami a little smaller.

1
2

4
5
8

3
6

7

10 11
12
9

Fig. 7.4-4. Aerial photograph and the locations related to surveyed buildingsin Akasaki-cho, Oofunato city.

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Photo 7.4-27. Wood house (1) remained under Photo 7.4-28. Wood house (3) without
the flood water depth of over 7
damage under the floodm in Akasaki-cho, Oofunato city.
water depth of over 7 m in
Akasaki-cho, Oofunato city.

Photo 7.4-29. Japanese traditional woodhouse (5) which was not carriedaway under about 5 m flood
water depth in Akasaki-cho,
Oofunato city.

Photo 7.4-30. Wood house (6) which was
not carried away in spiteof damage on 1st floor roof
system in Akasaki-cho,
Oofunato city.

Photo 7.4-31. Survived house (9) which
seemed to have comparatively
slight structural specifications
in Akasaki-cho, Oofunato city.

Photo 7.4-32. Survived soil warehouse (10)which seemed to have comparatively slight structural
specifications in Akasakicho, Oofunato city.

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Photo 7.4-33. Survived old house (12) which rotated and moved horizontallyin Akasaki-cho, Oofunato city.
7.4.5

Survey summaries
Results of surveys are summarized as follows;
1) Not all of the low-rise wood houses were washed away by the tsunami.
2) In the downstream of survived buildings more than a middle-rise or higher buildings,
many wood houses avoided being carried away regardless of structural specifications.
3) In the downstream of survived low-rise buildings, or at the location far from survived
middle-rise buildings, only the wood houses with excellent structural specification
avoided being carried away.
4) In the location where there were no survived buildings in the direction of tsunami, there
were some cases that a wood house remained alone. In that case, there were many
examples that some columns or walls were carried away in the direction where tsunami
come.
5) Having metal fastener or not in the column end joints such as the hold down fastener
doesn’t decide whether the house is carried away or remain in.
6) It was possible for the slope land to make lateral force caused by tsunami a little
smaller.

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7.5

Conclusion

This paper classified the damage patterns for different structural categories andbriefly discussed the factors that had caused various types of damage. Based on the
results of the relevant investigation, we are now conducting an additional site
investigation as required and collecting design documents for damaged buildings, whilefurther evaluating the effects of building openings and buoyancy and proceeding withthe elucidation of mechanisms for causing damage and the identification of tsunami
loads on buildings.
* Tsunami Damage Survey Team (The members’ positions as of April 20, 2011)
NILIM (8 members): Isao Nishiyama, Akiyoshi Mukai, Ichiro Minato, Atsuo Fukai,
Shuichi Takeya, Hitomitsu Kikitsu, Hiroshi Arai, and Tomohiko Sakata
BRI (19 members): Juntaro Tsuru, Nobuo Furukawa, Masanori Iiba, Shoichi Ando,
Wataru Gojo, Hiroshi Fukuyama, Yasuo Okuda, Taiki Saito, Bun-ichiro Shibazaki,
Koichi Morita, Hiroto Kato, Tsutomu Hirade, Takashi Hasegawa, Tadashi Ishihara,
Norimitsu Ishii, Yushiro Fujii, Haruhiko Suwada, Yasuhiro Araki, and Toshikazu
Kabeyasawa

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8.
8.1

Damage of Buildings, etc. due to Fire

Objective of Survey

Large number of fires occurred in wide area due to the earthquake and tsunami
brought severe damage to buildings. The entire image of the fires is analyzed in thischapter. Investigation has been conducted in order to grasp the circumstances of the fire
spreading and fire stopping in large city fires and the damage of building fires.
8.1.1

Number of Fire Occurrence

Table 8.1-1 Number of Fires byprefectures

In this earthquake disaster, enormous
tsunami damage occurred, but large number offires were also identified in the areas damaged bytsunami. This is a major feature of fire damage inthis earthquake disaster.
The total 345 fires including non-building
fires reported (as of April 20, 2011) by Fire andDisaster Management Agency (FDMA) of
Ministry of Internal Affairs and Communications(MIC)8.1-1). Table 8.1-1 shows the number of fires
in each prefecture. In Miyagi, more than half ofthe total number of fires were occurred. These345 fires include not only fires occurred in themainshock at 14:46 on March 11, but also ones inaftershocks.
8.1.2

Prefecture
Aomori
Iwate
Miyagi
Akita
Fukushima
Ibaraki
Gunma
Saitama
Chiba
Tokyo
Kanagawa
Shizuoka
Total

Number of Fires
5
26
194
1
11
37
2
13
14
35
6
1
345

(FDMA, as of April 20)

Seismic Intensity and Fire Occurrence

In Japan, the relation between
fire break-out ratio and seismic
intensity will be often discussed inorder to identify the feature ofearthquake fire8.1-2).
The relation between seismic
intensity and fire break-out ratio in
this earthquake are shown in Fig. 8.1-1
and Table 8.1-2. The numbers of fires
in some municipalities without seismic
intensity data are omitted.

4.5Fire per 100,000
population
Fire per 10,000
households

4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
4

5‐

5+

6‐

6+

7

OverallFig. 8.1-1 Relation between fire
break-out ratio and seismic intensity-141-

Table 8.1-2 Seismic intensity, number of fire and fire break-out ratio
Seismic
intensity
4
55+
66+
7
Overall

Population
11,156,088
19,042,953
20,092,544
4,254,959
3,115,586
74,93859,928,945

Number ofhouseholds

Number of fire

4,225,871
8,292,245
8,381,820
1,543,580
1,213,129
23,441
24,482,678

12
31
56
94
126
0
320

Fire per100,000
population
0.108
0.163
0.279
2.209
4.044
0.000
0.534

Fire per10,000households
0.028
0.037
0.067
0.609
1.039
0.000
0.131

And the distribution of seismic intensity, number of fires and municipalities
damaged by tsunami are shown
geographically in Fig. 8.1-2.
Total data of the maximum
seismic intensity by municipalities is
Seismic intensity
based on the reports on seismic
Intensity of 7
Intensity of 6‐upper
intensity released on May 30 and April
Intensity of 6‐lower
25, 2011 by the Japan Metrological
Intensity of 5‐upper
Intensity of 5‐lower
Agency (JMA) of MLIT.
Intensity of 4
Intensity of 3For
thistotaling,
theIntensity of 2
municipalities in which seismic
Under investigation
Municipalities
intensity of the prefectures was 5 lower
damaged by tsunami(5-) or more are included and themunicipalities from this totaling where
seismic intensity has not been obtained
or not yet been investigated are
Number of fires
excluded.
1
5
In only one area where seismic
20
intensity 7 was observed, however, no20
fire is reported. The tendency that the30higher the seismic intensity, the higher
the fire break-out ratio, is observed in
the municipalities where seismic
intensity 6 lower (6-) or less wasrecorded.
In the cases of the 1995
Hyogo-ken Nambu (Kobe) earthquake
and the 2004 Niigata-ken Chuetsu Fig. 8.1-2 Distribution of seismic intensity,
earthquake, in which seismic intensity number of fires and municipalities
7 were recorded, fire ratio per 10,000 damaged by tsunami-142-households is 2~6 cases, but as for the 2011 Tohoku earthquake, the fire break-out ratio
has become lower than the ratio for the 1995 Hyogo-ken Nambu earthquake.
However, in the areas of seismic intensity 6 upper (6+) in 2004 Chuetsu
Earthquake, the ratio is around 0.7. Therefore, for this earthquake, fire break-out ratio of
1.0 in the area of seismic intensity 6 upper is regarded as the same or a little higher
value. The principal reason why the ratio for this earthquake is the same or a little
higher, may be due to that many fires broke out in the damaged area by tsunami.
8.2

Damage by Fire due to Tsunami

There should be a distinction between fire occurred in areas damaged by tsunami(hereinafter referred to “tsunami fire”) and fire occurred in other areas (hereinafterreferred to “earthquake fire”), however at present, detailed information about the fire
scene are not provided. Therefore, this report do not distinguish tsunami fire from
Table 8.2-1 Number and break-out ratio of tsunami fire
Seismic
intensity
4
55+
66+
Not available
Total

Number ofPopulation
households
86,147
207,519
680,002
1,492,701
1,580,722
122,4134,169,504

32,875
73,107
252,323557,650
660,780
45,838
1,622,573

Area of
Number of firetsunami Number per 1km2 area
invasionof tsunami
of fireinvasion
[km2]
14
0
0.000
16.5
3
0.182
44.5
13
0.292
280.5
68
0.242
179
108
0.603
27
21
0.778
561.5
213
0.379

Fire per100,000
population
0.000
1.446
1.912
4.556
6.832
17.155
5.109

Fire per10,000households
0.000
0.410
0.515
1.219
1.634
4.581
1.313

earthquake fire out of the 345 fires.
Therefore, it is assumed the fires reported in the municipalities damaged bytsunami as tsunami fires and the fires
reported in other municipalities as
earthquake fires. The features of each fireon fire occurrence circumstance will bereported. Table 8.2-1 illustrates the list of
number and break-out ratio of tsunami
fire. The data has been acquired bytotaling of the number of fire occurrenceby the municipality areas of tsunami
invasion.
It would be said that the features of
Photo 8.2-1 Tsunami fire at antsunami fire which is reported inelementary school (Ishinomaki city,
damaged area by tsunami, the area of fire
Miyagi prefecture)spread extends to wider area where the-143-debris of buildings etc and automobiles
which drifted and crashed would becomecause of fire and fire spreading route.
Ishinomaki, one of the coastal cities
of Miyagi prefecture, had huge damage
due to tsunami and also had large fire thatspread widely. As for the investigation
soon after the earthquake disaster, thejoint survey team could not find any
information about the initiation of thefire; however, the team identified therange of fire spread.
Photo 8.2-1 shows a fire scene of anelementary school building located atabout 1 km from the coast. Almost all of
the 3-story school building had been
burnt by the flame flared up from cars,
combustible debris and oil and so forththat drifted and accumulated by tsunami
in the schoolyard in front of the building.
Building at a port is one of the mostdamaged buildings by tsunami with not
only tidal wave but also debris, cars andships and so forth drifted by tsunami(Photo 8.2-2 and 8.2-3). Several hundred
automobiles which have been parked in aparking zone, being drifted to a port
warehouse by the tsunami, caused fire atthe place where it accumulated.
The cause of the fire is unclear, but
it is assumed that the car collided severely
each other, the gasoline tank of the cars
were damaged, and sparked bymalfunction of the electrical system by
the seawater. There was no spread of firein the interior of the building, only theexternal wall has been damaged by fire.
Photo 8.2-4 shows the fire at acoastal village after several hours oftsunami invasion. The fire continued for

Photo 8.2-2 Tsunami fire at a port warehouse (Sendai city, Miyagi prefecture)

Photo 8.2-3 Vehicle fire due to tsunami ata parking lot (Iwanuma city, Miyagi
prefecture)

Photo 8.2-4 Fire at a site of 8 buildings
due to tsunami (Noda-village, Iwate
prefecture), Courtesy of Noda-village-144-

over 12 hours. Firefighters could not access to the site because the road had been
destroyed by the tsunami.

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8.3

Damage by Fire due to Earthquake Motion

Concerning the fires
reported in the municipalities
which did not have the damageof tsunami, the feature of fireoccurrence circumstance as anearthquake fire is shown
below.
Major cause of the fire isheatsources
contacting
surrounding combustibles withthe earthquake motion andelectric fires at the recovery of

1.4
1.2

Fire per 100,000
population

1.0

Fire per 10,000
households

0.8
0.6
0.4
0.2
0.0
4

5‐

5+

6‐

6+

7

OverallFig. 8.3-1 Relation between break-out ratio of fire
due to earthquake motion and seismic intensity

Table 8.3-1 Number and break-out ratio of fire due to earthquake motion
Number of Number ofSeismic
Population
households
fireintensity
4
55+
66+
7
Overall

11,069,941
18,835,434
19,412,542
2,762,258
1,534,864
74,93855,881,854

4,192,996
8,219,138
8,129,497
985,930
552,349
23,441
22,905,943

12
28
43
26
18
0
128

Fire per100,000
population
0.108
0.149
0.222
0.941
1.173
0.000
0.229

Fire per10,000households
0.029
0.034
0.053
0.264
0.326
0.000
0.056

power supply from power failure and misuse of the candle which is used for the light inthe midst of blackout nights which werealso seen as past time.
The relation between seismic
intensity and break-out ratio of fire due
to earthquake motion is shown in Fig.
8.3-1 and Table 8.3-1. Mass media havereported intensively fire due to tsunami,
but many fire cases due to earthquake
motion are also identified by this data.
Some building fires are presented in thefollowing.
Photo 8.3-1 shows a house fire Photo 8.3-1 Fire scene of a house (Oushu
scene of one victim in an inland rural city, Iwate prefecture)-146-

district. The fire broke out not soonafter the mainshock but at 10 pm of thesame day. The cause of the fire has notbeen identified clearly, but, it is thought
to be by the spark or hot exhaust gas
leaked from the gap of smoke duct of aboiler for heating and bathing, due toearthquake motions.
Photo 8.3-2 shows a factorybuilding fire in which half of thebuilding burned. The cause of the fire isassumed to be ignition by falling offluorescent light on the ceiling to thefloor where the thinner spilled due toearthquake motions by the mainshock.
Photo 8.3-3 shows another housefire case in which two wooden houses
were completely burnt out and threehouses were partly burnt. The cause offire is assumed to be misuse ofcandlelight for lighting in the midst of
power failure on the night of the next
day of the mainshock.
For a condominium fire, one casehas been investigated: the fire broke out
when electricity supply has been
recovered at the night of the next day ofthe mainshock. The fire broke out on
the 7th floor of a 17-story medium scalecondominium. The residents of theroom of fire origin were absent at thetime, but some neighbors were aware of
the fire and informed the fire station.
Because of early suppression by
firefighters, there was no spread of fireto the upper floor and the next rooms(Photo 8.3-4).

Photo 8.3-2 Fire scene at a factorybuilding (Oushu city, Iwate prefecture)

Photo 8.3-3 Fire scene at a house (Oushu
city, Iwate prefecture)

Photo 8.3-4 Fire scene at a condominium(Sendai city, Miyagi prefecture)-147-

References
8.1-1) FDMA, MIC: http://www.fdma.go.jp/bn/higaihou/pdf/jishin/109.pdf (in Japanese,accessed September 1, 2011)
8.1-2) Editorial Committee for the Report on the Hanshin-Awaji Earthquake Disaster:
Report on the Hanshin-Awaji Earthquake Disaster, Building Series Volume 6, Fire
Damage and Civil Activities, Damage to Information Systems, AIJ, ISBN:
4-8189-2006-1, pp.51, October, 1998 (in Japanese)

-148-

9.
9.1

Response of Seismically Isolated Buildings

Outline of Surveyed Buildings

Miyagi prefecture and nearby areas have experienced disastrous earthquakes
frequently, thus there are many seismically isolated buildings (hereinafter referred to as
SI buildings) constructed in those areas. The Joint Survey Team was dispatched on 1st
and 2nd June, 2011 to observe performance of SI buildings during the earthquake andask persons in charge of the buildings about the damage. In total, 16 SI buildings in
Miyagi prefecture and one SI building in Yamagata prefecture were surveyed. Table
9.1-1 shows the list of SI buildings surveyed.

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Table 9.1-1 List of SI buildings surveyed on 1st and 2nd June, 2011
Usage

Year ofSuper-

Con-

Structure

struction Type

*1

Isolation Device*2

Existence of

JMA Seismic

RecordIntensity at

Displace- Accel- the nearest# of
Floorsmenteration observatory(scratch)*3

A

Office

2009

SRC

9

HRB

○

○

B

Warehouse

1996

S

1

HRB

○

C Condominium

2007

RC

14

NRB, LD, USD

6 lower

D Condominium

2011

RC

12

LRB, USD

6 lower

E Condominium

2009

RC

15

LRB, ESBF Condominium

2009

RC

10

HRB, ESB

6 lowerG

Hospital

2001

RC

6

LRB, ESB

6 lowerH

Office

1999

RC

18

NRB, ESB

I

Hotel

1998

RC

12

NRB, LD, LSD

6 upperJ

Fire station

2006

S

3

LRB, SB, OD

6 upperK

Hospital

2002

RC

5

LRB, NRB, OD

6 upper

L

Fire station

2008

RC

3

LRB, ESB, USD

6 lower○○

6 lower

6 lower○○

6 lower

6 lower to
6 upperM

Hospital

2006

S

6

NRB, NRB+USD, USD,○

5 upper○

5 upper to

ESB
NFire station

2007

RC

3

NRB, ESB, OD

6 lowerO

Hospital

2003

RC

4

NRB, LRB, ESB, LSD

P

Hospital

2000

RC

10

NRB, LD, LSD

Q

Hospital

2002

SRC

4

LRB, SB, OD

6 lower○○

4
5 upper*1

SRC: Steel Reinforced Concrete, RC: Reinforced Concrete, S: Steel*2

NRB: Natural Rubber Bearing, LRB: Lead Rubber Bearing, HRB: High-damping Rubber
Bearing, ESB: Elastic Sliding Bearing, SB: Sliding Bearing, LD: Lead Damper,
USD: U-Shaped Steel Damper, LSD: Loop-Shaped Steel Damper, OD: Oil Damper(Hereinafter referred to as above abbreviations)*3

Newly constructed in 1982 and retrofitted by seismic isolation in 2009.

-150-

9.2 Behavior of Seismically Isolated Buildings
In this section, 5 SI buildings (A, B, C, L and M in Table 9.1-1) are picked up to
describe typical damages and situations under the 2011 Tohoku earthquake (mainly atmainshock).
9.2.1

SI building (A)(1) Building information
The SI building (A) is a steel reinforced concrete office building with 9-story
super-structure and 2-story basement, located in Miyagino ward in Sendai city (Photo9.2-1). The building was retrofitted by using base isolation technique putting isolation
devices on the top of columns in B1F. The floor plan has the 26.4 m × 54 m rectangularshape and 44 HRBs are installed.

(a) Overview of the building(b) Sign board to warn about seismic gap
Photo 9.2-1 SI building (A) – SRC office building –(2) Building performance during the earthquake
Observation results are summarized as follows:a) According to the person in charge of the building, no furniture was turned over andno structural damage was observed.
b) However, some damage was observed at the cover-panels of fire protection and the
expansion joints near the boundary between isolated and non-isolated floors (Photo9.2-2). It seems that parts of expansion joints were not well operated due to the large
displacement of SI floor during the earthquake.
c) The ground surrounding the building partially subsided around 10 cm.

-151-

(a) Damage to the panel(b) Damage to the expansion joint
Photo 9.2-2 Damage near the boundary between isolated and non-isolated floors(3) Earthquake motion records
Accelerometers were installed in this building at B2F, 1F and 9F (top floor). A
scratch board was also installed in B1F to record the displacement of isolation interface.
Furthermore, there is an accelerometer installed by JMA in the basement of an adjacentbuilding. The maximum acceleration values of these accelerometers at the mainshock
are listed in Table 9.2-1.
Table 9.2-1 Maximum acceleration values
Location

Direction
NS [gal]

EW [gal]Vertical Z [gal]Basement ofadjacent building

409.9

317.9

251.4

B2F (below SI)

289.0

250.8

234.9

1F (above SI)

120.5

143.7

373.7

9F

141.7

169.9

523.9

From the trace on the scratch board installed on the SI floor (Photo 9.2-3), themaximum displacement was estimated as around 18 cm at the mainshock on 11 March,2011 and around 10 cm at an aftershock on 7 April, 2011 (Photo 9.2-4).

-152-

NS
EW

Photo 9.2-3 Scratch board installed on the SI floor

NS
NS
EW
5cm

5cm

10cm

EW

10cm

15cm
20cm

15cm
20cm

(a) Trace at the mainshock on 11 Mar. (b) Trace at an aftershock on 7 Apr.
Photo 9.2-4 Trace of displacement of SI floor during earthquake
9.2.2 SI building (B)(1) Building information
The SI building (B) is a one-story steel warehouse constructed in 1996, located in
Miyagino ward in Sendai city (Photo 9.2-5). The building height is 30 m. There are 20
HRBs with diameter 850 mm and 4 HRBs with diameter 800 mm arranged in thebasement with 51.6 m × 31.7 m rectangular shape.

-153-

Photo 9.2-5 SI building (B) – Steel warehouse (2) Building performance during the earthquake
Since the building is located near the Sendai-Shiogama bay, tsunami reached thebuilding and the SI floor was submerged under water. The building also suffered thedamage to outer walls by the collision of floating debris (Photo 9.2-6). Observation
results are summarized as follows:a) According to the person in charge of the building, other warehouses nearby had
trouble of cargo-shift or collapse of stuff by the earthquake. On the contrary, this SI
warehouse had no such trouble at all. Since this warehouse is a freezer, tsunami
water entered in the freezer space was frozen. It took 16 days to remove the waterfrom the SI floor.
b) Tsunami height was estimated ~4.0 m from the trace of water on the wall (Photo
9.2-7) and damage situation of surrounding buildings (Photo 9.2-8). There is no
information about the direction and impact force of tsunami.
c) The ground was excavated in northeast corner of the building around 1.0 m depth,
probably because of the water flow from the building at the moment of tsunami(Photo 9.2-9).
d) From visual inspection, there was no harmful scratch or inflation of the rubber of
HRB, however, severe rust was observed at the steel plates and bolts (Photo9.2-10).

-154-

Photo 9.2-6 Damage due to debris

Photo 9.2-7 Trace of tsunami water

Photo 9.2-8 Tsunami damage tosurrounding buildings

Photo 9.2-9 Excavation of groundPhoto 9.2-10 Rust of High-damping rubber bearing(3) Earthquake motion records
From the trace on the scratch board in the SI floor, the maximum displacement-155-

was estimated as around 21 cm at the mainshock (Photo 9.2-11).

Photo 9.2-11 Trace of displacement of the SI floor on the scratch board
9.2.3 SI building (C)(1) Building information
The SI building (C) is a 14-story reinforced concrete building used for
condominium, located in Miyagino ward in Sendai city (Photo 9.2-12). The building has
U-shaped plan and corners of the building are separated by expansion joints. There are
24 NRBs, 8 LDs and 13 USDs installed in the SI floor.

(a) Overview of the building(b) Sign board to warn about seismic gap
Photo 9.2-12 SI building (C) – RC condominium building –(2) Building performance during the earthquake
Observation results are summarized as follows:a) According to the person in charge of the building, no furniture was turned over andno structural damage was observed inside of rooms. However, the damage to the
expansion joint was observed.
b) Drop of the ceramic tiles on outer wall (Photo 9.2-13) and shear crack on the wall in-156-

the first floor parking space (Photo 9.2-14) were observed. The subsidence ofground ~10 cm was observed around the building.
c) No damage was found to RBs by visual inspection (Photo 9.2-15), however, paint of
USDs was peeled off (Photo 9.2-16) and many cracks were found on LDs (Photo9.2-17).

Photo 9.2-13 Drop of ceramic tiles

Photo 9.2-14 Shear crack on the wall

Photo 9.2-15 Natural rubber bearing

Photo 9.2-16 U-shaped steel damper

Photo 9.2-17 Lead damper and cracks on the surface-157-

9.2.4 SI building (L)(1) Building information
The SI building (L) is a 3-story reinforced concrete building used for fire station,
located in Tome city (Photo 9.2-18). The following SI devices are installed in thebasement with L-shaped plan; 61 m in the east-west direction and 58 m in thenorth-south direction:- 34 LRBs (6 with diameter 650 mm and 28 with diameter 700 mm)- 11 ESBs (6 with diameter 500 mm and 5 with diameter 600 mm)- 8 USDs(a) Overview of the building(b) Sign board to warn about seismic gap
Photo 9.2-18 SI building (L) – RC fire station building –(2) Building performance during the earthquake
Observation results are summarized as follows:a) According to the person in charge of the building, no furniture was turned over andno structural damage was observed.
b) Because of the movement of the SI floor during the earthquake, the bolts of steel
dampers became loose and the paint on the dampers was peeled off widely.
Furthermore, a large amount of residual deformation of steel was remained (Photo9.2-19).
(3) Earthquake motion records
According to the scratch board in the SI floor, the maximum displacement wasestimated as around 40 cm northward (Photo 9.2-20). The displacement was also
confirmed from the trace of scratch found at the expansion joint outside of the building.

-158-

(a) Peeling off of paint(2) Deformation of steel
Photo 9.2-19 Deformation of U-shaped steel damper

S
E

N

W

(a) Around 40 cm northward(b) Around 15 cm eastward
and 22 cm westward
Photo 9.2-20 Trace of displacement of the SI floor on the scratch board

9.2.5 SI building (M)(1) Building information
The SI building (M) is a 6-story steel building with one story basement used for
hospital, located in Ishinomaki city (Photo 9.2-21). Lower part of the building up tosecond story has the 100 m × 100 m square plan and higher part has 100 m × 25 m plan.
The following SI devices are installed in the basement:- 6 NRBs with diameter 1000 mm- 16 NRBs with diameter 1000 mm with USD- 74 ESBs (30 with 400 mm diameter, 25 with 600 mm diameter, 11 with 800 mm
diameter and 8 with 900 mm diameter)-159-

(2) Building performance during the earthquake
Observation results are summarized as follows:a) According to the person in charge of the building, up-down shaking happened
together with horizontal shaking during the earthquake. On the 6th floor, contents
inside of the rooms such as refrigerators and shelves are moved or turned over, andthe fire protection steel door moved to open and hit against the ceiling by verticalshaking causing the damage to the lamp covers. Above the 4th floor, PC monitors
turned over.
b) In the penthouse, anti-vibration rubber of a power generator was moved and thebottom part of a water tank was broken.
c) Because of the movement of the SI floor during the earthquake, the bolts of the steel
dampers became loose and the paint on the dampers was peeled off (Photo 9.2-22).
d) The ground around the building subsided ~20 cm.

(a) Overview of the building(b) Sign board to warn about seismic gap
Photo 9.2-21 SI building (M) – Steel hospital building –(3) Earthquake motion records
From the trace on the scratch board in the SI floor, the maximum displacement
was estimated as around 25 cm westward (Photo 9.2-23). The displacement was also
confirmed from the trace of displacement of the ESB (Photo 9.2-24).

-160-

Photo 9.2-22 Peeling off of paint and loose of the bolts of U-shaped steel dampers

Photo 9.2-23 Trace of displacement of the SI floor on the scratch board

Photo 9.2-24 Trace of displacement of elastic sliding bearing
9.3 Results of Survey
Investigation results of 16 SI buildings in Miyagi prefecture and one SI buildingin Yamagata prefecture are summarized as follows:a) Super-structures of the SI buildings suffered almost no damage even under strong
shaking with JMA intensity 6 upper. It verifies the performance of the SI buildings.
b) There are 8 buildings with scratch boards to measure displacement of the SI floor.

-161-

In most cases, the maximum displacement has been estimated as around 20 cm.
There is one case with the maximum displacement estimated over 40 cm.
c) In some buildings, damage was observed at the expansion joints. It seems that partsof expansion joints were not well operated due to the large displacement of the SI
floor during the earthquake.
d) Subsidence of ground around the building was observed in some buildings.
e) Many cracks were found in lead dampers. A number of cracks might be increased
by aftershocks.
f) Peeling off of paint was observed widely for U-shaped steel dampers. In some cases,
residual deformation of steel was remained.

-162-

10. Concluding Remarks
Although more than five months have passed after the earthquake occurred,approximately 90,000 evacuees still live in difficulties and whole damage of the disastercannot be captured. These facts make us realize that the disaster was unprecedented
huge one. It was also the first experience for us that the investigation areas needed to belimited considering the influence of the accident in the Fukushima-dai-ichi nuclear
power plant and that we had to be concerned with the safety of staff members against
large aftershocks including large ones.
This report summarized the survey results described in our quick report alreadypublished in Japanese with some additional survey results on the seismically isolatedbuildings. The outline of each chapter is as follows;
The first chapter forms “Introduction” to briefly figure how NILIM and BRI
cooperated to prepare the system (The Joint Survey Team on building damage) in orderto respond to the support requests of affected areas and how the team conducted various
surveys and researches after occurrence of the earthquake.
The second chapter titled "Outline of Research and Field Survey" describes theoutline of the researches and field surveys and the names of the staff members who
were in charge of the works.
The third chapter titled as “Overview of Damage” reviews outline of the 2011
Tohoku earthquake, applied situation of enforcement of the laws related to disastermanagement, data on human and physical damage and situation of provision of
temporary houses etc. mainly based on the officially announced data as of April 20
when this report was summarized (if new data becomes available, this report uses
updated data indicating new date).
The fourth chapter, “Outline of Earthquake and Tsunami”, provides research
results on earthquake source, models of tsunami source and maximum height of tsunami
and so on. .
The fifth chapter describes “Earthquake Motion Observation and Results” that
includes characteristics of earthquake records from BRI strong motion observation
network etc. It is noteworthy that the data of above-mentioned BRI earthquake data wasreferred globally as the first seismic data of the earthquake, since the data network
system of the National Research Institute for Earth Science and Disaster Prevention(NIED) that was usually one of the first data resource from earthquake did not work
well because damage to network facilities had occurred immediately after theearthquake.

-163-

The sixth chapter titled “Damage to Buildings by Earthquake Motions”
summarizes the policy of the investigation and the results of damage surveys on wood,steel frame, and reinforced concrete structures, residential land, foundation andnon-structural elements. The results are summarized as follows.
1) Wood houses: The damage of upper structure were observed in several areas
however the damage to wood houses seems not so heavy as an impression in Kurihara
city where seismic intensity 7 was recorded. Many damage of structure were observed
due to deformation of developed residential land in Sendai city, Miyagi prefecture andYaita city, Tochigi prefecture. The damage to roof tiles could be more observed in both
Fukushima and Ibaraki prefectures than in Miyagi prefecture where major earthquakes
frequently occurred since the 1978 Miyagi-ken-oki Earthquake. The damage types are
similar to those of the past earthquakes.
2) Steel frame structures: There was almost no damage to main steel structure
members such as columns and beams. Damage of vertical braces’ rupture etc. wereobserved in the school gymnasium that was constructed in the years of old seismic code
(before 1981) however the damage ratio is smaller than the case of the 2004 Niigata-ken
Chuetsu Earthquake. On the other hand, damage to non-structural elements including
falling of ceilings were observed comparatively more than the past cases.
3) Reinforced concrete structures: Most of structural damage to reinforced concrete
structure was observed in the buildings designed with the previous seismic code. The
number of damaged reinforced concrete buildings is not so large as considered with theseismic intensity observed nearby. The damage types were mostly similar to the past
seismic damages that include severe damage such as loss of axial force bearing capacity
due to shear failure of columns.
4) Residential land, Foundation: Liquefaction occurred in so wide areas that could
not be seen during the past earthquakes in Japan. Research on the mechanism andconsiderations of counter-measures will be necessary not only for individual buildings
but also for infrastructure like roadway structures, water supply and sewage systems. In
some residential lands, heavy damage such as ground failure was observed similar tothe damaging earthquakes in the past.
5) Damage to non-structural elements of buildings of comparatively old
construction types were confirmed in many cases. In addition, break and falling of
non-structural elements at rather higher parts were also confirmed.
The seventh chapter describes “Damage to Buildings etc. in Inundation Areas due
to Tsunami” that includes research on the existing guidelines regarding the building
design methodologies against tsunami. This chapter introduces conducted surveys on
remaining, collapsed or washed away buildings in the major tsunami affected areasfrom the north in Yamada town, Iwate prefecture to the south in Yamamoto town,
Miyagi prefecture. The surveys included measuring damage of buildings, depth of-164-

tsunami and structural element data for calculating horizontal load bearing capacity andother values. After verification of existing guidelines, a proposal was prepared in orderto make the guidelines more rationalized ones.
The eighth chapter on “Damage of Buildings, etc. due to Fire” summarizes resultsof field surveys on fires in tsunami affected areas and shake-induced fires in other areasand clarifies the features of damage. The result shows that many usual type of fires due
to earthquake happened even though fires in tsunami affected areas are noticed andreported more.
The ninth chapter summarizes “Response of Seismically Isolated Building”
including outline of surveyed buildings and the behavior of seismically isolatedbuildings.
The damage surveys in this report were conducted as carefully as possible, using
around 200 person-days (130 persons). However, whole damage of the earthquake may
not be covered, considering the damage of wide areas. Further surveys will be
continuously carried out.
Recovery and rehabilitation of the affected areas have advanced slowly but steadily,
while the introduction (Section 1) of this report says that whole damage cannot be
grasped yet. The government set up the Reconstruction Design Council on April 11,
which submitted its report of recommendation in June, 2011. The MLIT also establishedvarious working committees. In the field of buildings, the Building Structural CodeCommittee (chaired by Prof. Tetsuo Kubo, the University of Tokyo) that aims to review
draft structural code of buildings in the NILIM, is analyzing the damages and promote
related technical reviews and so on in cooperation with BRI in order to secure the safetyof buildings based on damages caused by the Great East Japan Earthquake.
NILIM and BRI would like to contribute to the society through this report and theadvanced technical knowledge. It will be very much appreciated if related organizations
and individuals will cooperate with us continuously in the future.
Lastly, NILIM and BRI would express deepest condolence to the victims of thetsunami and earthquake and their family members as well as sufferers affected from thedisaster. In addition, we would like to express our heartfelt appreciation to people fromaround the world for their warm support and cordial friendship.
Note 1: A comment via e-mail sent from U.S.A. dated on March 17,“I learned that the NIED servers were out, so the shaking must have been pretty bad. I was able tosee the BRI ground motions and some reports on buildings. Very good and quick work”-165-

TECHNICAL NOTE of NILIM
No. 647
September 2011
BRI Research Paper
No. 150
September 2011
© National Institute for Land and Infrastructure Management© Building Research InstituteNational Institute for Land and Infrastructure Management
Ministry of Land, Infrastructure, Transport and Tourism
1, Asahi, Tsukuba, Ibaraki, 305-0804 Japan
Phone:+81-(0)29-864-2675
Building Research Institute (BRI)
Incorporated Administrative Agency
1, Tachihara, Tsukuba, Ibaraki, 305-0802 Japan
Phone:+81-(0)29-864-2151-166-