Proceedings of the International Symposium on Engineering Lessons Learned fromthe 2011 Great East Japan Earthquake, March 1-4, 2012, Tokyo, JapanTHE DAMAGE OF SEWAGE TREATMENT SYSTEMSCAUSED BY THE GREAT EAST JAPAN
EARTHQUAKEManabu MATSUHASHI1, Wataru FUKATANI2, Toshihiro YOKOTA3, Masaaki OZAKI4, andNobuyuki HORIE5
1

Research Engineer, Department of Water Quality Control, National Institute for Land andInfrastructure Management, (NILIM), Ministry of Land, Infrastructure, Transport and Tourism (MLIT),
Tsukuba, Japan, matsuhashi-m92ta@nilim.go.jp
2
Senior Researcher, Department of Water Quality Control, NILIM, MLIT, Tsukuba, Japan,
fukatani-w86xr@nilim.go.jp
3
Head, Department of Water Quality Control, NILIM, MLIT, Tsukuba, Japan,
yokota-t92tc@nilim.go.jp
4Research Coordinator, Department of Water Quality Control, NILIM, MLIT, Tsukuba, Japan,
ozaki-m92ta@nilim.go.jp
5Research Director, Department of Water Quality Control, NILIM, MLIT, Tsukuba, Japan,
horie-n92tb@nilim.go.jp

ABSTRACT: The Great East Japan Earthquake severely damaged sewage treatment
systems over a wide area from the Tohoku Region to the Kanto Region. At the many
sewage treatments, the systems were shut down by the tsunami, numerous building
structures were toppled by the wave force of the tsunami and electrical and mechanicalmachines were damaged by submersion. The many pipelines damaged by liquefaction
throughout the region lost their ability to carry sewage as a result of plugging by sandafter the occurrence of the earthquake.
Key Words: Great East Japan Earthquake, tsunami, liquefaction, sewage treatment
systems, sewage systems, and pipes

INTRODUCTION
At 2:46 p.m. on March 11, 2011, an earthquake with magnitude of 9.0 (seismic intensity of 7 at
Kurihara City in Miyagi Prefecture), which was the most powerful earthquake ever observed in Japan,
occurred with its hypocenter offshore from the Sanriku Coast (below referred to as, “Great East Japan
Earthquake”). This disastrous earthquake claimed many precious human lives and property at the sametime as it shut down urban and industrial activities by, for example, disrupting transportation networks
and cutting off communications, severely impacting Japan socially and economically. And public
infrastructures which must support and protect the life of the people were also severely damaged at thesame time as questions were raised about how such infrastructure should be provided in the future.
Sewage treatment systems, which are important infrastructure, also suffered serious damage,forcing the lengthy shut down of sewage treatment services. Japan, which is known as an

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“Archipelago of Disasters”, has been struck by many massive earthquakes in recent years, but two
new phenomena caused by the Great East Japan Earthquake are considered to be characteristics ofdamage to sewage treatment systems.
One is catastrophic damage to sewage treatment systems caused by tsunami. Sewage treatment
plants and pumping stations located along the coastlines of the prefectures of Iwate, Miyagi, andFukushima which were struck by giant tsunami lost their sewage treatment functions because theirelectrical and mechanical equipment malfunctioned as a result of submersion, and their civilengineering structures were destroyed by powerful wave forces. It has been estimated that it will takemore than one year to restore these severely damaged treatment plants.
The other characteristic is that widespread severe liquefaction occurred in the Kanto, which is far
from the hypocenter. Every day, news broadcasts and newspapers reported leaning power poles,
settlement of homes, and waves on road surfaces severely obstructing not only vehicle traffic, butpedestrian use. Damage of these kinds was seen frequently in regions where the land had been
artificially improved. In Urayasu City, liquefied soil flowed into pipelines, plugging them andpreventing their use as part of the sewage treatment systems for long periods of 1 to 2 months. Somemanholes were uplifted more than 1m or displaced sideways, and in Itako City, buried pipes appeared
above the ground.
In Japan, this “Archipelago of Disasters”, it is still necessary to take advance measures to increase
earthquake resistance in preparation for disasters. On the other hand, many challenges remain to be
overcome to implement disaster countermeasures. For example, responding to the rapidly changing
global environment, preparing for earthquakes exceeding the scale previously hypothesized, andovercoming the financial challenges caused by the recent deterioration of the finances of the national
government and of regional governments.
It is said that sewage treatment systems are irreplaceable facilities. To this extent, adequate
measures to prepare for disasters must be taken promptly. We also have to devote all our resources toquickly building sewage treatment systems capable of responding to future disasters such as thepredicted Tokai-Nankai Earthquake.
This paper reports on the damage to sewage treatment systems by the Great East Japan Earthquake,the response of the Ministry of Land, Infrastructure, Transport and Tourism, and its approach to futureearthquake resistance measures.

STATE OF DAMAGE TO SEWAGE TREATMENT SYSTEMS
Damage to sewage treatment systems
Sewage treatment systems generally use the natural flow method, so treatment plants areconstructed on low-lying ground near a public body of water. Therefore, in cities along the Pacific
Ocean coastline, treatment plants have been unavoidably constructed at relatively low places along thecoast, where they were directly impacted by the tsunami damage. In the area inundated by the tsunami,
electrical equipment and machines were destroyed. And at sewage treatment plants not isolated fromthe coastline by structures or other obstructions, the destruction of civil engineering structures bypowerful wave forces, and other unprecedented severe damage to sewage treatment systems occurred.
Distribution of damaged sewage treatment plants
Table 1 shows the state of damage to sewage treatment plants immediately after the Great East
Japan Earthquake (March 16, 2011) and the present time (January 10, 2012). The Ministry of Land,
Infrastructure, Transport and Tourism clarified and categorized information about damage to sewage
treatment systems at one-week intervals beginning immediately after the earthquake. According to
information provided two days after the earthquake, damage occurred at a total of 120 sewage
treatment plants; 44 sewage treatment plants were shut down, facilities at 67 treatment plants werepartially damaged, and the state of damage is unclear at 9 treatment plants.
As shown in Figure 1, damage has been confirmed over a wide area ranging from Iwate Prefecture
to Kanagawa Prefecture, with sewage treatment plants along the coastlines of the prefectures of Iwate,1497

Miyagi, and Fukushima suffering particularly severe tsunami damage, while even at inland sewage
treatment plants which were spared tsunami damage, the earthquake motion either damaged or
dislodged sludge scrapers.
Now that ten months have passed since the earthquake (Jan. 10, 2012), at 95 inland sewage
treatment plants, normal treatment has been almost completely restored by early earthquake response,
but at 15 treatment plants damaged by tsunami, simple treatment is now performed by primary
treatment and chlorine sterilization as full-scale restoration activities continue.
Table 1. State of Damage to Sewage Treatment Systems Immediately After the Earthquake and at the
Present Time
March 16, 2011

January 10, 2012

Number of damaged treatment plants

120

120

Operation shut down*

44

15

Facility damaged※

67

96

Unclear (Nuclear plant area)*Includes simple treatment

99※Includes almost all normal treatment

Operation shut down
Facility damaged
UnclearFigure 1. Damage to Sewage Treatment Systems by the Great East Japan Earthquake

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Causes and characteristics of damage to sewage treatment plants
In order to clarify the causes of various kinds of damage at sewage treatment plants, aquestionnaire survey (effective response rate: 69%) was carried out at local governments in regions
where damage occurred.
The percentages of damage by cause of damage at individual facilities inside sewage treatment
plants (divided into 23 facilities) (Fig. 2), were 54% caused by tsunami, followed by 41% byearthquake motion, and 4% by liquefaction.
Damage to sewage treatment systems caused by earthquake motion included derailment or
breakage of flight chains and breakage of flight plates of sludge scrapers, or leakage caused bydisplacement of expansion joints of interior pipes, etc. (Fig. 3). But these kinds of damage were also
caused by past earthquakes, and at the same time, at many damaged sewage treatment plants,
countermeasures hypothesized on level 2 earthquake motion have not yet been taken, so it is predictedthat similar damage will gradually decline in severity as earthquake resistance measures progress.
Damage caused by tsunami can be broadly categorized as two kinds: damage caused by the wave
force of tsunami and damage caused by submersion.
It is reported that damage caused by the wave force of tsunami varied in its degree according to
the distance from the coast and according to the layout of structures between the coast and thedamaged facility *1, but as shown in Figure 4 and Figure 5, on civil engineering structures andbuildings inside treatment plants at locations without structures acting as barriers, damage such as thedestruction of gates, windows, walls, or columns occurred often.
Submersion damage caused by tsunami occurred throughout the prefectures of Iwate, Miyagi,
Fukushima, and Ibaraki. According to the results of the questionnaire survey, at some treatment plants,
respondents answered that the maximum submersion depth (maximum traces of maximum submersion
on each facility) was 10m or more, making this the most common cause of damage to sewage
treatment plants by the Great East Japan Earthquake. Specific damage by submersion was, as shownby Figure 6, shutting down functions of electrical equipment and machines, deterioration of insulation,
power failures or short-circuits, and the partial or complete halting of sewage treatment functions. In
addition, large quantities of floating debris (rubble, automobiles, etc.) flowed into reaction tanks,
creating conditions obstructing restoration.

1%
54%

Earthquake motion

41%
4%

Liquefaction
TsunamiOthers(power failure etc.)

Figure 2. Causes of Damage to Sewage Treatment Plants

Figure 3. Earthquake Motion Damage to Sewage Treatment Plants (Leaks, flight panel displacement)1499

Figure 4. State of Damage to Walls and Columns of Structures by Wave Force

Figure 5. Damage to Doors and Windows by Wave Force

Figure 6. Damage to Electrical and Mechanical Equipment by Submersion

Restoration of sewage treatment functions
Figure 7 shows change over time of the number of sewage treatment plants which were shut down.
At the time of the disaster, 48 sewage treatment plants were shut down (tsunami was the cause at 20 ofthese).
At treatment plants shut down by earthquake motion, normal operation was almost entirely
restored by about half a month after the earthquake by prompt emergency restoration.
However, at 20 sewage treatment plants damaged by tsunami, while restoration activities were
obstructed by fatal damage to entire facilities and by rubble etc., in order to prevent untreated waterfrom flowing into city streets and conserve public waters, beginning about three and one-half months

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Number of plants where theoperation was shut down by tsunami

Jan. 10

Dec. 21

Dec. 1

Nov. 11

Oct. 22

Oct. 2

Sept. 12

Date

Aug. 23

Aug. 3

July 14June 24

June 4

May 15

April 25

April 5

Number of locations whereoperation was shut down

March 16

Number of locations in sewage treatment plants

after the earthquake, the plants began to perform simple treatment such as precipitation or sterilization,and on January 12 this year, emergency restoration work has been completed at all sewage treatment
plants receiving inflowing polluted water. But it is predicted that it will take about two years to returnthese plants to normal operation, and it is believed necessary to take tsunami-resistance measures at
sewage treatment facilities in the future.
The tsunami severely damaged many sewage treatment plants, but the sewage treatment functionof a number of treatment plants has been quickly restored. So a survey was performed to learn thereasons why the functions of some sewage treatment plants could be restored rapidly. The present
survey clarified characteristics such as installing concrete covers on reaction tanks and placing thecontrol rooms used to control electrical and mechanical equipment on the second or higher floor of thebuilding. For these reasons, future surveys will be carried out to obtain reference information to be
applied to plan tsunami measures for future sewage treatment plants.

Figure 7. Change Over Time of the State of Operation of Treatment Plants by Cause of Damage

Damage to sewer mains and manholes
It has been reported that beginning with the Niigata Earthquake (1964), which increased people’sfamiliarity with the word, “liquefaction phenomenon”, the Hanshin-Awaji Earthquake, Kushiro
Offshore Earthquake, and the more recent Niigata Prefecture Chuetsu Earthquake and the Noto
Peninsula Earthquake, triggered liquefaction which damaged sewage treatment system pipes andfacilities at the same time as it uplifted manholes high above road surfaces, obstructing the passage of
automobiles.
Table 2 compares damage to sewage pipelines and facilities by the Great East Japan Earthquakewith damage by past earthquakes (Noto Peninsula Earthquake and Niigata Chuetsu Earthquake).
The characteristics of earthquakes and characteristics of the ground differ so they cannot becorrectly compared, but the total damaged length by this earthquake is about 10 times that of the
Niigata Chuetsu Earthquake, which was marked by long damaged length. And because of thewidespread damage by the Great East Japan Earthquake, the number of damaged organizations was
also more than 50 times as large as that of past earthquakes. And when the damaged length was
divided by the number of damaged organizations to compare this with past earthquake damage by
regional governments, the values obtained showed that in addition to the prefectures of Miyagi,
Fukushima, and Ibaraki, which are close to the hypocenter, an extremely high value was obtained for
Chiba Prefecture where the shaking was relatively low.

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Table 2. Lengths of Damage to Sewage Treatment Pipeline Systems by the Great East Japan Earthquake
and Past Earthquakes

Prefecture Name

Number of
DamagedGroupsDamage Length/total
lengthAomori1

0.1㎞/113㎞

0.1％

0.1km

Iwate

11

12㎞/3526㎞

0.3％

1.1km

Miyagi39

221㎞/9702㎞

2.3％

5.7km

Fukushima22

120㎞/5110㎞

2.3％

5.5km

Ibaraki36

129㎞/9509㎞

1.4％

3.5km

Tochigi

2

1㎞/266㎞

0.4％

0.5km

Saitama

10.006㎞/214㎞

0.003％

0.006kmChiba

13

54㎞/8446㎞

0.6％

4.2km

Kanagawa

1

0.5㎞/11625㎞

0.004％

0.5km

Tokyo

1

12㎞/15793㎞

0.1％

12km

Niigata
Great East Japan
Earthquake
Noto Peninsula
Earthquake
Niigata-ken Chuetsu
Offshore Earthquake2

1㎞/426㎞

0.2％

0.5km

129

550㎞/64730㎞

0.8％

4.3km

6

15㎞/652㎞

2.3％

0.4km

5

50㎞/3072㎞

1.6％

10km

DamageDamage length
rate/number of Groups

Distribution of damage to sewer pipes and manholes
Because damage to sewer pipes etc. was widespread, in order to clarify the characteristic of theforms of the damage regionally, a questionnaire survey of regional governments in damaged regions
was carried out.
The survey organized the distribution of damaged locations by categorizing the form of damage asa), b), and c) below.
Manhole uplifted

Paving damaged

Sewer pipe uplifted

Manhole body displaced/broken

House, power pole,etc. settled or inclined

Manhole body
displaced/broken

Sewer pipe broken

Incorrect slope of sewer pipe

Sewer pipe plugged by sand
Lateral pipe protrusion
Sewer pipe saga）Liquefaction of backfill

Sewer pipe pulled out

Sewer pipe sagb）Blanket liquefaction ofsurrounding ground

Road surface settled

Road surface settled

Sand boiling sediment

Road surface settled

Sewer pipe pulled out

Retaining wall toppled
or deformed

Amplification of
shaking caused
deformation at
earthworkboundaryC）Liquefaction of surrounding groundaccompanied by lateral flow
Damage to sewage
treatment systems

Damage outside sewage
treatment systems

Figure 8. Categorization of Causes of Damage to Sewage Treatment Systems

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a) Liquefaction of backfill
Case where only the backfill of sewer pipe facilities liquefied (a in Fig. 8)b) Blanket liquefaction of the surrounding ground
Case where the surrounding ground entirely including the backfill liquefied (b in Fig. 8)c) Deformation of the surrounding ground accompanied by lateral flow
Case where lateral flow was caused by liquefaction etc., including the surrounding ground (c inFig. 8).
Figure 9 is a diagram showing the distribution of the causes of damage to sewer pipes.
It shows that damage to backfill by liquefaction was seen relatively often in the Tohoku Region,
which includes the prefectures of Iwate, Miyagi, and Fukushima, and damage caused by liquefactionof all the surrounding ground was seen in Tokyo, Chiba Prefecture, Ibaraki Prefecture and otherregions centered on the Kanto, which are far from the hypocenter and where the earthquake motion
was smaller than in Tohoku.
And although not shown in the figure, in hilly regions of Sendai City and Shiroishi City in Miyagi
Prefecture, or in Fukushima City in Fukushima Prefecture, liquefaction of the surrounding groundoccurred accompanying large-scale lateral flow.
Iwate Prefecture
埋戻し土の液状化
Liquefactionof backfill
Liquefaction of
周辺地盤の液状化
surrounding ground
Liquefaction of backfill and
埋戻し土及び周辺地盤の液状化
surrounding ground
Damage other thanliquefaction
Damage by unknown cause
No answer

Niigata Prefecture

Miyagi Prefecture

Fukushima No. 1 Power Plant
Fukushima Prefecture
Tochigi Prefecture
Ibaraki Prefecture
Saitama PrefectureTokyo
Miyagi Prefecture

Figure 9. Distribution of Damage to Sewer Pipes
Damage to sewer pipes and manholes and its characteristics(a) Damage to backfill caused by liquefaction and its characteristics
In the Tohoku Region close to the hypocenter, much of the liquefaction of backfill upliftedmanholes above the ground or deformed the road surface at locations of pipeline backfill, which aretypes of damage similar to those caused by the past Niigata Prefecture Chuetsu Earthquake or the Noto
Peninsula Earthquake. (Fig. 10) But on most of the damaged sewer pipes and manholes, earthquake
resistance work had not been executed. And sewer pipes constructed by an execution method
stipulated in present earthquake resistance design guidelines satisfied earthquake resistance
performance although they were slightly damaged, so it is assumed that future strengthening of theearthquake resistance of sewer pipes and manholes will mitigate such damage.

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From Murata-machi
Town web site

From Osaki City
web site

From Tome
City web site

From Zao-machi
Town web site

From a Sendai
City document

From Shiroishi
City web site

From the Marumori-machi
Town web site

Figure 10. State of Damage to Sewage Treatment Pipeline Systems Caused by Liquefaction of Backfill
in Miyagi Prefecture(b) Damage caused by blanket liquefaction of the surrounding groundThe blanket liquefaction of the surrounding ground which was concentrated on the shore of Tokyo
Bay and in the lower basin of the Tone River, which are far from the hypocenter, severely damaged
road and houses etc. in addition to sewage treatment systems. Damage to sewage treatment systems
was primarily meandering and sagging of sewer pipes, displacement of manhole bodies, and plugging
by sand, etc., and cases where part of a sewer pipe was exposed above the ground surface wasconfirmed. (Fig. 11)
The causes of such large-scale liquefaction are believed to be the long duration of the earthquake
motion, even where this motion was smaller than in the Tohoku Region, and the continuous
occurrence of large after-shocks and induced earthquakes *3. Typical locations where these phenomena
occurred were concentrated in Chiba Prefecture and Ibaraki Prefecture.
The districts shown in Table 3 share a common history: filling of seashores, old river courses, andmarshes etc. to prepare land for residences or roads. In Urayasu City, where damage was particularly
conspicuous, large scale seashore land reclamation was executed between the early 1970s and theearly 1980s, but in the Imagawa District and Irifune District where the landfill was completed
relatively early, main sewer pipes breaking or pulling out, displacement of manhole bodies and similar
damage occurred at many locations. Because it was land reclaimed from the ocean and the layer above
the engineering reference elevations of T.P. -40 to -50, was formed by loose sandy ground, its N-value
was low, and according to location, ground improvement had been done by pre-loading as a soft
ground countermeasure or sand compaction pile work as a liquefaction prevention measure, and it isassumed that the degree of damage varied greatly according to the landfill period, whether or not
ground was improved, and the improvement method. The characteristics of the damage must be
analyzed in detail to help hypothesize future damage, select countermeasure technologies.

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Figure 11. Blanket Liquefaction Damage of Surrounding Ground (Sand plugging, sewer pipe exposure)

Ibaraki Prefecture

Chiba Prefecture

Table 3. Typical Locations of Large-scale Liquefaction
Name of local
government

District nameLand
condition

Land use

Chiba City

Kaihin‐makuhari

Beach

Housing land Main sewer – lateral pipe connection(reclaimed) damaged, plugged by sandUrayasu City

Imagawa

Beach

Abiko City

Fusa

Flood plain

Narashino
City
Shimotsuma
City

Kasumi

Beach

Kinu

Old rivercourseHousing land Manhole side soil mass displaced, plugged by(reclaimed) sand, road surface collapsed
Housing land Plugged by sand, sewer pipe sag(reclaimed)
Housing land Sewer pipe damaged, manhole damaged(reclaimed)
Housing land Manhole side soil mass displaced, manhole(reclaimed) damaged, road surface collapsed

Inashiki City

Nishishiro

Delta

Itako City

HinodeDelta

Kamisu City

Horiwari

Marsh

Typical damage

Housing land Sewer pipe pulled out(reclaimed)
Housing land Sewer pipe uplifted (exposed above ground),(reclaimed) blocked by sand
Housing land Uplifting or opening of joints of storm drain,(reclaimed) road surface collapsed（Based on results of on-site survey and interview survey by the NILIM）(C) Damage caused by deformation of the surrounding ground accompanied by lateral flow
In Aoba Ward and Taihaku Ward of Sendai City in Miyagi Prefecture and in Fukushima City etc.
*2, ground was deformed by lateral flow caused by liquefaction of the surrounding ground, causing
damage such as meandering or pulling out of sewer pipes and breakage of sewer pipes. Damage by
past earthquakes included localized lateral flow around seawalls and on prepared embankments, but atmany places, the Great East Japan Earthquake caused large-scale ground deformation—fluidization ofentire regions which had been artificially filled by embanking etc., a type of damage caused at somelocations by the Hanshin-Awaji Earthquake.
Their causes will be studied by a future comparison of geological conditions, the bedrock surface,histories of past land preparation, and sewer pipe damage and other surrounding structural damage.

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EFFORTS TAKEN TO RESTORE SEWAGE TREATMENT SYSTEMSOn April 12, the Sewerage and Wastewater Management Department, Water and Disaster
Management Bureau, Ministry of Land, Infrastructure, Transport and Tourism, established the Sewage
Treatment System Earthquake/Tsunami Countermeasure Technology Study Committee (Chairman:
Professor Hamada Masanori of Waseda University) consisting of scholars etc., in cooperation with theJapan Sewage Works Association in order to carry out appropriate emergency restoration of sewage
treatment facilities damaged by the Great East Japan Earthquake and to perform final restoration toprevent repeat damage.
The committee released the Emergency Technical Recommendations to Restore Sewage Treatment
Systems (April 15), the Second Recommendation, Staged Emergency Restoration Methods (June 14),and the Third Recommendation, Final Restoration Methods for Sewage Treatment Systems Damagedby the Great East Japan Earthquake (August 15). These sequentially presented the current state ofrevised guidelines concerning the sewage treatment system BCP method, and methods of support
during disasters. It is expected that based on these recommendations, efforts to carry out final
restoration in the disaster regions will be accelerated.
Regional governments in regions where damage occurred presented their basic opinions on how to
improve the level of treatment in stages through emergency restoration according to the time periods
required until final restoration under the second recommendation, carried out staged emergency
restoration while ensuring the quality of the discharged water in line with the basic opinions, and in
response to the third recommendation, rapidly carried out restoration by presenting restoration
methods permitting the adequate implementation of measures, not only to restore functions, but toprevent recurrence of damage.
To resolve problems with the post-earthquake response by sewage treatment system managers, thecommittee has presented a BCP procedure which considers the dominance of post-earthquake
response based on the preparation of BCP and of tsunami etc., and a revision of the BCP manual basedon this procedure is scheduled to be done in the future.
The NILIM is, as the secretariat of the committee, responsible for analysis of causes of the damage
and for technological studies of restoration methods etc. It is scheduled to study sewage treatment
system BCP and wide area support during disasters, and will continue to offer technical support.

CONCLUSIONSIn the future, efforts must be made to encourage earthquake resistance measures and tsunami
protection measures for sewage treatment facilities. The following are concrete descriptions of such
efforts.
First, based on lessons taught by the Great East Japan Earthquake and the recommendations of the
Sewage Treatment System Earthquake/Tsunami Countermeasure Technology Study Committee, apressing challenge is to conduct further damage analyses and studies of technological measures toestablish required performance standards. And in particular, to deal with predicted large earthquakes in
the maximum South Pacific Trough class *4, technological response measures must be quickly andconcretely proposed in order that measures for cities where damage is predicted be taken as quickly as
possible.
The second is to establish countermeasure methods to reduce damage and to promote their wide
introduction. Following the Great East Japan Earthquake, sanitary problems caused by polluted water
overflowing into living environments and into public bodies of water attracted attention, so the needfor sewage treatment system BCP was pointed out. It has been revealed that an effective way torapidly collect damage information after an earthquake and to efficiently carry out emergency
restoration is to introduce asset management. A large amount of knowledge has been obtained
concerning effective ways to provide support during a wide-area disaster encompassing many cities.
In the future, it will be necessary to resolve disputes and technological challenges in order toaggressively enact sewage treatment system BCP measures and introduce asset management, and at1506

the same time, carry out simulations and training, etc. in order to be able to rapidly build a disastersupport system to deal with wide-area disasters.

ACKNOWLEDGMENTS
We would like to thank members of the following local governments for their cooperation with thefield survey, hosting meetings, and the provision of photographs, Iwate Prefecture, Miyagi Prefecture,
Sendai City, and Itako City.

REFERENCES*1

Supplementary opinions concerning methods of designing buildings with structural strength
ensuring safety from tsunami, November 17, 2011, Ministry of Land, Infrastructure, Transport andTourism, Housing Bureau, In Japanese.
*2
Kamai, T. (2011). “Slope damage caused by the Great East Japan Earthquake of 2011-Primarily
slope damage in urban regions.” Chishitsu to Chosa (Geology and Surveying), Vol. 130, 28-33, In
Japanese*3
Fourth Report of the Sewage Treatment System Earthquake/Tsunami Countermeasure Technology
Study Committee, October 17, 2011, (Sewerage and Wastewater Management Department, Water
and Disaster Management Bureau, Ministry of Land, Infrastructure, Transport and Tourism) , In
Japanese*4Interim Summary by the Nankai Trough Giant Earthquake Model Study Committee,
December 27, 2011, Cabinet Office, Nankai Trough Giant Earthquake Model Study
Committee, In Japanese1507