Proceedings of the International Symposium on Engineering Lessons Learned fromthe 2011 Great East Japan Earthquake, March 1-4, 2012, Tokyo, JapanRESIDENTIAL DAMAGE IN IBARAKI DURING THE
GREAT EASTERN JAPAN EARTHQUAKE
Kazuya YASUHARA1, Makoto TAMURA2, Yu TABAYASHI3, Satoshi MURAKAMI4 and Hirotaka
NAKAJIMA5
1

Professor Emeritus, Institute for Global Change Adaptation Science (ICAS), Ibaraki University, Mito,Ibaraki, 310-8512, Japan, yasuhara@mx.ibaraki.ac.jp
2
Associate Professor, Institute for Global Change Adaptation Science (ICAS), Ibaraki University,Mito, Ibaraki, 310-8512, Japan, tamura@mx.ibaraki.ac.jp
3
Researcher, Institute for Global Change Adaptation Science (ICAS), Ibaraki University, Mito, Ibaraki,
310-8512, Japan, yutabay@mx.ibaraki.ac.jp
4
Associate Professor, Department of Urban and Civil Engineering, Ibaraki University, Hitachi, Ibaraki,
316-8511, Japan, Murakami@mx.ibaraki.ac.jp
5Engineer, NPO GIS Research Institute in Ibaraki, Shinoyama, Jyousou, Ibaraki, 300-2721, Japan,
hirotaka@nsc30th.co.jp
ABSTRACT: Damage in Ibaraki from the tsunami and liquefaction during the 3.11
earthquake was remarkable from a historical perspective. Regarding two issues, thisstudy specifically examines the characteristics of damage to residential areas fromtsunami and liquefaction. GIS-aided analysis reveals that tsunami-induced damage
extends throughout coastal areas from north to south while liquefaction-induced damage
is concentrated in southern areas. Future disaster reduction planning should beundertaken based on the results of analysis presented herein.
Key Words: Great Eastern Japan Earthquake, Ibaraki, Residence, Tsunami, Liquefaction,GIS, City planning

INTRODUCTION

Little attention has been devoted by mass media to the damage triggered by the 3.11 Eastern Japan
Great Earthquake in Ibaraki prefecture because of the severity of its impact in the Tohoku region.
Nevertheless, the damage in Ibaraki from the tsunami and liquefaction was remarkable from ahistorical perspective. Regarding two issues, this study specifically examines damage impact toresidential areas from the tsunami and liquefaction. Data were collected from all local governments(cities, towns and villages) in Ibaraki by the Department of Emergency and Disaster, Ibaraki
Prefectural Government. Results of investigations were obtained using Geographical Information
System (GIS).
OUTLINE OF DAMAGE TRIGGERED BY THE 2011.3.11 EASTERN JAPAN GREAT EARTHQUAKEAs described above, although it has not strongly attracted public attention, the damage in Ibaraki wascaused not only by strong earthquake motion but also by the subsequent tsunami triggered by the 3.11
earthquake, which was remarkable from a historical perspective in Ibaraki.

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Table 1 Statistical data of damage in major areas in Tohoku and Kanto (at 02 Dec. 2011, after Fire andDisaster Management Agency)
Human damage
Death

MissingSerious
injuryAomoriIwate
Miyagi
Fukushima
SubtotalIbaraki
Kantou Chiba
Tokyo
Subtotal

3
4666
9506
1605
15780
24
20
7
¥51

1
1371
1875
219
3466
1
2

Total

15843

3469

Touhoku

InjuryMinor
injury

3

16

20
36
33
25
14
72

Total
45

161
206
674
226
7
907

¥3,809852
4552
12921161369
195984
22786
9731
11
32528

Building damage
Flood
above
floor
832
7316
1761
2112587900
1414121053
36081810714
162036
1715
42261
153
257
204554
1868

127091230896652951

Complete
dstroy
61
188
4013
181
4443
707
251
90
1048

311
20189
82755
19709
122964
3012
797

5890

Half
destroyPartdestroy

12917

Flood
underfloor

Nonresidence

1420

1194
4148
27786
1108
34236
14411
660
20
15091

13952

50351

323
11299
340
11962
700
720

(Shaded areas show the largest figures in respective columns)
Damage in Tohoku
Table 1 presents data related to human and structural damage in both Tohoku and Kanto, which are themajor areas suffering from the earthquake. At a glance, damage to Tohoku is overwhelmingly greaterthan that in Kanto. Particularly, all figures indicate that damage in Tohoku is concentrated in Miyagi
Prefecture because Sendai, the most populous city in Tohoku, is located there. It holds important
infrastructure and buildings as a virtual capital of Tohoku. Damage to Miyagi is dominated by tsunami
more than by the earthquake although that fact is not clearly apparent in statistical data presented inTable 1.
Damage in Kanto and Ibaraki
In contrast, damage in Kanto differs from that in Tohoku: the fatalities in Kanto were very few, asshown in Table 1. Among the Kanto areas, damage in Ibaraki stands out against that in Tokyo andChiba.
Table 2 Statistical data related to damage in major areas in Ibaraki (at 02 Dec. 2011, after Fire andDisaster Management Agency)
Human damage
InjuryComplete
Death Missing Serious Minor
Total
dstroyinjury injury
Mito
2
974
83
580
Hitachi
6162
168
417
Northern Hitachiohta
122
105
Takahagi
1118
19204
Kitaibaraki
5
1
1187
188
186
9117443460
1492
Subtotal
Kajima
1488
Itako
6688
Inashiki
11130
SouthernKamisu
66139
Ubukata2145103
Hokota11415104
3231331052
Subtotal
12
1
14200
214
468
Others24133674
707
3012
Total

698

Building damage
Halfdestroy
2848
3228
1211
1069
1209
9565
3058
2224
413
1775
453
705
8628
4593
22786

Part
destroy
22554
12505
4204
3891
4680
47834
2897
2620
3281
3310
2877
4674
19659
94543
162036

Flood above Flood under
floor
floor
6
569
0
10
522
1107
155
0
0
25
0
43
223
385
1715

0
162
0
18
117
297
77
0
0
7
0
13
97
306
700

Nonresidence
0
0
107
98
1914
2119
62
541
376
0
51
156
1186
10806
14411

One characteristic feature of damage in Ibaraki appears in relation to damage of buildings andfacilities, as shown in Table 1. Details of structural damage in Ibaraki are presented in Table 2,
showing figures of damage for every representative city, both in northern and southern Ibaraki. It isapparent from Table 2 that damage to buildings in Ibaraki is concentrated in Mito in the north andKajima in the south. However, the main factors caused different damage in both cities. The former in
Mito results from strong seismic motion. The latter in Kashima results from the severe tsunami.
FEATURES OF RESIDENTIAL DAMAGE IN IBARAKI

Distribution of damaged residences

Hotspot

Hot
spot

Fig. 2 Distribution of residences damaged by
the earthquake.

Fig. 1 Distribution of seismic intensity (JMA,2011).

Severely damaged
areas

Fig. 3 Distribution of residences damagedby the tsunami.

Fig. 4 Distribution of residences damaged byliquefaction.

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Data related to the damage to residences in Ibaraki were collected from all local governments(cities, towns and villages) in Ibaraki by the Department of Emergency and Disaster, Ibaraki
Prefectural Government. Using the Geographical Information System (GIS), the following analysis
was mainly conducted based on data collated until 7 July 2011 at the department.
i) How are the damaged residences after earthquake distributed throughout the prefecture?
ii) Which earthquake-related cause mainly triggered the residential damage: tsunami or liquefaction?
Fig. 2 presents the distribution of damaged residences attributable to both tsunami and toliquefaction during the earthquake. Overall agreement is apparent between the severity of seismic
intensity and the distribution of residential damage from the earthquake. Therefore, the larger theseismic intensity was, the severer the residential damage became. At the same time, it seems from Fig.
2 that the damage to residences is concentrated along the coastal region. Nevertheless, it is notdistinguishable from Fig. 2 which of the tsunami or liquefaction was the dominant factor contributing
to increased residential damage. Incidentally, neither the tsunami nor liquefaction affected a nuclear
power station located along the coast in Tokai.
Roughly speaking, it can be inferred from Fig. 1 that two hot spots of strong seismic intensity exist.
These two locations of the hot spot of the seismic magnitude in accordance with Fig. 1 are also
denoted by dotted circles in Fig. 2. Once we indicate hot spots of the seismic intensity in the same
locations in Fig. 2 showing the distribution of damaged residences, it is notable that no agreement canbe found between hot spots of the seismic intensity and the most damaged locations of residences.
Particularly, the number of damaged residences at Tokai village areas is not marked, although theseismic intensity was 6-strong, which is the largest. It is apparent from comparison between Fig. 3 andFig. 4 that, rather in Tokai, the influence of liquefaction is more marked than that of the tsunami.
Conclusively, more than 174,000 residences were damaged in Ibaraki. Among them, completely
damaged residences were 2667 as of 7 July 2011, which corresponds to approximately 14% of alldamaged residences in Ibaraki Prefecture. Tsunami-induced damage is historically great on thenorthern coast in Ibaraki, even in comparison with that which occurred after the Chile earthquake of1960.
Effects of geological characteristics on residential damage
Figure 5 presents the geological situation of Ibaraki. Roughly speaking, northern Ibaraki ismountainous and hilly with a spotted plain along the coast, whereas southern Ibaraki is a plain and in
the lowlands in some areas. Comparison of the residential damage features in Fig. 2 with thegeological situation depicted in Fig. 5 seems not to show that there is not clear agreement between thegeological situation and the distribution of the damaged residences. To clarify this point, bysuperimposing the damage data on Fig. 5, we obtained Fig. 6. The results in Fig. 6 are characterized by
the following.
1) Tsunami-induced damage is concentrated along the coast.
2) In inland areas, damage to residential area is more marked in lowland-like and lowland areas
along the Kokai River and Kinu River, but it is less marked in table lands.
3) In the older geological deposits such as those of the Neocene period, damage was slight.
Those characteristics are, however, quite natural and understandable. This will be mentioned again in
the following chapters.

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Fig. 5 Geological situation of Ibaraki Prefecture (Data Kaizuka et al., 2000).

Fig. 6 Influence of geological conditions on features of residential damage in Ibaraki (After IbarakiPref. 2011 and Kaizuka et al., 2000 ).

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INFLUENCE OF TSUNAMI ON RESIDENTIAL DAMAGE
In comparison with the situation in Tohoku, tsunami-induced damage in Ibaraki is considerably less.
Figure 7 presents a distribution of the tsunami height along the coast in Ibaraki. Those results are
based on an investigation conducted by Dr. Yoshinobu Tsuji, Earthquake Research Institute, The
University of Tokyo, Japan. Fig. 7(a) includes distributions of both Ibaraki and Chiba, and Fig. 7(b)was enlarged from Fig. 7(a) for clarification of the tsunami height distribution in Ibaraki.

Kitaibaraki(a)(b)Takahagi

IBARAKI

Hitachi

Hitachinaka
CHIBA
MitoIBARAKI

Oarai

KashimaFig. 7 Distribution of the tsunami height in inIbaraki in (a) Kanto and (b) Ibaraki(After Dr. Yoshinobu Tsuji, Earthquake ResearchInstitute, The University of Tokyo, Tokyo, Japan).

(a) During the second attack of tsunami.
(b) One month later
Fig. 8 Scenes of a railway embankment and its neighbors near Isohara Town of Kitaibaraki City during
and one month after the second attack of tsunami (taken by Mr. Kazutami Shibata).

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Tsunami-induced damage in Kitaibaraki presents an important example. Figs. 8(a) and 8(b) show
scenes of a railway embankment and its neighboring areas near Isohara Town of Kitaibaraki City
during and one month after the second attack of tsunami. This attacked area is less than 1 km distantfrom the coast. The approximately 4 m high railway embankment served as a barrier against thetsunami: no damage occurred in areas beyond the embankment. Furthermore,, investigation aftertsunami indicated that the railway ballasts were not removed even by the drawing wave of the tsunami.
In other words, it might be said that the wave force of the tsunami was not sufficiently strong to cause
severe damage to the railway embankment and residences when the wave reached these areas.

CONSIDERATION OF INFLUENCES OF LIQUEFACTION ON RESIDENTIAL DAMAGE
Influence of Ibaraki micro-topography on liquefaction

River
CoastRiver

CoastBayBay

Fig. 9 Distribution of liquefied locations on a geological map of Ibaraki (after JGS, 2011and Wakita etal., 2009).
As portrayed in Fig. 4, liquefaction-damaged residences are more numerous in the southern partsof Ibaraki than in the northern parts. To clarify the influence of micro-topography on liquefaction, acomparison was made of Fig. 4 and Fig. 10, revealing that the micro-topographic conditions in Ibaraki
indicating the locations of liquefaction with dotted circles. Information about liquefaction locations in
red circles was investigated by Japan Geotechnical Society (JGS, 2011). The ranges of liquefaction
shown in dotted circles in Fig. 10 show good agreement with tendency areas in Fig. 4 and Fig. 7,
which shows the area and the effects of the geological situation of the liquefaction distribution inIbaraki, respectively. The three circles in dotted red and blue covering Ibaraki, Chiba and Tokyo
indicate that liquefaction mainly took place along the coast, river and bay.

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Typical case history of severe liquefaction in residential areas in Ibaraki

AA’

AA’

Fig. 10 Soil profile of Hinode Town in Itako City.

Fig. 11 Ground profiles at Hinode Town of Itako City (data from DB of Ibaraki Prefecture andKunijiban of MLIT).
As indicated previously in Fig. 4 and Fig. 9, severe liquefaction took place in southern districts,
particularly in the cities of Itako, Kajima, and Kamisu. However, the damage features in three cities
mutually differ, particularly from the perspective of geography, topography, geology, and geotechnicalengineering.
Here we take as an example the case history in Itako City, which suffered the severest damage inIbaraki. Typical damage features in Kamisu and Itako after the Earthquake on 3.11 have frequently704

been introduced by mass media. The liquefaction situation of Hinode Town in Itako City is taken up asan example in the present paper. The land use and the typical subsoil profiles in Hinode Town of
Itako are depicted in Fig. 10. The following tendencies are indicated from Figs. 10 and 11 if
considering the cross section from A to A’ in Fig. 10.
i) The ground consists of transported soils at the surface, sands below the surface, and silt beneathsand.
ii) The groundwater level is high, approximately 1 m from the surface.
iii) Both sandy and silty layers are of the small N-value from zero to several.
These conditions satisfy the high potential of liquefaction occurrence. In other words, the grounds inthis area are well equipped by feasible liquefaction. Only one questionable issue exists of silty layers
to some extent in every profile, although sand layers are expected to have played a role in triggeringliquefaction. The role of silty layers in liquefaction was perhaps a trigger of the amplification ofground motion leading to increased liquefaction.

Sotona -sakaura
reclamation
RiverFig. 12 Ground history of Hinode Town and its vicinity in Itako City
(modified from the map produced by Japan Map Center (JMC), 2011).
Fig. 12 shows the ground history of Hinode Town and its vicinity in Itako City. Figure from 1 to 15
in Fig. 12 correspond to the figures in Fig. 11. By reviewing the ground history of Hinode Town
shown in Fig. 12, roughly speaking, the ground underwent the following before reaching the presentsituation.
i) Reclamation of Uchinami-sakaura for agricultural purposes during 1942–1950.
ii) Reclamation as land readjustment work during 1970–1974. Earthworks were conducted using
dredged sands from Uchinami-sakaura.
The geomorphological configuration based on the situations described above is also responsible for
amplification of seismic ground motion. It can be seen from Fig. 12 that the residences in HinodeTown are built upon the basined deposition by reclamation. This situation resembles that in Mexico
City when the Michiokan Earthquake struck in 1985 (Mendoza and Auvinet, 1986), although sub-soils
in Mexico City consist of highly plastic clay with high water contents, which differ from silty soils in705

Hinode Town in Itako City. Presumably, the similarity of geometrical configuration of soil deposits
with a bowl type of geomorphologic situation between Mexico City and Itako City is also related tothe amplification of seismic motion.

CONCLUSIONS
Little attention has been given by the mass media to damage triggered by the 3.11 Eastern Japan Great
Earthquake in Ibaraki prefecture because of the relative severity of effects in the Tohoku region.
Nevertheless, the damage in Ibaraki from the tsunami and liquefaction was remarkable from ahistorical perspective in Ibaraki. Regarding two issues, this study specifically examines damage
impacts to residential areas from the tsunami and liquefaction. Data were collected from all local
governments (cities, towns and villages) in Ibaraki by the Department of Emergency and Disaster,Ibaraki Prefectural Government. Results from investigations were demonstrated using Geographical
Information Systems. The following findings were obtained from the present investigation.
i) The tsunami damage was concentrated along the entire coastal area from north to south. Particularly
those areas damaged by tsunami are concentrated on the northern coasts.
ii) Liquefaction damage occurred in more than 84% of all Ibaraki, not only in coastal areas but also ininland areas. However, the areas impacted by liquefaction were more severely affected in the southernparts of Ibaraki.
iii) Therefore, these characteristics of earthquake-induced damage in residences should be examinedwhen planning cities that are robust and resilient against the coming great earthquakes in the future.
A review of the damage in residential areas in views of geotechnical engineering indicatespossible cases in which liquefaction triggered an increase of the tsunami damage as a compoundgeo-disaster. This is an important issue to be pursued in further investigations in the future.
ACKNOWLEDGMENTS
This research was partly supported by the Environment Research and Technology Development Fund(S-8) of the Ministry of the Environment, Japan (FY2010-FY2014) and Grant-in-Aid for Scientific
Research from the Ministry of Education, Science, Sport and Tourism (FY2011-FY2013). Thesesupports shall be highly appreciated. Basic data related to the damage of residences was provided by
the Department of Fire and Disaster Management, Ibaraki Prefectural Government. We would like toexpress sincere thanks for their kind support.

REFERENCES
Fire and Disaster Management Agency (2011).”Report No. 142 of East Japan Great Earthquake”.
Kaizuka, K., Koike, K., Endo, K., Yamazaki, H. and Suzuki, T(ads.)(2000), “Regional geomorphologyof the Japanese islands vol. 4, Geomorphology of Kanto and Izu-Ogazawara”, Univerisity of Tokyo
Press,Tokyo, 349p.
Kanto Branch of MLIT and JGS (2011).”Report on liquefaction in Kanto District during East Japan
Off-Pacific Earthquake (in Japanese)”, p. 58.
Mendoza, M. J. and Auvinet, G. (1988). “The Mexico earthquake of September 19, 1985: Behavior ofbuilding foundations in Mexico City”, Earthquake Spectra, EERI, Vol. 4(4), 835-853.
Tsuji, Y. (2011). “Tsunami height in Ibaraki and Chiba coasts”, Earthquake Research Institute, The
University of Tokyo.
http://outreach.eri.u-tokyo.ac.jp/eqvolc/201103_tohoku/eng/#tsunami%20height.
Wakita, K., Igawa, T. and Takarada, S. (ads)(2009). “Seamless geological map of Japan at a scale of1:200,000 DVD edition”, Digital Geoscience Map G-16, Geological Survey of Japan, AIST.

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