BOOK OF ABSTRACTS
THE THIRD INTERNATIONAL WORKSHOPON COASTAL DISASTER PREVENTIONANDTSUNAMI HAZARD MAP SEMINAR
February 12 - 13, 2007
Regency Room, Mount Lavinia Hotel, Colombo, Sri Lanka

Organizers（Japan）
Port and Airport Research Institute
Coastal Development Institute of Technology
Ministry of Land Infrastructure and Transport
Organizers（Sri Lanka）
University of Moratuwa
National Science Foundation
Disaster Management Centre
Supporting Organizations
Japanese Section of International Navigation Association
UJNR Panel on Wind and Seismic Effects

The 3rd International Workshop on Coastal Disaster Prevention
Date
February 12 - 13, 2007
Venue
Regency Room, Mount Lavinia Hotel, Colombo, Sri Lanka
Organizers（Japan）
Port and Airport Research Institute
Coastal Development Institute of Technology
Ministry of Land Infrastructure and Transport
Organizers（Sri Lanka）
University of Moratuwa
National Science Foundation
Disaster Management Centre
Supporting Organizations
Japanese Section of International Navigation Association
UJNR Panel on Wind and Seismic Effects
Objectives
Tsunami disasters are summarized through overviews of damage by previous
tsunamis around the world and advanced measures to prevent and mitigate
tsunami disasters are presented and discussed in the workshop.
AgendaFebruary 12 (Monday)
9.30 – 10:30 - Opening Ceremony- Mr. Makoto Owada (PARI, Japan)- Prof. S.S.L. Hettiarachchi (Moratuwa University,
SR)- Mr. Masahiko Furuichi (MLIT, Japan)- Speech by Chief Guest/Guest of Honour
10:30 – 11:00 - Tea
11:00 – 12:30 - Session (1) Tsunami Disasters and Initiatives forPrevention/Mitigation Activities around the world- Prof. S.S.L. Hettiarachchi (Moratuwa University,
SR)“Development of the Indian Ocean TsunamiiWarning System”- Dr. Shigeo Takahashi (PARI, Japan)“Tsunami Disasters and Their Mitigation in
Japan”- Prof. W.P.S. Dias (Moratuwa University, SR)“Development of Design Guidelines for Buildings
against Tsunamis”
12:30 – 13:30 - Lunch
13:30 – 15:00 - Session (2 a) Tsunami Disasters and Initiatives forPrevention/Mitigation around the world- Dr. S.P. Samarawickrama (Moratuwa University,
SR)“Strategic Approach and Investigations on
Mitigatory Measures”- Dr. Subandono Diposaptono (MMAF, Indonesia)“Mitigating Tsunami Hazards: An Indonesian
Challenge”- Dr. Anat Ruangrassamee (Chulalongkorn University,
Thailand)“Effect of Tsunamis on the Eastern Coast of
Thailand”
15:00 – 15:30 - Tea
15:30 – 17:30 - Session (2 b) Tsunami Disasters and Initiatives forPrevention/Mitigation around the world- Dr. Jose Miguel Montoya Rodriguez (IMT, Mexico)“Tsunami Disasters and Prevention/Mitigation
Activities in Mexico (tentative)”- Dr. John R. Headland (Moffatt & Nichol Engineers,
USA)“Tsunami Impacts on Moored and Maneuvering
Ships”- Dr. Yoshiyuki Kaneda (JAMSTEC, Japan)“Advanced
Ocean
Floor
Networkfor
Earthquakes and Tsunamis around the Nankai
Trough in Southwestern Japan - Towards theUnderstanding of Mega-Thrust Earthquakes -“- Dr. Yuji Nishimae (JMA, Japan)“Tsunami Warning Service in Japan”
18:00 – 20:00 - Reception- Mr. Susumu Murata (CDIT, Japan)- Remarks from Sri LankaiiFebruary 13 (Tuesday)
09:00 – 10:30 - Session (3 a) Advanced Technologies of Tsunami
Disaster Prevention/ Reduction- Dr. Taro Arikawa (PARI, Japan)“Hydraulic Characteristics of Buoyancy-Driven
Vertical Piling Breakwater”- Prof. Koji Fujima (NDA, Japan)“Numerical Simulation of Indian Ocean Tsunami
Using Linear and Nonlinear Dispersive Wave
Theory”- Prof. Solomon Yim (Oregon State U., USA)
“Structure-Structure
ImpactModeling
for
Tsunami Debris Flow”
10:30 – 11:00 - Tea
11:00 – 12:30 - Session (3 b) Advanced Technologies of Tsunami
Disaster Prevention/ Reduction- Mr. Susumu Murata (CDIT, Japan)“Numerical Model for Estimation of Damages
due to Tsunami”- Prof. Ahmet C. Yalciner (METU, Turkey)“Determination of Periods of Free oscillations for
the Irregular Shaped Basins by NumericalTechnique”- Dr. Takashi Tomita (PARI, Japan)“Development of Tsunami Damage Estimation
Tool”
12:30 – 12:40 - Closing Ceremony- Mr. Susumu Murata (CDIT, Japan)
12:40 – 13:40 - Lunch

iii

iv

Tsunami Hazard Map Seminar
Date
February 13, 2007
Venue
Regency Room, Mount Lavinia Hotel, Colombo, Sri Lanka
Organizers (Japan)
Ministry of Land Infrastructure and Transport
Port and Airport Research Institute
Organizers (Sri Lanka)
University of Moratuwa
National Science Foundation
Disaster Management Centre
Objectives
A tsunami hazard map provides a visual reference identifying historical andexpected tsunami risks, and is a useful tool to prevent and mitigate future
tsunami disasters. The seminar will focus attention on the outline of tsunami
hazard maps and issues for its usage and promotion. Future direction ofdevelopment of tsunami hazard maps and their relevance in developing
countries will also be discussed.
AgendaFebruary 13, 2007
14:00 – 14:15 - Opening Ceremony- Mr. Masahiko Furuichi (MLIT, Japan)
14:15 – 16.00 - Presentations- Dr. Takashi Tomita (PARI, Japan)“Hazard Map to Build the Understandings andAwareness of Tsunami Disasters”- Mr. Kentaro Kumagai (NILIM, Japan)“Utilization and Promotion of Tsunami Hazard
Map“- Dr. Nimal Wijayaratna (University of Ruhuna, SR)“Hazard Mapping - A Sri Lankan Experience”- Dr. Subandono Diposaptono (MMAF, Indonesia)“Tsunami Risk Map in West Sumatera
Indonesia”
v

16:00 – 16:30 - Discussion
16:30 – 16:40 - Closing Ceremony- Dr. Shigeo Takahashi (PARI, Japan)viContents
The 3rd International Workshop on Coastal Disaster Prevention
DE VEL O PME NT O F T HE I NDI AN O CE AN TSUNAMIW ARNI NG SYST E M -----------------------------------------------------------------S.S.L. Hettiarachchi and S.P. Samarawickrama
T SUNAMI DISASTE RS AND T HE I R MI TI G AT I O N I N J APAN-------------Shigeo Takahashi

1
3

DE VEL O PME NT O F DE SI G N G UI DEL I NE S FO R BUIL DI NG S
AG AI NST TSUNAMIS ---------------------------------------------------------------W.P.S. Dias

15

ST RAT EG I C APPRO ACH AND I NVEST I G ATI O NSO N MIT IG ATO RY ME ASURES ---------------------------------------------------S.P. Samarawickrama, S.S.S. Hettiarachchi, A.H.R. Ratnasooriya, T. Welhena and H.J.S. Fernando

16

MI T I G AT I NG TSUNAMI H AZARDS: AN I NDO NESI AN CH AL LE NGE --Subandono Diposaptono

18

E FFE CT O F T SUNAMIS O N T HE E ASTE RN CO AST O F TH AIL AND----Anat Ruangrassamee and Nopporn Saelem

31

T SUNAMI I MPACTS O N MO O RE D AND MANE UVE RI NG SH I PS ---------John R. Headland

33

ADVANCE D O CE AN FL OO R NET W O RK FO R E ART HQ UAKESAND TSUNAMIS ARO UND TH E NANK AI T RO UG H
I N SO UT H WESTE RN J APAN
- TO W ARDS T HE UNDE RST ANDI NG O F MEG A-T H RUSTE ARTH Q UAK ES - --------------------------------------------------------------------Yoshiyuki Kaneda, Katsuyoshi Kawaguchi, Eiichiro Araki, Hiroyuki Matsumoto,Takeshi Nakamura, Shinichiro Kamiya, Takane Hori and Toshitaka Baba.
T SUNAMI W ARNI NG SE RVI CE I N J APAN ------------------------------------Yuji Nishimae

35

37

H YDRAUL I C CH ARACTE RISTI CS O F BUO YANCY-DRI VE N
VE RT I CAL PI L I NG BRE AK W AT E R --------------------------------------------Taro Arikawa and Fumitake Nakano

39

NUME RI CAL SI MUL AT IO N O F I NDI AN O CE AN T SUNAMIUSI NG L I NE AR AND NONL I NE AR DISPE RSI VE W AVE T HE O RY--------Koji Fujima, Yoshinori Shigihara, Takashi Tomita and Kazuhiko Honda

41

vii

ST RUCT URE -STRUCT URE I MPACT MO DELI NG FO R TSUNAMI
DE BRIS FL O W ------------------------------------------------------------------------Solomon C. Yim and Gang Cao

43

NUME RI CAL MO DEL FO R ESTI MAT IO N OF DAMAG E S
DUE T O T SUNAMI -------------------------------------------------------------------Susumu Murata, Yoshiji Koyano and Tetsuya Tamehiro

45

DE TE RMI NATI O N O F PE RIO DS O F FREE OSCIL L AT I O N
FO R T HE I RREG ULAR SH APE D BASI NS BY
NUME RI CAL T E CH NI Q UE ---------------------------------------------------------J Ahmet C Yalciner and Efim N Pelinovsky

47

DE VEL O PME NT O F T SUNAMI DAMAG E E ST I MATI O N TO OL ---------Takashi Tomita, Kazuhiko Honda and Taro Arikawa.

viii

50

Tsunami Hazard Map Seminar
H AZARD MAP TO BUIL D T HE UNDE RST ANDI NG S
AND AW ARE NESS O F TSUNAMI DI SAST E RS --------------------------------Takashi Tomita

53

UT I LI ZAT IO N AND PRO MOT IO N O F TSUNAMI H AZARD MAP --------Kentaro Kumagai55

H AZARD MAPPI NG - A SRI L ANK AN EXPERI E NCE -----------------------Nimal Wijayaratna

58

ix

THE THIRD INTERNATIONAL WORKSHOPON COASTAL DISASTER PREVENTION

DEVELOPMENT OF THE INDIAN OCEANTSUNAMI WARNING SYSTEM

Hettiarachchi SSL
Department of Civil Engineering, University of Moratuwa, Sri Lanka, sslh@civil.mrt.ac.lk

Samarawickrama SP
Department of Civil Engineering, University of Moratuwa, Sri Lanka, samans@civil.mrt.ac.lk

Aftermath of the Indian Ocean Tsunami the need for a reliable tsunami warning system similar to that
operating in the Pacific Ocean was identified. The UNESCO/ International Oceanographic Congress(IOC) in collaboration with the Indian Ocean states and other stakeholders initiated the establishment of atsunami early warning system in March 2005. The initial task was to reach agreement on the structure andoperation of such a warning system.
An effective tsunami warning system must include four key components, namely,
1) detection of hazard2) assessment of risk
3) issuing the warning4) dissemination of the warning5) community preparedness to respond as advised in advance
It was agreed that the Indian Ocean Tsunami Warning System (IOTWS) will comprise a coordinatednetwork of national systems and capacities, and will be part of a global network of early warning systems
for all ocean related hazards. Therefore within the IOTWS, each Member State will have theresponsibility to issue warning within their respective territories. For this purpose the respective warning
centres of individual nations must be well equipped to receive and analyse information, detect the hazard,
assess the risk and issue the warning to the community who have been adequately trained and coached on
how best to respond to the specific type of warning issued. The UNESCO/IOC initiatives led to theestablishment of the Intergovernmental Coordination Group (ICG) which meet regularly to report, discussand monitor the initiatives and actions taken by the nations individually and jointly to contribute to theestablishment of the IOTWS. A reliable tsunami warning system requires information arising from three
instrumentation networks, namely, an improved seismographic network, a real time sea level observation
network covering the Indian Ocean basin and the deployment of advanced deep-sea pressure sensors
capable of detecting the tsunami as it travels over the deep ocean. It also requires the availability of wellequipped national warning centres which are able to detect the hazard, analyse, assess the risk and issue
an appropriate warning. The nations must educate its people on disaster preparedness and how to respondto a specific type of warning.

1In order to achieve the specified objectives related to the establishment of the IOTWS based on national
and international contributions, the ICG agreed on the establishment of Working Groups covering criticalareas of the IOTWS. The said working groups comprising representatives of the nations and international
experts are jointly contributing to the establishment of the IOTWS.
At present there are six working groups namely,
1) Seismic Measurements, Data Collection and Exchange
2) Sea level data collection and exchange, including deep ocean tsunami detection instruments
3) Risk Assessment
4) Tsunami hazard identification and characterization, including modeling and prediction5) Establishment of a System of Interoperable Centres
6) Mitigation, Preparedness and Response
During the course of 2005/6 progress has been made in improving seismographic networks, sea level
observation networks and the capabilities of national warning centres. There have been considerable
efforts in identifying and providing access to wide range of relevant data bases and networking. Of
significant interest is the fact that India, Indonesia, Malaysia, Thailand and Australia are planning the
deployment of deep sea buoys which are currently being developed. The deep sea buoys which form a
key element of the IOTWS will enable the detection of tsunamis arising in Sunda arc and provide early
warning to the Indian Ocean states. It is expected that around 10 buoys will be in place by the end of 2006.
The presence of these buoys will be of great advantage to countries like Sri Lanka which are located at aconsiderable distance from the potential fault line providing them a warning of the order of 1.0-1.5 hours.
Through the respective working groups the nations maintain a working relationship on all issues related toeach group.
One of the key areas of research and development refers to scenario modelling of tsunamis which haveoccurred previously and potential tsunamis which are most likely to occur in the future. Previous
tsunamis have been modeled successfully providing a broader understanding of exposure of Sri Lanka to
the hazard. In the absence of near-shore bathymetric data, the models have not covered areas closer to theshoreline. In effect the near-shore transformation processes and interactions that amplified the wave havenot been incorporated. It is evident that simulations for a range of possible scenarios, incorporating the
combined influence near-shore transformation and inland dissipation processes should be implemented inorder to understand the exposure and impact on the coastal zone. For this activity to be implemented it isnecessary to have quality data of the near-shore bathymetry and land topography. The results from thisexercise should be stored in a relational database. In the event of a tsunami this database will provide
initial information on the potential exposure to the hazard and impacts. Modelling should then be carriedout as soon as information is available on the earthquake and should be further refined by remodelingwith data available from the deep sea buoys when they are in place. By doing so it would be possible toassess the potential exposure and impacts of the tsunami if it was to occur and will greatly enhance theearly warning process and its dissemination to the people to be affected.

2

TSUNAMI DISASTERS AND THEIR MITIGATION IN J APAN

Shigeo TAKAHASHIPort and Airport Research Institute, Nagase, Yokosuka, Japan 239-0826, takahashi_s@pari.go.jp
1. Introduction
Disaster prevention technologies developed from experience with many tsunamis in Japan are reviewed inthis paper. Also introduced is recent research on the prediction of disasters, real-time tsunami prediction
and new countermeasures following the devastating Indian Ocean Tsunami.
2. Recent Tsunami Disaster s in
J apananddevelopment⑩Hkkaido Nanseioki（ M７．８）

of①Meiji-Sanriku（ M８．５）

July 12, １９９３

○２３０

June 15, 1896
○２２，０００ ３８．２ｍ○３０ｍ

counter measures⑩④Showa-Sanriku（ M８．１）⑨Nihonkai-chubu（ M７．７）(1) Tsunamis and their disaster s

May 26, １９８３⑨

○１０４ １４ｍ

In Japan, tsunami disasters occur

September 1, 1923

○１４２，８０７

disasters can be found in many old
including

the

first

documented

tsunamiin

684.

Tsunamidisasters○３，０６４ ２９ｍ②Kanto（ M７．９）

very frequently. Historical tsunami
documents

March 3, 1933

①④

②
⑤
⑦

⑦Showa-Nankai（ M８．０）

occur

December 21, １９４６

○ １，４４３⑤Tou-Nankai（ M７．９）
December 7, 1944

⑧Chilie（ M９．５）

○９９８

○ １４２

May 23, 1960

６ｍ

６m

approximately once every 10 years,【Copy right】JMA

and huge disasters once in a 100

Fig. 1 Recent major earthquakes in Japan (The figure is fromyears due to the active movement

reference paper of Ports and Harbor Bureau of MLIT modified

of tectonic plates around thefrom the original figure of Japan Meteorological Agency.)

Japanese Islands.
Figure 1 shows the recent major tsunamis in Japan. Tsunamis attack not only the Pacific Ocean
coastline but also the Japan Sea coastline. The Meiji-Sanriku Tsunami in 1896 killed 22,000 people,
which is the largest casualty in modern-age Japan. A tsunami arising from an earthquake off the Chilean
coast attacked various locations in Japan and killed more than 100 people in 1960. The tsunami reachedJapan after about 22.5 hours, traveling approximately 18,000 km with a speed of about 800 km/h.
The Nihonkai-Chubu Tsunami disaster, which occurred 20 years ago which killed about 100 in 1983,
and the Hokkaido Nanseioki Earthquake Tsunami killed more than 200 people in 1993.
(2) Development of Counter measures
From the 1950’s, many administrative measures for disaster prevention have been taken, including thoseagainst tsunami disasters. In 1952, a tsunami warning system was established in Japan and after the
Chilean Tsunami disaster, international cooperation for a distant tsunami warning system was established.
In 1956, the Seacoast Law was implemented from the viewpoint of management of seacoasts including
countermeasures against tsunamis and storm surges. In 1961, the Disaster Countermeasures Basic Act
was established and a Central Disaster Management Council has been established in 1962, and in 1963, a3

Basic Disaster Management Plan was prepared.
After the coastal disasters, the research on coastal disasters was promoted and the construction ofcoastal defenses was accelerated throughout Japan.
3. Cur rent Counter measures
In the very near future, earthquakes have been predicted for the Tokai, Tonankai and Nankai regions inaddition to the area off the Miyagi coast. The central and local governments in these regions are preparing
for expected tsunamis in various ways.
Non-structural measures are being prepared to mitigate expected tsunami disasters including 1.
Tsunami warning system, 2. Dissemination of tsunami knowledge, 3. Land usage planning, and 4.
Effective evacuation measures for low-lying areas(hazard maps, evacuation towers etc.) In addition, many
structural countermeasures are being prepared against calculated tsunami heights, including tsunami
seawalls, river water-gates, and on-land water gates.
The Central Disaster Management Council of the Cabinet Office is responsible for disaster mitigation.
The Ministry of Land Infrastructure and Transport is implementing countermeasures against natural
disasters including tsunamis.
4. Research on New Integr ated Tsunami Counter measures at PARI
Intensive studies have begun to establish integrated disaster mitigation measures in various research
institutions around the world after the Indian Ocean Earthquake Tsunami. The Port and Airport ResearchInstitute (PARI) which had made studies on tsunami since the Chilean Tsunami, established a tsunami
research center to develop new integrated countermeasures for expected huge tsunamis in Japan, which
includes:1.

Disaster prediction with ‘dynamic hazard maps’

2.

Vertical evacuation in tsunami-resistant buildings

3.

Real-time tsunami prediction with monitoring4.

New structural countermeasures (Tsunami gates)

5.

Greenbelt

5.

Concluding Remarks

The Indian Ocean Tsunami caused devastating disasters. People in the world experienced the disasters
directly and indirectly, i.e. visually through TVs, which will contribute greatly to reduce tsunami disasters
in the future. But they will disappear gradually from the memories of people. Not just the experiences ofthe disasters but the analyses of the disasters are important, and we should learn from the experiences.
They should be integrated into advanced disaster mitigation technologies.
For example, to enable safe evacuation, people should be given adequate information on actual
tsunami inundation disasters, which includes the actual risk of human casualties and potential of damage
to houses and facilities in the coasts, in addition to information on tsunami height. The technology toprovide more specific and concrete information (scenarios) on tsunami disaster is needed. The advancetechnologies should be developed with an international cooperation including researchers from Sri Lanka.

4The 3rd Inter national Wor kshop on Coastal Disaster Pr evention

TSUNAMI DISASTERS AND THEIR MITIGATION IN JAPANS. Takahashi
Director, Tsunami Research Center, Port and Airport Research Institute3-1-1, Nagase, Yokosuka, Japan, 239-0826
takahashi_s@pari.go.jp

ABSTRACT: Disaster prevention technologies developed from experience with many tsunamis in Japan are
reviewed in this paper. Also introduced is recent research on real-time tsunami prediction and the prediction ofdisasters following the devastating Sumatra Earthquake Tsunami.

1.

INTRODUCTION

Civil engineering research on the coastal zone is very active in Japan as this zone is very heavily populated andeconomically very important. Recent research has been directed toward disaster prevention and environmental
preservation.
Intensive research is being done on disaster prevention in the coastal zones of Japan. Research on typhoon
disasters started after the Isewan Typhoon in 1959, which killed about 5,000 people. After the Chilean Tsunami
disaster in 1960, research began on tsunami disasters, with significant progress after the Nihonkai-chubu
Tsunami in 1983 and the Hokkaido-Nanseioki Tsunami in 1993.
On December 26, 2004, the devastating Indian Ocean Tsunami disaster occurred, killing about 300 thousandpeople [1-5]. Studies have been focused on clarifying the factors of the tsunami disaster and also to establish
integrated disaster mitigation measures around the world.
The contents of this paper are as follows:
1. Introduction
2. Recent Tsunami Disasters in Japan and development of countermeasures
3. Current Countermeasures
4. Research on New Integrated Tsunami Countermeasures
5. Concluding Remarks
Sections 2 briefly reviews recent tsunami disasters and development of countermeasures against expectedtsunamis in Japan using reference documents reported by the Ports and Harbor Bureau of the Ministry of Land,
Infrastructure and Transport, Japan. Section 3 introduces the current countermeasures in Japan Section 4
introduces integrated research being conducted at the Port and Airport Research Institute. New disastermitigation measures are needed to reduce the casualties due to huge tsunamis.

2.

RECENTTSUNAMICOUNTERMEASURESDISASTERS

IN

5

JAPAN

AND

DEVELOPMENTOF“Tsunami” is a Japanese word written
using two Chinese characters. ‘Tsu”
means harbor and ”nami“ means wave,
and therefore “tsunami” means “harborwave” in Japanese. Although tsunami is
not apparent in deep seas but it become
violent in coasts. Especially people canfind tsunami in harbors. This is thereason of the name.

North American Plate
Pacific Plate
Crust

Eurasia Plate

MantleIt became internationally popular after
the Meiji-Sanriku Tsunami in 1896 andthe Showa-Sanriku Tsunami in 1933.
News reports of devastating damages
appeared around the world.

Philippine Plate

Fig. 1 Subduction zones and plates around Japan
In Japan, tsunami disasters occur veryfrequently. Historical tsunami disasters can be found in many old documents including the first documented
tsunami in 684. Tsunami disasters occur approximately once every 10 years, and huge disasters once in a 100
years. This is due to the active movement of tectonic plates around the Japanese Islands. The verticaldisplacement of plates due to subduction zone earthquakes results in tsunami generation[6,7].
Figure 2 shows the recent major
tsunamis in Japan. Tsunamis attack notonly the Pacific Ocean coastline but
also the Japan Sea coastline. All ofthese tsunamis were generated fromseas near the Japanese Islands, exceptthat from the Chilean Tsunami in 1960.

⑩Hkkaido Nanseioki（ M７．８）①Meiji-Sanriku（ M８．５）

July 12, １９９３

○２３０

June 15, 1896
○２２，０００ ３８．２ｍ○３０ｍ⑩④Showa-Sanriku（ M８．１）⑨Nihonkai-chubu（ M７．７）
May 26, １９８３⑨

○１０４ １４ｍ

March 3, 1933①④

○３，０６４ ２９ｍ②Kanto（ M７．９）
September 1, 1923

○１４２，８０７

Figure 3 shows a picture about the②
Meiji-Sanriku Tsunami in 1896 which⑤⑦
killed 22,000 people, the largest⑤Tou-Nankai（ M７．９）⑧Chilie（ M９．５）
casualty in modern-age Japan. The
May 23, 1960
December 7, 1944
⑦Showa-Nankai（ M８．０）
shaking due to the earthquake was not
○９９８
○ １４２
６ｍ
December 21, １９４６
○ １，４４３
６m
significant along the coast, and【Copy right】JMA
therefore the people did not realize that Fig. 2 Recent major earthquakes in Japan (The figure is fromthere was a risk of a tsunami attack and reference paper of Ports and Harbor Bureau of MLIT modified
did not evacuate. The tsunami hit at from the original figure of Japan Meteorological Agency.)
night (8 o’clock at night, 35 minutes
after the quake) at heights exceeding 10
m (maximum recorded runup height 38.2 m).
This disaster can be considered to be similar tothat of the Indian Ocean Tsunami since no warning(no evacuation) and almost no coastal defenses
existed against such a large tsunami. In 1933, theShowa-Sanriku Tsunami attacked the same region
again but the number of casualties was greatly
reduced to 100 due to evacuation before thetsunami attack.
From the 1950’s, many administrative measures fordisaster prevention have been taken, including
those against tsunami disasters. In 1952, a tsunami
warning system was established in Japan. In 1956, Figure 3 A picture of the Sanriku Tsunami Disasterthe Seacoast Law was implemented from theviewpoint of management of seacoasts including
countermeasures against tsunamis and storm surges. In 1961, the Disaster Countermeasures Basic Act wasestablished and in 1962, an act went into effect concerning special financial support to deal with designated6disasters of extreme severity. A Central Disaster Management Council has been established and in 1963, a Basic
Disaster Management Plan was prepared.
Figure 4 shows an inundation disaster caused by the Chilean Earthquake Tsunami arising from an earthquake off
the Chilean coast. The tsunami reached Japan after about 22.5 hours, travelling approximately 18,000 km with aspeed of about 800 km/h. The tsunami attacked various locations in Japan from Hokkaido in the north to
Okinawa in the south. People could not comprehend the tsunami danger from such a distance and the tsunami
warning system did not work. After this disaster, international cooperation for a distant tsunami warning system
was established.
Just before the Chilean Earthquake Tsunami disaster, a devastating storm surge attacked the Isewan Bay in 1959
killing about 5,000 people. After these two coastal disasters, the research on coastal disasters was promoted andthe construction of coastal defenses was accelerated throughout Japan.

Fig. 5 Inundation due to Nihonkai-chubu
Tsunami in Iwasaki Village

Fig.4 Inundation in Suzaki due to Chilean Tsunami

Fig. 6 Wave runup at Matsuzaki Port
Fig. 7 Tsunami height along Japan Sea coasts

Fig. 8 Aonae in Okushiri Island just after
Tsunami attack

Figure 9 Damaged houses and ships

7

Figure 5 shows a photo of the Nihonkai-Chubu Tsunami disaster, which occurred 20 years ago. Figure 6 shows aphoto of the tsunami running up to 5 m near Matsuzaki Port; it was taken by a construction worker. Due to thewarning system, the number of casualties was reduced to about 100. Also, coastal defenses against the storm
waves were effective. The casualties included children who were on a picnic on the coast and people working inthe sea, such as fishermen and marine construction workers. The transmission of the warning to these people wasdifficult. Figure 7 shows the distribution of tsunami heights along the Japan Sea coast. It should be noted thatsignificant damage appeared where the tsunami height exceeded 4 m and devastating damages occurred where
the tsunami height was near 10 m[8].
Figure 8 is a photo of the Aonae district of Okushiri Island just after the Hokkaido Nanseioki
Earthquake Tsunami[9], which is known as the Okushiri Tsunami, because the most serious damage
was to Okushiri Island. The maximum tsunami run-up height was more than 30 m and more than 200
people were killed.

3.

CURRENT MEASURES FOR TSUNAMI DISASTER PREVENTION(1)Okushiri Island
New Town

Artificial High Ground11m seawall
6m Seawall

Fishery PortPark
Seawall

Reclamation

Fig. 11 Completed tsunami mitigation works

Figure 10 Land use planning in Aonea district
After the disaster, construction work was implemented
to establish a total disaster prevention system for
Okushiri Island. Figure 10 shows a map of land use
planning, where houses in the most severely damaged
areas were to be moved to high land areas and someland reclamation would be done to create higher land
areas. Figure 11 shows the seawalls in front of thereclaimed lands and an artificial high ground in thefishery port where fishermen can work daily on the firstfloor and use the second floor for evacuation.

[Probability of occurrence of subduction zone
earthquake within 30 years]
Nemuro offshore(Approx. M 7.9)

Hokkaido
northwestern offshore(Approx. M 7.8)

40%
Tokachi offshore(Around M 8.1) 0.5%

0.1%
Akita Prefecture
offshore(Approx. M 7.5)

Sanriku northern offshore(Around M 8.0) 7%

3%

Miyagi Prefecture offshore(Around M 7.5)

Sado Island northern offshore(Approx. M 7.8) 6%

99%

Sanriku offshore to Boso offshore
Sea of Aki to Bungo Channel(M6.7 to 7.4)

Tsunami-type (Around M 8.2)

Genroku-type Kanto Earthquake(Approx. M 8.1) 0%

Sea of Hyuga(Around M 7.6)

Minami-kanto(Approx. M 6.7 to 7.2)

10%
[Source]
Prepared by processing
reference material from the
Headquarters for Earthquake
Research Promotion

20%
7%

Normal fault-type (Around M 8.2)

40%

Nankai (Around M 8.4)

50%
-7-

Tonankai(Around M 8.1)

Tokai
(Approx. M 8.0)

60%

84%

70%
Taisho-type Kanto Earthquake(Approx. M 7.9) 0.9%(2) Expected Tsunamis
Fig.12 Expected earthquakes(from reference
Figure 12 shows the occurrence probabilities within 30
material of the execution office of the Earthquake
years of subduction zone earthquakes around the Research Committee)
Japanese Islands. In the very near future, earthquakes
have been predicted for the Tokai, Tonankai and Nankai regions in addition to the area off the Miyagi coast. The
central and local governments in these regions are preparing for expected tsunamis in various ways.
The Central Disaster Management Council of the Cabinet Office is responsible for disaster mitigation. The
Ministry of Land Infrastructure and Transport is implementing countermeasures against natural disasters
including tsunamis. To prepare for the expected earthquakes and tsunamis, the Large-Scale Earthquake
Countermeasures Special Act was passed in 1978, which encourages having basic plans for earthquake disasterprevention including the definition of jurisdictions and responsibilities for disaster management, a disastermanagement system and plan, disaster preparedness, emergency actions and recovery, financial measures, stateof emergency plans, etc. A new law, the Tonankai and Nankai Earthquake Countermeasure Special Act, waspassed in 2002.

8

(3) Non-structural Countermeasures
The disaster caused by the Nihonkai-chubu Earthquake
Tsunami showed that not only hardware measures but
also software measures are needed to mitigate expectedtsunami disasters. Software measures include:
a. Tsunami warning system
b. Dissemination of tsunami knowledgec. Land usage planningd. Effective evacuation measures for low-lying areas.
(hazard maps, evacuation towers etc.)
The Japan Meteorological Agency developed a new
warning system for local earthquake tsunamis from1999 to issue a warning within 3 minutes using atsunami database of 100,000 calculated tsunamis. The
Fig. 13 Hazard map for Suzaki City
agency also has a warning system for distant earthquake
tsunamis that was established with international cooperation.
Figure 13 shows a hazard map prepared for Suzaki City. The ‘Manual for Tsunami and Strom Surge Hazard
Maps[11]’ has been used by some local governments to prepare hazard maps in collaboration with engineers andlocal citizens. Such a map can be useful for effective evacuation of the residents and also aid in the planning ofdisaster mitigation.
(4)Structural Countermeasures
Many structral countermeasures are being prepared against
calculated tsunami heights, including tsunami seawalls,
river water-gates, and on-land water gates.
Figure 14 shows a tsunami breakwater which is underconstruction at a baymouth in Suzaki Port, Japan. Tsunami
breakwaters were and are being constructed in expectedtsunami areas (especially areas affected by major tsunamis
in the past) to reduce the intrusion of a tsunami into theharbor. Ordinary breakwaters can also prevent a tsunami tosome extent, especially reducing a direct attack of thetsunami wave front, as has been observed in recent tsunamis
in Japan[10].

4.

Fig.14 Tsunami breakwater in Suzaki

RESEARCH ON NEW INTEGRATED TSUNAMI COUNTERMEASURES

Intensive studies have begun to establish integrated disaster mitigation measures in various research institutions
around the world after the Indian Ocean Earthquake Tsunami. The studies include
1. Generation of Earthquake
Generation mechanism of earthquake, Prediction and Early warning method of earthquake
2. Generation and Propagation of Tsunami
Numerical simulation of generation and propagation of tsunami, Early warning method of tsunami,
3. Run-up of Tsunami
Numerical simulation (prediction of water current and height)
4. Tsunami Disaster
Prediction(Numerical simulation) of Tsunami forces
Prediction(Numerical simulation) of Failures of buildings and facilities
Prediction of behavior of floating objects
Prediction of human safety
5. Non-structural Countermeasures
Hazard map making, Evacuation simulation, Dissemination of tsunami knowledge
Real time prediction of incident tsunami
6. Structural Countermeasure
Tsunami breakwaters and seawalls, Tsunami gates, Green-belt, Evacuation tower
7. Disaster Prevention Policy and Administration
Risk management ( Planning of evacuation, recovery and reconstruction, Evacuation drill)9

Coastal management (Land-use planning ,The Port and Airport Research Institute (PARI) has beenworking for many years since the Chilean Tsunami to
mitigate tsunami disaster. Just after the Indian Ocean
Tsunami PARI established a tsunami research center todevelop new integrated countermeasures for expectedhuge tsunamis in Japan. This section explains four current
research projects at PARI:
1. Disaster prediction with ‘dynamic hazard maps’
2. Vertical evacuation in tsunami-resistant buildings
3. Real-time tsunami prediction with monitoring
4. New structural countermeasures(Tsunami gates)
5. Greenbelt

Bus Ter minal

Old Town

Figure 15 Galle city

4.1
Disaster Pr ediction with Dynamic Hazar d
Maps
People around the world were shocked by videos
taken during the Indian Ocean Tsunami attack.
Having people be aware of the danger of a tsunami
disaster is very valuable.
Figure 15 shows a map of Galle City in southern Sri
Lanka. Figure 16 shows pictures from the video
which was given to a Japanese government survey
team that visited there. The video was taken at thebus terminal and shows the tsunami attacking thearea. The tsunami came from the southeast, washedthe old market place and came into the bus terminal
area. Watching the video led me to reconsider thecurrent tsunami mitigation technologies.
1. The tsunami current on land is very strong andincludesvarious kinds of debris. Thisphenomenon was unexpected and is difficult to be
reproduced numerically in a simulation.
2. If I had been there I probably would not havebeen able to find a way to escape from the tsunami.
3. Engineers do not really understand what will
actually occur during a tsunami attack.
4. Videos and photos can be easily understood by
the public. We need the technology todisseminate images of disasters like these videos
to make people fully aware of what can occur.

Fig. 18 Large scale tsunami experimentFig. 16 Pictures from a Tsunami Video in Galle

Prediction of Tsunami DisasterTechnology for people to realize theactual figure of expected tsunami→Dynamic Hazard Maps
<Current Studies>
・Reproduction of Disaster by Physical Model Experiments
・Development of Numerical Simulation Method

Fig. 17 Studies for tsunami disaster prediction

Fig. 19 STOC calculation

10

Figure 17 explains a research project to develop tsunami disaster prediction technologies. We are conducting
model experiments and developing a new numerical simulation method to prepare dynamic hazard maps. The
dynamic hazard map is for the local people to visually understand what will actually occur during a disaster.
Figure 18 shows a model experiment to investigate the damage to an ordinary house during a tsunami attack. It
was conducted at the Large Hydo-Geo Channel of PARI measuring 184 m in length, 3.5 m in width and 12 m indepth. It was constructed in 2000 to conduct prototype wave experiments using 3.5 m waves. The wave maker
was modified to produce 2.5 m tsunamis in the channel. Various experiments are underway to investigate theactual tsunami damage to buildings and coastal facilities.

Figure 19 shows a picture
produced by STOC[12], anumerical simulation fortsunami.
STOC
cancalculate tsunami behavior
from its generation to onland run-up using 3-D
direct fluid simulation. A
dynamic hazard map canbe made with visualizationof the calculated results by
STOC.
Figure 20 shows anexperiment to examine
what
happens
when Fig. 20 Stability tests of human bodies against currents
people are caught incurrents. This was done to observe the danger ofovertopping waves from seawalls and breakwaters[13].
Figure 21 shows a result of the experiments which allow
us to identify the unstable condition due to the current andthe water level. For example, if the water level is 55 cm
and the current speed exceeds 150 cm/s, then people
cannot remain standing. The fundamental behavior oftsunami-induced current is the same as that of waves.

]

Cooperative studies should be done considering
accumulated research results on tsunami and ordinary
waves[14-19].
Fig. 21 Stability of human bodies against
currents
4.2

Ver tical Evacuation in Tsunami Resistant Buildings

The predicted Tokai Tsunami is expected to attack the coastline within several minutes. What must be
considered are the dangers to encounter the tsunami current during evacuation. As mentioned in 4.1, it is very
dangerous to walk in the inundated area. Rather than trying to escape, it could be safer to seek refuge in a tallstrong building nearby.
Figure 22 shows a temporary evacuation place for the neighborhood in Tanabe Town, Wakayama Prefecture.
People in this small community will first escape to this high land from tsunami and then to move to a large citydesignated evacuation place located more than 1 km away. At first, it would be better to evacuate to a high place
like this or a high building nearby. The temporary evacuation building should be reinforced to resist a tsunami
attack.

11

Figure 23 shows an evacuation tower in Japan. If high buildings are not available nearby, such an evacuationbuilding should be prepared or public buildings should be modified and reinforced with anti-tsunami design toprovide those in the neighborhood with shelters in case of an emergency.

Fig.22 Temporary evacuation place
Fig. 23 Evacuation tower
4.3

Real-Time Prediction of Tsunami with Monitor ing

Even if there are tsunami
warnings,
theactualGPS
satellite
tsunamis are sometimes not
Tsunamias large as predicted. If
Metersuch ”false warnings” arerepeated, the number ofDatapeople who evacuate will
decrease. Therefore, it isvery important to increase
Tsunamithe reliability of the warningby monitoring tsunamis andbasingtheirreal-time
prediction on such data.
Research is in progress to
Fig. 24 GPS tsunami meter
directly measure the tsunami
in offshore area using new
systems including pressure gauges, GPS devices and HF radars.
The Port and Harbor Bureau of the Ministry of Land
Infrastructure and Transport has a nationwide surveillance
network named ‘NOWPHAS’ to observe waves[20-22].
NOWPHAS has more than 50 stations along the Japanese
coasts with mainly ultrasonic wave gauges. NOWPHAS
has succeeded in measuring some tsunamis, but its
measurements are limited to areas relatively near the
shore. Figure 24 shows a new device called a ‘GPS
tsunami meter’ which was installed 13 km off Kochi Portand successfully measured the Tokaido-Oki Tsunami that
occurred last year. The tsunami was small but was clearlymeasured 9 minutes before arrival at Kochi Port. The
Ministry is planning to install GPS tsunami meters near
the subduction zones to have real-time prediction oftsunami.
4.4

New Str uctur al Counter measur es

In Japan, the population is very dense and economical
activities are very intensive in coastal zones. It is notenough to simply have people evacuate from the area.

12

Fig. 25 New Tsunami gatesFacilities in the coastal zones must also be protected. Hardware countermeasures such as seawalls andbreakwaters are necessary to prevent failure of vital facilities in coastline areas.
Figure 25 shows new water gates to be installed at a breakwater mouth for protection against tsunami intrusion.
They are being developed as cooperative projects with private companies. The breakwater can prevent tsunami
intrusion, and closing the breakwater mouth is very effective to reduce intrusion. A tsunami has tremendous
energy and is very difficult to stop. Therefore, it is important to develop economically feasible and technicallyeffective protective hardware measures.
4.5

Green-Belt

Damages due to the Indian Ocean Tsunami were significantly
reduced in the coastal areas protected by natural barriers ofcoastal forests. Figure 26 shows an artificial forest named‘green-belt’ to protect the coastal area behind. The artificial
forest can dissipate the tsunami energy reducing the speed andheight of tsunami. This effect is being investigated at various
institution including PARI.

5.

Fig.26 Greenbelt

CONCLUDING REMARKS

It is said that the dissemination of knowledge of tsunami is essential. This is true and we can now provide
general knowledge of tsunami to people. However the tsunami disasters are very different depending on places.
For example, to enable safe evacuation, people should be given adequate information on actual tsunami
inundation disasters, which includes the actual risk of human casualties and potential of damage to coastalbuildings and facilities, in addition to information on tsunami height. The technology to provide more specificand concrete information (scenarios) on tsunami disaster is needed. This should be done with an international
cooperation including researchers from Sri Lanka.

ACKNOWLEDGEMENTS
This paper is a modified version of the paper presented at International Symposium Disaster Reduction on
Coasts in November, 2005 in Australia. The author wish to thank professor Professor Paul Grundy of Monash
University. The author also wishes to thank Professors T. Takayama of Kyoto Univ., Professor F. Miura andK.Takimoto of Yamaguchi University, Dr. Y. Kanada, Japan Marine Science and Technology, Drs. K.Oda andK.Kumagai of National Institute for Land and Infrastructure Management for their valuable comments.
REFERENCES[1]The Investigation Delegation of the Japanese Government on Disaster caused by the Major Earthquake off the
Coast of Sumatra and Tsunami in Indian Ocean, “ The December 26, 2004 Tsunami Disaster in the Indian
Ocean – Report of Investigation-,” Earthquake and Volcanic Disaster Management, Cabinet Office, Japanese
Government, 2005, 179p.
[2]Hiraishi, T. ,”Characteristics of Tsunami Hazard in Thailand due to Off-Sumatra Earthquake,” Workshop on
Coastal Problems and Solutions, IIT Madras, 2005, pp.139-141.
[3]Fujima, K., Tomita, T., Honda, K., Shigihara, Y., Nobuoka, H., Hanzawa, M., Fujii, H., Ohtani, H., Orishimo,S., Tatsumi, M., and Koshimura, S., “Survey Results of Indian Ocean Tsunami in the Maldives,”,
Proceeding of the Special Asia Tsunami Session at APAC 2005,pp.37-48.
[4]Wijeratne, E.M.S and Pattiaratchi, C, “Characteristics of 26 Dec. 2004 and 28 March 2005 Tsunami Waves
Oscillations along the Coast of Sri Lanka,”, Proceeding of the Special Asia Tsunami Session at APAC 2005,
pp.83-92.
[5]Imamura, F., Arikawa, T., Tomita, T., Yasuda, T., and Kawata, Y.,”Field Investigation on the 2004 Indian
Ocean Tsunami in the Southwestern Coast of Sri Lanka,”, Proceeding of the Special Asia Tsunami Session at
APAC 2005,pp.119-146

13

[6]Abe, K., “Size of great earthquakes of 1837-1974 inferred from tsunami data,” Journal of GeophysicalResearch, Volume 84, 1974, p. p. 1561-1568.
[7] Kanamori, H., “Mechanism of tsunami earthquakes,” Physics of the Earth and Planetary Interiors, Volume
6, Issue 5, 1972,pp. 346-359.
[8]Tanimoto, T. , Takayama, T, Murakami, K., Murata, S., Tsuruya, H., Takahashi, S., Morikawa, M.,
Yoshimoto , Y., Nakano, S., and Hiraishi, T., ”Filed and Laboratory Investigation of the Tsunami caused by1983 Nihonkai Chubu Earthquake, ” Technical Note of the Port and Harbor Research Institute, No.470,
1983, 299p.(in Japanese)[9]Takayama, T., Suzuki, Y., Tsuruya, H., Takahashi, S., Hiraishi, T., Goto., C., Nagai, T., Hashimoto, N.,
Nagao, N., Hosoyamada, T., Shimosako, K., Endo, K., and Asai, T., “ Field Investigation f the Tsunami
caused by Hokkaido Nansei-oki Earthquake, ” Technical Note of the Port and Harbor Research Institute,
No.775, 1993, 225p.(in Japanese)[10]Tanimoto, K., “On the hydraulic aspects of tsunami breakwaters in Japan.
[11]Tsunami and Storm Surge Hazard Map Research Committee, “Manual for tsunami and strom surge hazard
maps, ”Cabinet Office, Ministry Agriculture, Forest and Fishery, Ministry of Land Infrastructure andTransport, 2002,128p.
[12]Kakinuma, T. and Tomita, T., “Development of Storm Surge and Tsunami Simulator in Oceans and Coastal
Areas, “ Proc. 29 th Int. Conf. on Coastal Eng., 2004, pp. 155.
[13]Endo, K., and Takahashi, S., “Numerical modeling of personal danger on a promenade breakwater due toovertopping waves,” Proceedings of 24th Int. Conf. on Coastal Engineering, 1994, pp.1016-1029.
[14]Iida, K, “Magnitude and energy of earthquake accompanied by tsunami, and tsunami energy, J. Earth
Science, Nagoya Univ., 6, 1958, pp.101-112.
[15]Hatori, T., “A study of damage to houses due o tsunami, Bull. Earthq. Res. Inst., Vol. 42, 1964, pp.181-191.
[16]Horikawa, K., and Shuto, N., Tsunami disasters and protection measures in Japan, Tsunami- their scienceand engineering, 1983, pp.9-22.
[17]Shuto, N., “Propagation of obliquely incident tsunamis on a step, ” Coastal Engineering Journal, vol.41,
1999.
[18]Kawata, Y., Tsuji, Y., Syamsudin, A. R., Matsuyama, M., Matsutomi, H., Imamura, F., and Takahashi, T.,“Response of residents at the moment of tsunamis, -The 1992 Flores Island Earthquake Tsunami,Indonesia,” Proc. of the IUGG/IOC Intl. Tsunami Symp., 1993, pp.677-688.
[19]Imamura, F., and Goto, C., “Truncation error in numerical tsunami simulation by the finite difference
method, Coastal Engineering in Japan, Vol,31, No.2, 1998., pp.245-263.
[20]Nagai,T., Hgawa, O., Terada Y.,.Kato, T., and Kudaka,M., “GPS Buoy Application to Offshore Wave,
Tsunami and Tide Observation,” Proc. of the 29th International Conference on Coastal Engineering, vol.1,
2004 pp.1093-1105.
[21]Nagai, T. : Development and Improvement of the Nationwide Coastal Wave Observation Network, TechnoOcean'2002, Paper-TI-1-2, 2002, 4p.
[22]Nagai,T., Satomi, S.,Terada, Y., Kato, T., Nukada, K, and Kudaka, M., “GPS Buoy and Seabed Installed
Wave Gauge Application to Offshore Tsunami Observation,” Proceedings of the 15th International Offshore
and Poler Engineering Conference, Vol.3，2005，pp.292-299.
[23]Takahashi, S, Shimosako, K., and Hanzawa M., “Performance design for maritime structures and its
application to vertical breakwaters,” Proceedings (ADMS21), PHRI, 2001, pp.63-75.
[24] Takahashi, S, Kawai, H., Tomita, T., and Takayama, T., “Proposal of real time prediction of storm surge
based on prepared scenarios,” Proc. the Third International Conference on Asia and Pacific Coasts, Korea
Society of Coastal and Ocean Engineers,2005, pp.307-310.

14

DEVELOPMENT OF DESIGN GUIDELINES FOR BUILDINGSAGAINST TSUNAMIS
W.P.S. Dias
Department of Civil Engineering, University of Moratuwa, Moratuwa. Priyan@civil.mrt.ac.lk

H.M.Y.C. Mallikarachchi
Department of Civil Engineering, University of Moratuwa, Moratuwa.

Abstr act
Three different types of structural failure were observed in various structures during the tsunami ofDecember 2004, namely sliding, overturning and undermining through scouring. Guidelines have beendrawn up for low cost single storey buildings at risk from the natural disasters of coastal flooding,
cyclones and earthquakes, covering zoning and siting issues in addition to building planning andstructural recommendations. Finally, engineering calculations have been performed for three case studies,
namely a school building that has lost a corner column due to undermining, the same school building
subjected to tsunami loading (Fig 1 & Tab 1) and a boundary wall experiencing a lateral water load. These
calculations help to identify strategies for designing efficiently against the very large effects of tsunamis.

Static Dynamic Impulsive

C

A

B

Figure 1 – Typical school building frame used for computer simulation
Table 2 – Maximum bending moment (kNm) at base for frame under tsunami loading
No. ofInfillLoading

ColumnDuration of Impulse (s)storeyswall?

width (m)position

0.1

0.25

0.50

1.0

load

1

No

0.225

Rear

10.89

12.50

13.23

13.67

14.29

2

No

0.225

Rear

15.54

20.64

22.96

24.30

24.18

3

No

0.225

Rear

17.92

23.42

26.11

27.70

28.20

2

Yes

3.10

Front

21.42

26.24

28.70

30.33

35.28

15

StaticSTRATERGIC APPROACH AND INVESTIGATIONSON MITIGATORY MEASURES

Samarawickrama SP
Department of Civil Engineering, University of Moratuwa, Sri Lanka, samans@civil.mrt.ac.lk

Hettiarachchi SSL, Ratnasooriya AHR, Welhena T
Department of Civil Engineering, University of Moratuwa, Sri Lanka, sslh@civil.mrt.ac.lk

Fernando HJS
Department of Mechanical & Aerospace Engineering, Environmental Fluid Dynamics Program, ArizonaState University, Tempe, AZ 85287-9809

1. Introduction
Post-disaster planning has been undertaken in the context of overall coastal hazards such as tsunamis,
however remote the chances of a very extreme event taking place. In particular, when planning forreconstruction it is important to assess scientifically the basis and criteria on which such an exercise isundertaken. Planning based on observations arising from a single extreme event without scientificallyanalyzing the true character of its impacts and future threats and risks should be avoided.
2. Planning Counter measures
There are many countermeasures that could be adopted in coastal zone management when planning for atsunami and other coastal hazards that accompany high waves and high inundation. These include early
warning systems, regulatory interventions in the form of extending existing setback defense line andphysical interventions such as protection structures and utilizing the full potential of coastal ecosystems.
These have to be supplemented with efficient evacuation procedures, incorporating planned evacuationroutes and structures that effectively integrate with the overall planning process.
In this respect the countermeasures can be broadly classified into two categories and respective measures arelisted below.
Countermeasures that promote successful evacuation from tsunami
1.

Early Warning Systems

2.

Public Warning Systems

3.

Hazard Maps for Vulnerability

4.

Set Back defense line

5.

Evacuation Routes and Structures

Countermeasures that mitigate the impact of tsunami

16

1.

The implementation of artificial measures for protection including tsunami breakwaters, dikes
and revetments

2.

The effective use of natural coastal ecosystems including Coral Reefs, Sand Dunes and Coastal
Vegetation (Mangrove Forests)

3.

Tsunami Resistant Buildings and Infrastructure

In the above context three types of physical interventions are identified depending on their location andfunction in protecting the coast. These interventions may be achieved not only by artificial methods via
Coastal Engineering Design but also by harnessing the full potential of natural coastal ecosystems. The typesof interventions and typical examples for each category are listed below.
(i)Reduce the impacts of tsunami waves prior to reaching the shoreline.
(eg. Tsunami Breakwaters, Coral Reefs)(ii)

Protect the coastal zone by preventing the inland movement of tsunami waves.
(eg. Tsunami Dike, Sand Dunes)(iii)

Mitigate the severe impacts of tsunami waves on entry to the shoreline.
(eg. Tsunami Dikes, Revetment, Coastal Vegetation)

On many occasions both methods can be adopted in parallel to develop well-integrated hybrid solutions
satisfying environmental concerns.
Although corals, rock reefs and mangroves are believed to provide shoreline protection against waves,currents and storm surges solid evidence for such through scientific studies is remarkably little and has beenmostly accidental or circumstantial. The paper presents the results of the physical modelling carried out tounderstand the impact of Coral Reefs and Coastal Vegetation. The experiment was carried out in a 0.8 × 1.8
× 32 m long wave tank with a programmable paddle wave generator. Figures 1 includes the normalized
velocities for the conditions of: (i) no structure, (ii) structure without an opening and (iii) structure with a

1

1

0.75

0.75

0.5

Z/H0

Z/H0

narrow opening for the testing of coral reefs for solitary waves of 2€ = 10cm,

0.25= 0.4Hz.

0.5
0.25
0

0
0

0.5

1

1.5

0

2

0.5

1

U/Uo

U/U0

(a) 50% porosity(b) 20% porosity

Figure 1: Normalized Velocity as a function of normalized height2€ = 10cm,= 0.4Hz

17

1.5

2

MITIGATING TSUNAMI HAZARDS : AN INDONESIANCHALLENGE
Subandono Diposaptono1
Deputy Director for Mitigation of Coastal Disaster and Marine Pollution,
Directorate for Marine and Coastal Management,
Directorate General for Marine, Coasts, and Small Island,
Ministry of Marine Affairs and Fisheries, Republic of Indonesia, Gedung DKP Lt.10,
Jl. Medan Merdeka Timur No 16, Jakarta Pusat, INDONESIA
E-mail: sbdn@cbn.net.id

Abstr act
The rate of population growth and magnitude of economic development along Indonesian coasts presents
many challenges. One of these challenges is to ensure the safety and security of the human population andphysical facilities that are periodically subjected to catastrophic tsunami disasters. Significant initiatives
are under way to minimize the impacts from tsunamis through better preparedness and a more informed
public.
This paper presents the implementation efforts to mitigate tsunami hazards for coastal areas and small
islands in Indonesia. Structural and non-structural counter measures were developed to mitigate the tsunami
hazard. The coastal environment is very sensitive and dynamic, therefore development of tsunami hazard
mitigation should be designed and planned based on the Integrated Coastal Zone Management (ICZM)
concept.

INTRODUCTION
Indonesia is both blessed and threatened by nature. Due to our size, extending over 3 times zones andmore than 6.000 km from east to west, and to our geologic setting, we are blessed with what is
considered by some to be the greatest marine biodiversity within a single nation. We are tasked withbeing good stewards of this global resource whose importance and management are just beginning to
be understood. This blessing is balanced by nature as we are also threatened with almost every natural
disaster known, including earthquake and tsunamis, most of which directly impact our coastal
populations and resources. Our culture has accepted this dichotomy with nature, reflecting her
diversity in our traditions and acknowledging her might during natural disasters.
One of the explanations often provided for the significant increase in the amount of disasterdamages is the population increase in disaster-prone locations, especially coastal areas. Every year,
more and more Indonesian are at risk from a variety of natural disasters that affect the coastal

18

environment. In the past 20 years, there has been such explosive growth along the nation's coastal
margins that today more than 60 % of the Indonesian population lives in coastal areas. More than 80%
of industries, 75% of cities with a population of more than 100.000 people and 60.000 villages arelocated in the coastal area. Most development activities take place in the coastal area including
fisheries, agriculture, industry, transportation, tourism, urban development, and are particularly
vulnerable to catastrophic and chronic coastal disasters, such as tsunamis.
The rate of population growth and magnitude of development along our coast presents many
challenges and a significant initiatives are under way to minimize the impacts from tsunami disasters
through better preparedness and a more informed public.

TSUNAMI DISASTER IN INDONESIA
The world was made frighteningly more aware of the danger associated with population centres
located in coastal areas by the devastating loss of live and setback of economic development due to theDecember 2004 tsunami disaster. Most of tsunamis that happen in Indonesia are caused by tectonic
earthquakes along the subduction zone and active seismic area. As recorded, from 1600 – 2005 there
were 107 tsunami events with 90% of them caused by tectonic earthquakes, 9 % by volcanic eruptions,and 1 % by landslides.
The most catastrophic tsunami was caused by the Sumatera Earthquakes 2004. The Sumatera
Earthquake (26 December 2004) generated giant tidal waves which hit coastal areas not only in NAD(Nangroe Aceh Darussalam) and North Sumatera provinces of Indonesia, but also Malaysia, Srilangka,
Thailand, India, Maldive, and Africa. Its run-ups were reported higher than 30m, and more than
300,000 lives were lost.
The 26 December 2004 Tsunami disaster in Indonesia was massive with record breaking
earthquakes and tsunami waves. There was very short almost no time for alert and evacuation.
Other examples of tsunami include Flores (1992) with more than 1950 dead, East Java (1994)
with 240 death, Biak (1996) with 107 death, and West Java (2006) with 668 death. The most famous
catastrophic tsunami was caused by the eruption of Krakatau in 1883. The Krakatau Eruption
generated giant tidal wave that hit coastal area and small islands around the Sunda Strait. Its run-ups
were reported higher than 30m, and more than 36,000 lives were lost.
Some of Indonesian coastal areas that are routinely threatened by tsunami include west coastof Sumatra, South coast of Java, North and south coast of Nusa Tenggara, islands of Maluku, North
coast of Papua, and most of Sulawesi (Celebes) coast. Table 1 shows tsunami cases in Indonesia from
1960-2005

19

Table 1. Tsunami cases in Indonesia during 1960-2005

NO

YEAR

EPICENTRUMMAX
RUN -UP(m)

TOTAL IMPACT(died/injur ed)

1.

1961

8,2 Lat. S; 122 Long.E.

NA

2 /6

2.

1964

5,8 Lat. N; 95,6 Long.E

NA

110/479

Sumatra3.

1965

2,4 Lat.S; 126 Long.E

NA

71 diedMaluku, Seram, Sanana

4.

1967

3,7 Lat.S; 119,3 Long.E

NA

58/100Tinambung South Sulawesi

5.

1968

0,7 Lat.N; 119,7Long.E

8 – 10392 died

Tambo Central Sulawesi

6.

1969

3,1 Lat.S; 118,8 Long.E

10

64/97

Majene South Sulawesi

7.

1977

11,1Lat.S; 118,5Long.E

NA

316 died

NTB, Sumbawa Island

8.

1977

8 Lat.S; 125,3 Long.E

NA

2 /25

NTT, Flores, Atauro Island

9.

1979

8,4 Lat.S; 115,9 Long.E

NA

27/200NTB,Sumbawa, Bali,Lombok

10.

1982

8,4 Lat.S; 123 Long.E

NA

13/400

NTT,Larantuka

11.

1987

8,4 Lat.S; 124,3 Long.E

NA

83/108

NTT, East Flores, P. Pantar

12.

1989

8,1 Lat.S; 125,1 Long.E

NA

7 diedNTT, P. Alor

13

1992

8,5 Lat.S; 121,9 Long.E

11,2 – 26,2

1952/2126

NTT,Flores, P. Babi

14.

1994

10,7Lat.S; 113,1Long.E

19,1

38/400Banyuwangi East Java

15.

1996

1,1 Lat.S; 118,8 Long.E

NA

3/63

Palu Central Sulawesi

16.

1996

13,7

107 died

17.

1998

2,75

34 died

P. Biak, Irian Jaya
Tabuna Maliabu Maluku

18
19
20

2000
2004
2005

0,5 Lat.S; 136 Log.E
2,02 Lat.S; 124,87
Long.E
1,11 LS; 123,5 BT
3,298 LU; 95,779 BT
2,065LU; 97,010BT

3
34,5
3,5

4 died>200.000 died
N/A

21

2006

9,4LS; 107,2BT

7,6

668

LOCATION
NTT, Central Flores

Banggai, Central Sulawesi
NAD, North Sumatera,
Nias North Sumatera
West Java (Tasikmalaya,
Ciamis), Central Java
(Cilacap, Kebumen),
Yogyakarta

POLICIES, STRATEGIES, AND OPERATIONAL BASED COASTALDISASTER IN THE COASTAL ZONE AND SMALL ISLANDS
To minimize the impact of tsunami disasters in Indonesia, nationally we always improving ourcapabilities to mitigate, and manage these events.
The Ministry of Marine Affairs and Fisheries (MMAF), Republic of Indonesia is also pro
active in minimising the impact of tsunamis on coastal communities and on aquaculture activities.
Through the Directorate General for Marine, Coasts and Small Islands, of MMAF, we are continuing
to formulate national policy and programs to mitigate the adverse impacts of tsunami disasters inIndonesia.
The program also emphasized the implementation of Integrated Coastal Zone Management(ICZM). In ICZM we will try to make a balance between the natural resources, human utilization, and20

disaster mitigation aspects (Figure 1).

NATURALRESOURCESUTILIZATIONDISASTERMITIGATION

Figure 1 - The components of ICZM (Natural Resources, Human Utilization, and Coastal
Disaster Mitigation)
Disaster mitigation is an important component that should be considered by all coastal
planners. Economic development in coastal areas that has resulted from years of effort candisappear just in a minute with a disaster such as tsunami.
Furthermore, viewing disaster risks as mainly coming from a hazard has been expanded
to include a community’s vulnerability. The shift in risk reduction strategies has, in addition to
being reactive - utilizing early warning, preparedness and emergency management tools, tobecoming more proactive - utilizing awareness raising, risk management and risk reduction
strategies. Both strategies, when combined, are expected to immensely reduce deaths, as well associal, economic and environmental losses. The framework put forth by UN-ISDR encompasses
both with sustainable development as the overarching principle. It can now be appreciated thatdisaster risk reduction and other management programmes like integrated coastal management,poverty reduction and good governance have mutually supportive objectives. As with otherprogrames, disaster risk reduction acknowledges both the social and physical dimensions of therisks, calls for a stronger political commitment and puts significant importance to changing
human behavior and attitudes. Strategies are geared towards management of the physicalenvironment (e.g., zoning, mangrove, coastal forest and habitat restoration); promotion ofsustainable livelihood, poverty alleviation and promotion of public participation.
Directorate General for Marine, Coasts and Small Islands is responsible for integrating
vertical and horizontal coastal management plans, and to support the sustainability of fisheries
development. Based on the Marine Affairs and Fisheries Policies, Directorate General of Marine,
Coasts and Small Islands will implement the four national programs. These programs were
elaborated into 8 (eight) main activities that will be implemented in our annual plan. One of theactivities is related to coastal disaster mitigation, and will be briefly explained in the following
section.

21

Structural Counter Measures
Although, Indonesia has suffered from a large number of tsunami attacks since an ancient time,
until now there is no effective countermeasures against the tsunami. Tsunami countermeasures using
hard structure (seawall, breakwater, etc) is quite expensive for Indonesian. Yet, tsunami
countermeasure using hard structure will arise aesthetical and environmental problems. Anothercountermeasure alternative is to evacuate the people who lives in the dangerous area, though it is very
difficult to persuade them to live in the high land of safety from the tsunami. Most of the people wholive in the neighbor of the coast earn their breads from fishery work, where 70 % of them are under thealeviation line. Therefore they complain of the inconvenient for their works because they have totransport for longer distance (Takayama, 1997). Even if they are forced to live in the high land, they
will finally return to the previous convenient place near sea in spite of the danger of tsunami. Throughthe study conducted by International Organization for Migration (IOM) on March 2005, showed thatmost of the refugees (72%) want to return to the previous place. The attack of tsunami is very rare likeonce 100 years. It is comprehensible that they want to take the daily convenience in spite of the veryrare danger of their lives. The other problem is in the time limitations for issuing tsunami warning.
Since Indonesia is island country, the tsunami very often attack to the coast in very short time. So there
is not enough time to warn the people.
Since the scale and hazard level of tsunami disaster depends on the population, the land usage,
and countermeasures in the affected area, the effective combination of soft structural andnon-structural countermeasures, which is suitable for the environment, social, and economic
conditions in the region should be developed. Therefore, the countermeasures should be in harmony
with daily lives of the people. Countermeasures using soft structure might be recommended in thiscase, such as mangrove green belt, coastal forest, and land use arrangement. Experimental survey
shows that green belts and coastal forests significantly reduce the tsunami energy (Hiraishi, 2000;
Harada and Imamura, 2003).
Structural counter measures using natural protection methods (soft structure), such as
casuarinas Sp plantation/green belt along the coasts for tsunamis threat are being developed. This
activity covers planting of casuarinas Sp (cemara laut), hibiscus tiliaceus (waru laut), and ketapang, .

This activity site is located on the coasts of Indonesia which experienced environmental
degradation and are located in tsunami prone coastal areas. This site was originally a pristine
forest that was then subjected to commercial cutting and conversion to settlement. These
activities led to tsunami attack.
The overall goal of the activity is to establish the greenbelt to reduce the rate of tsunami
impact. The degree or success of greenbelt in reducing the tsunami impact is not a straightforward
case as it depends on a number of factors, e.g. the distance from the tsunami and the spatial extent
and structure of greenbelt.
The concept that was developed in consultation with the community was to establish
three lines of defence :-Planting of greenbelt seedlings in coastal area, where they will be protected; and,22

-

Planting greenbelt seedlings in the beach.
Training was given to the community to educate them about how important of the forest

is both in economic and ecological aspects, and in methods of planting greenbelt seedlings.
Greenbelt are important in reducing the impacts of the Indian Ocean tsunami based on
preliminary environmental assessment, anecdotal evidence, and satellite photography before andafter the tsunami event. For example, in the Aceh coastal area, houses protected by greenbelt did
not suffer damage compared to those without greenbelt..
In the field of structural countermeasures, the Department on Marine and Fisheries had
and is doing also activities in structural mitigation by building disaster friendly houses in forms ofstage houses. All of the activities is being done through integrated coastal management.

Non-structural Counter Measures
Public awarenessEducation, training and awareness building should be considered as an integral part ofpre-disaster assessment and mitigation activities. The building of disaster awareness in thegeneral population, starting with the individual, was essential in reducing casualties. Raisingpublic awareness is achieved through various public campaign activities. Workshops are used as
the main information dissemination media, covering different target groups such as decision
makers and practitioners. The objective of this workshop are :1. To increase public awareness and knowledge.
2. To strengthen links among key agencies who are responsible for the tsunami and disastermanagement.
3. To share experiences and expertise on tsunami disaster.
4. To introduce to the people the links between the scientific value of tsunami and national plan.
5. To evaluate the progress of the tsunami monitoring system.
6. To evaluate the knowledge of the people around the tsunami prone area to the disaster.
And to complement those efforts, for children education we have published a comic bookentitled TSUNAMI. The comic was made based on the real story of local wisdom to evacuate
people in Simelue island, NAD province of Indonesia. Simelue is small island located between
2o15”-3o00” Latitude and 95o40”-96o35” Longitude, approximately 130 km southwest of
Sumatera island in Indian Ocean and about 50 km southeast of the earthquake Epicenter. Simelue
was hit by the tsunami generated from Sumatera Earthquake 2004. The tsunami wave heightvaried between 2-15m. It took 5-10 minutes after the receding of sea levels until the first tsunami
waves arrival followed by a second wave, which was the highest according to witnesses. All
villages in Alafan district on the northeast coast and facing to the source of the earthquake andtsunami were destroyed. The second wave reached maximum height of 15m. At Labuhan Bakti
villages on the south end of the island, the maximum wave height was measured at 4 m but also
destroyed all the villages.
However the toll was only 7 people dead and 1 missing from a population of 78.000

23people. There is a story that has always been told by the people of these islands about ‘SMONG”
a local word referring to a tsunami that happened in 1907. They said if you feel a quake and thesea levels drop, you should immediately run to the hills. This story saved their lives on 26
December 2004. According to historical tsunami databases, there was a tsunami in this region in
1907.
There are many ways to Rome. That is also with mitigation, many ways can be done. It isvery heavy to mitigate the whole tsunami prone coastal area in the vast Indonesia.
Prioritizing should be done for areas in the V-shape bay and river mouth because this area
will be the most suffering when the tsunami hits. The tsunami generated by a submarine
earthquake is not so big in its source, but it is amplified as it approaches to the shore. The Input
and output tsunami energy flux should be balanced each other without energy loss and supply.
Consequently, tsunami become bigger in a narrower bay. In bay of V-shape incident tsunami isalso reflected from the shores of both sides and concentrates at the intermost part of the bay.
Consequently, tsunami is amplified so much there. Well saying that the V-shaped bay isdangerous for the tsunami.
This condition is made more difficult with a mild slope topography with no protecting
greenbelt such as cemara laut, waru, ketapang, mangrove or other sea forests.
Since 2003, the Ministry of Marine and Fisheries has been advocating and socializing
tsunami in several areas, but still in the province level and district level with a not so significant
effect for the community.
Starting in the year 2006, the public awareness extends to remote bay areas and rivermouth with high population density and in prone to disaster, the method should be done moreinterestingly.
Because one of the alternative in being done through community based media i.e puppet
show, live music or other local entertain. Public awareness by using their root culture can help
them understand tsunami better. The Department of Marine and Fisheries had done outreachactivities in several areas, formally through fisherman organization, religious meeting andthrough live music entertain.
Development of Strategic planning and Spatial Use Planning Models for Provinces, Districts,
Cities and Small Islands.
The Spatial Use Planning Documents where the exist have never taken into account coastal
disaster risks. Policy for coastal spatial use planning is being developed that will incorporate
disaster mitigation measures. Strategic planning for tsunami hazard mitigation is also developed
in several cities/districts. The strategic planning consists of the following element :-Identifies issues-

Cralifies goals-

Sets detailed objectives-

Establish vision and mission-

Establish and action plan24

Development of National Policy and Guidelines.
This main activities include:
Formulating national guidelines for Integrated Coastal Zone Management
Formulating national guideline for Coastal and Small Islands Hazards Mitigation.
Formulating national guidelines for Coastal and Small Island Spatial Use Plan.
Formulating Bill for ‘Indonesian Coastal Management Act’.
The guidelines for Coastal and Small Islands hazards Mitigation are aimed at educating local
governments, and communities in disaster management. The goals of the guideline are (i) toenhance mitigation efforts in coasts and small islands, (ii) to motivate participation of local
governments, private sectors and communities in developing mitigation efforts, (iii) to promote
public awareness of disaster mitigation.

The last but not the least is our new Marine and Coastal Resources Management Program thatwill apply Integrated Coastal Zone Management Policy in 15 Provinces and 43 Districts/Cities.
The background of doing the Marine and Coastal Resource Management Project is theincrease of the ecosystem destruction and the weak organizational capacity in the local level tomanage their coastal resources after the regional autonomy. The usage of the coastal resources haslead to the widening of the decrease of the ecosystem quality (i) integrated approach in planningand managing coastal zones, (ii) information and date as basis for decision making in managing
resources, (iii) openness in the allocation of resources, and (iv) the involvement of local
government and local community in managing resources. The pressure to the coastal resources isworsen by the monetary and economical crisis. Deppletion of coastal resources and the decreaseof the quality of the marine flora and fauna has bad effects toward coastal community, especiallythe fishermen.
The MCRMP project is inserted to enhance the sustainability of the management of
the coastal resources to preserve the sea’s flora and fauna and develop social economy based on
the frame of the regional autonomy in 15 provinces. It can be reach through: (i) strengthening the
local capacity to plan and manage coastal and sea resources that sustain, (ii) increasing theavailability and access of information and city planning data with quality and various data
available for planning, (iii) enforce the law and regulation in managing the resources, and (iv)small scale investment to enhance socio economic and the quality of coastal areas in certain
location
In drafting an integrated coastal management plan, issues in natural disaster is inserted in
the national strategy of coastal management. Also the zoning plans is paying attention to disasterprone zones.
The ICZM process starts with the identification of management issues, goals and objectives(strategic plan), establishment of zonation plan, formulation of management plan, andestablishment of action plan. The coastal environment is very sensitive and dynamic, therefore alldevelopment activities should be designed and planned based on the ICZM concept because they25

can alter the stability of fragile ecosystems, change the socio economic situation, and havenegative impacts. The ICZM concept will include disaster mitigation in the hierarchial planning
process. In this program, a risks and hazards thematic map including tsunami is being developedin 15 Provinces.
A hazard map was developed using technical data from the historical data and numerical
forecasting of tsunami. All information was translated to the GIS platform, significantly refining
areas which could easily be inundated and where specific households, in times of emergencies,
need to be evacuated immediately. They now use GIS as an effective tool for upland and urban
planning; and on the drawing board are plans for appropriate coastal zone development.
Tsunami hazard map shows the information necessary for residents to take refuge to highplace or shelters alocated by local government. The tsunami hazard map usually indicates theinundation area, infrastructure, land use, evacuation route, and location of safety places. An
example of tsunami hazard map is shown in Figure 5, which is for Padang city, West Sumatera
Province. The map is given by one sheet of paper, of which shows the tsunami inundation state inwhole city. The map has been completed after several discussions with stakeholders.

Figure 2 - Tsunami Hazard Map in Padang City, West Sumatera Province of Indonesia

Tsunami Resear ch in Indonesia
Research is fundamental to tsunami disaster mitigation strategies. Recent research
agendas have become multidisciplinary, which look not only at comprehensive knowledge about
disaster, but also on their likely impacts to societies and how communities interact and findsolutions given knowledge of potential disasters affecting them. Research data are important
inputs that drive policy directions and significantly affects how governments formulate informed
decisions.

It also feeds into the other components of tsunami disaster mitigation such as

26

continuing education, public awareness, advocacy and information management.
After the 1992 Flores Tsunami, scientists in Indonesia became involved actively intsunami research. Several tsunami surveys and laboratory work have been done in Indonesia. An
International Tsunami Survey Team with experts from Indonesia, USA, Japan, UK, Korea, andother countries surveyed the 1992 Flores Earthquake Tsunami, 1994 East Java Earthquake
Tsunami, 1996 Irian Jaya Earthquake Tsunami, 2004 Sumatera Earthquake Tsunami and 2006
West Java Tsunami. They gathered data of maximum tsunami run-up heights, and distances,
average run-up height and areas of inundation, flow pattern of run-up and run-down, eyewitness
accounts, and observations of subsidence and uplift. Therefore, the tsunami data was wellreported and documented for these events. They also performed investigation both by numericalmodeling and physical modeling e.g. tsunami generation, propagation, and run-up; effect ofmangrove greenbelt to reduce tsunami etc. Many agencies and universities in Indonesia havedone tsunami research, including-

Bandung Institute of Technology (ITB), Bandung-

Sepuluh Nopember Institute of Technology (ITS), Surabaya-

Gadjah Mada University (UGM), Yogyakarta-

Hasanudin University (UNHAS), Makasar-

Agency for Meteorological and Geophysics (BMG)-

Geological Research Development Center (PPGL)-

Agency for the Assessment and Application of Technology (BPPT)-

Ministry of Public Work-

Ministry of Marine Affairs and Fisheries (MMAF)-

Ministry of Energy and Mineral Resources.

Establishment of Indonesia Tsunami Ear ly-War ning System
Early warning saves lives. That’s a very obvious lesson from the tsunami event. Early
warning systems are considered the foundation of disaster mitigation. With the advances inscience and technology, accurate forecasting of the occurrence of a natural hazard has saved
thousands of lives and protected properties. It is very unfortunate indeed that the Indian Ocean
lacks a tsunami warning system like the one installed in the Pacific.
Indonesia is prepared and committed to develop and manage a National Tsunami Early
Warning System (TEWS) as part of the Regional Indian Ocean TEWS. Indonesia has designed
framework that will be used for establishing an effective and durable Indonesian TEWS on
national scale which could provide a tsunami warning in less than 5 minutes whereverearthquakes occur.
a. Strengthen the Indonesian TEWS to function as a regional TEWS for Indian Ocean.
b. Increasing Public awareness and preparedness in the disaster affected regions.
c. Encourage and facilitated the capacity building of national research institutions in
disaster mitigation.
The basic principles of the Indonesian TEWS are as follows :27

a. Issue warning within 5 minutes.
b. Real time, automatic, and compatible with national and international standard.
c. The components are : observation and integration of data; dissemination of information;and community preparedness.
MMAF is also involved in the working group for preparing TEWS. The team is coordinated by
the Ministry of Research and Technology.

Integr ated Coastal Zone Management Law, Indonesia’s New Beginning
The effort to optimize the management of coastal and resources should be supported
by regulation, especially those related to the setting of coastal and environmental environment.
The support of a regulation is hoped to be able to harmonize inter sector and inter area policies tocreate equality between usage aspects and conservation aspects. In this regards, the Department ofMarine and Fisheries has initiated to make a draft bill on coastal and small island management.
The document that is ready is the white paper of the coastal management law and will be handed
over to the parliament using their initiatives right.
The goal of the law is to:(a) protect, conserve, rehabilitate, use and manage coastel resources based onsustainability; (b) Enhance the management of coastal resources through integration,
coordination and delegating authority (c) Restore and enhance community based coastal resouce
management and (d) law inforcement
The key of a successful sustainable management lies in the ability of the community andthe local government to plan and use the coastal resources as needed. The community means that
it is not totality the rights of the government but how they can represent the interest of the public.
More widely, community are all primary stakeholders that is involved in the management processof resources as a system. Based on those premises, generally there are three focuses of the draft
bill: (i) pushing communities and local government initiatives to manage their coastal resources
based on sustainability and voluntarily; (ii) having a standard in coastal management in the nation
wide level, such as the management of coral reef ecosystem and what is associated with it; and(iii) organizing mandatory management such as resolving conflict and law enforcement.
First, to certify the program and giving voluntary incentive, the draft will regulate thevoluntary action of local government to follow or not follow the program. The initiative has tocome from the local government or community, not top down. For interested areas, they can drafta coastal management plan and propose it to the Bappeda/Local Government of Fisheries andMarine to be certified in the district or provincial level. Those ho had been certified voluntarily tohave the coastal management program will be given proper incentive. There are two main fundsource for the incentive: MMAF has allocated part of its budget to implement the integrated
Coastal and Small Island Management program. The government can use their national budget
for a project revolving fund. The source of fund will relatively be small and not efficient as agovernment incentive for the local government.

28

Second, the norms of coastal, small island, and the management of the ecosystem isregulated by its own standard that is in the fourth part of the law draft. One of the management
strategy is to give opportunity for damaged nature to rehabilitate naturally, and also preserving
the other ecosystem. So that the damaged coral and seagrass due to destructive fishing can berehabilitate, letting the fishes procreate in the area.
The third, enhancing effectiveness in managing coastal area should be done with the role ofall stakeholders in conflict resolution, monitoring, supervision and law enforcement. Those who
made destruction should be punished, law enforcement should be done consistently and correctlybased on the existing regulation. Monitoring activities will push compliance and law enforcement
openly, whereas the community is participating as ‘reef watchers’ and private sector will get thebenefits by also funding the activities of monitoring and supervising and enforcement.
In the bill draft, articles on mitigation has been included, those physically and structurally.
The Sumatera 2004 earthquake and tsunami were a rude awakening from a long sleep inIndonesian coastal management systems. They shook us to the realization of how exposed we are
to various disasters. They demonstrated how vulnerable Indonesia is to socio economic impacts
of disasters, and that our capacity is simply to low to meet the ever increasing challenges. One
element is the creation of a Integrated Coastal Zone Management Law which include tsunami andother coastal hazards.
The Indian Ocean tsunami will create a shift in coastal management paradigm. We havelearnt coastal management principles from mid-latitude countries, but seldom in relation tonatural hazards. In tropical coastal management, we must now include tsunamis and other coastal
hazards. In relation to reducing the risks, integrated coastal management (ICM) needs tore-examine the role of the coastal ecosystems in relation to aquaculture and paddy cultivation,
selective development of beaches and islands for tourism, appropriate design criteria and setbacklines for tourist infrastructures, marine parks for the protection of coral reefs, etc.
It is true that the law alone would not prevent tsunamis from devastating our shores,
prevent deaths, on halt economic damages. The law would – however - provide the legal
foundation and legitimacy for our government to undertake the necessary steps to reduce the scaleof disasters in coastal area, and thus to extend better protection to its people.
The coastal management bill would require among others: a) to enforce regular hazards
identification, assessment, and monitoring; b) to mitigate the hazard of disasters; and c) to ensure
the preparedness of community and emergency responders.
With regard to enforcement, the Bill set sanctions for violation of its regulations, it
imposes penalties and punishments for faults by omission and by commission, and it even enables
people to file lawsuits against government and other entities in relation to protection and disasterrisk matters.
The Draft Bill were presented to the House’s Plenary and, the House established aSpecial Commission to bring the draft bill into the political processes. It has been resolved that theBill will be approved by the House, to be, referred to the Executive Branch, and to be signed off
before the end of 2007.

29

REFERENCES
Harada, K. and F. Imamura (2003). Studi on The Evaluation of Tsunami Reducing by Coastal Control
Forest for Actual Conditions. Proc. 2ND Int. Conf on Asia and pacific Coasts, Chiba, Japan.
Isobe, M (1995). A theory of Integrated Coastal Management in Japan.
Hiraishi T. (2000) Proceedings of the 3th Multi-lateral Workshop on Development of Earthquake andTsunami Disaster Mitigation Technologies and Their Integration for the Asia-Pacific Region(EqTAP), EDM, November 2000.
Pujiono P. (2005). Disaster Management National Law, Indonesia’s New Beginning, Workshop on
Mitigation, Preparedness, and Emergency Response to Tsunami in Coastal Areas, Jakarta, May
2005.
Subandono, D (2002), Coastal Disaster in Indonesia and Its Perspective, Wokshop on The
Development of Integrated Disaster Reduction Systems on Compound Urban Floodings,
Disaster Prevention Research Institute (DPRI), Kyoto University, Kobe. 2002.
Subandono, D (2003), Tsunami Disaster Mitigation in the Context of Integrated Coastal Zone
Management in Indonesia, Sixth Multi Lateral Workshop on Development of Earthquake andTsunami Disaster Mitigation Technologies and Their Integration for the Asia-Pacific Region(EqTap), Earthquake Disaster Mitigation Research Center (EDM), RIKEN, Ise-Kashikojima,
Japan, 2003.
UN-ISDR. (2004). Living with risk – A global review of disaster reduction initiatives. Inter-Agency
Secretariat of the International Strategy for Disaster Reduction.

30

Effect of Tsunamis on the Easter n Coast of Thailand

Anat Ruangrassamee
Department of Civil Engineering, Chulalongkorn University, Thailand, fcearr@eng.chula.ac.th

Nopporn Saelem
Department of Civil Engineering, Chulalongkorn University, Thailand

1. Introduction
The infrastructures in the Gulf of Thailand, for example, gas pipelines and platforms can be affected bytsunamis that are generated by earthquakes in the western part of the Philippines. In this study, thesimulation of tsunamis in the Gulf of Thailand is conducted to obtain the arrival time, wave height, andcurrent velocity.
2. Analytical Conditions
Six cases of fault ruptures are considered for earthquakes with magnitudes of 8.0, 8.5, and 9.0
corresponding to earthquake return periods of 63, 205, and 667 years, respectively. The linear shallow
water wave theory in spherical coordinate system is used for tsunami simulation in the large area covering
Southeast Asia while the nonlinear shallow water wave theory in Cartesian coordinate system is used fortsunami simulation in the Gulf of Thailand.
3. Analytical Results
From the simulation of the tsunami generated by the Mw 9 earthquake, the tsunami arrives Narathiwat in
11 hrs, Trat in 15 hrs, Prachuapkhirikhan in 16.5 hrs, Phetchaburi in 19 hrs, and Bangkok in 20 hrs. It isfound that the arrival time is slightly affected by the earthquake magnitude.
For an earthquake magnitude of 9.0, the tsunami height is 0.97 m at a sea depth of 4.4 m and thecurrent velocity is 0.27 m/s at a sea depth of 15.6 m in Narathiwat. And the tsunami height is 0.38 m at asea depth of 5.4 m and the current velocity is 0.15 m/s at a sea depth of 17.5 m in Trat. At the central
coast of Vietnam, the tsunami height is 3.8 m and the current velocity is 1.7 m/s at a sea depth of 20 m.
The large difference of tsunami height and current velocity is due to the diffraction of waves into the Gulfof Thailand.
The effect of earthquake magnitudes on tsunami height and current velocity is investigated (Figure1). As the earthquake magnitude increases from 8.0 to 8.5, the tsunami height increases by 3 times and thecurrent velocity increases by 2 times. And when the earthquake magnitude increases from 8.5 to 9.0, thetsunami height and the current velocity increases by 2 times. It is obvious that the earthquake magnitude
significantly affects tsunami height and current velocity.

31

4. Conclusions
The tsunami arrival time, wave height, and current velocity are analyzed in this study. The Gulf ofThailand is less affected by the tsunamis generated by fault ruptures off-shore the Philippines. The effectis lessened by the diffraction of tsunamis at the southern part of Vietnam. However, lifeline facilities in
the Gulf of Thailand should be well prepared for the disaster.

References
Baulista, B. C., Baulista, M. L. P., Oike, K., Wu., F. T., Punongbayan, R. S. (2001): A new insight on thegeometry of subducting slabs in northern Luzon, Philippines,” Tectonophysics, 279-310.
General Bathymetric Chart of the Oceans (GEBCO) (accessed in 2006):
http://www.ngdc.noaa.gov/mgg/gebco/grid/1mingrid.html

Figure 1: Current velocity from the Mw 9 earthquake

32

EFFECTS OF TSUNAMIS ON MOORED & MANUEVERINGSHIPSJohn R. Headland, PE, Moffatt & Nichol, jheadland@moffattnichol.com
1. Intr oduction
The Boxing Day Tsunami of 2004 impacted at least two major commercial harbors, namely Colombo in Sri
Lanka and Chennai in India. While the impacts of the tsunami on the ports were not significant, the event
highlighted the threat that tsunamis pose to moored and maneuvering ships. Specifically, maneuvering ships inboth harbors were overpowered by velocities produced by the tsunami and ships were broken from theirmoorings at Chennai (Figure 1). The author has been involved in evaluating the potential impacts of tsunami
events on the Ports of Los Angeles and Long Beach in Southern California, USA. This paper presents methods
for examining the impact of tsunamis on moored/maneuvering vessels.

Figure 1- Moored Vessel During Tsunami, Port of Chennai, India
The approach taken here is to use harbor hydrodynamic results to force mooring and maneuvering dynamic
models. The TERMSIM model was used to simulate mooring dynamics, the SHIPMA model, maneuvering
dynamics.
2. Analysis
Moored vessels are subject to three physical phenomena during a tsunami: (1) vertical lifting of the vessel due torise in water level (VWL) which cannot be accommodated by typical mooring line arrangements, (2) horizontal
forces due to accelerated currents (HAC) which can be quasi-static or dynamic, and (3) dynamic horizontal
forces from leading tsunami waves (HLW). While HLW loads can be approximated by the HAC approach,more research is necessary to fully develop the HLW case. An example static VWL analysis of the mooringarrangement in Figure 2 is presented below for a typical Post-Panamax container ship in Figure 3 which showslines will part with 3-4 m tsunami heights.
Dykstra et al (2006) report tsunami modeling results for the Port of Long Beach and Los Angeles. Figure 4
shows, for a hypothesized Palos Verde landslide scenario with an approximate return period 10,000 years, thatthe maximum tsunami height at any berth location in the port complex is 3m or less with the exception of a very
isolated area. Thus a very small portion of the berths would be vulnerable to excessive VWL.

Figure 2. Typical Mooring line Arrangement for a Post-Panamax Container Ship.

33

Figure 3. Mooring Line Analysis For Various Tsunami Heights (VWL).
Water Level
7.0

6.5

6.0

5.5

5.0

(Units in kilometer)

4.5

4.0

3.5

3.0

2.5
Water Level [m]Above 7
6.5 - 76 - 6.5
5.5 - 65 - 5.5
4.5 - 54 - 4.5
3.5 - 43 - 3.5
2.5 - 32 - 2.5
1.5 - 2
1 - 1.5
0.5 - 10 - 0.5
Below 0Undefined Value

2.0

1.5

1.0

0.5

0.0
0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5
5.0
5.5
(Units in kilometer)

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

Figure 14. Tsunami Height Within the Ports of Los Angeles and Long Beach For A Hypothetical Event.

Ship motions were computed using the TERMSIM model developed by MARIN. While not developed fortsunami analysis (it cannot simulate a rapid rise in water level), it can perform a full dynamic analysis of thetsunami-induced currents. The same vessel/mooring arrangement used above was modeled here. The
hypothetical tsunami currents were not sufficient to part the mooring lines.
Experience indicates that accelerated tsunami-induced currents pose very considerable threat to maneuvering
vessels as well as vessels that have broken from their moorings. The SHIPMA maneuvering model developedby MARIN was used to demonstrate the impact of tsunami currents. For the case of LA/LB, tsunami currents
were not sufficient to cause a vessel passing through one of the harbor entrances to lose significant control.
3. References
Dykstra, D.H., and W. Jin. Detailed modeling of locally generated tsunami propagation into the ports of Los
Angeles and Long Beach, 30th ICCE, ASCE.
TERSIM, MARIN, The Netherlands
SHIPMA, MARIN, The Netherlands

34

Advanced ocean floor networ k for ear thquakes and tsunamis ar oundthe Nankai Trough in Southwester n J apan
- Towar ds the under standing of mega-thr ust ear thquakes -Yoshiyuki Kaneda
Marine Technology Center, Japan Agency for Marine-Earth Science and Technology, Yokosuka,
Kanagawa, Japan, kaneday@jamstec.go.jp

Katsuyoshi Kawaguchi*, Eiichiro Araki*, Hiroyuki Matsumoto*, Takeshi Nakamura*,
Shinichiro Kamiya*, Takane Hori**, Toshitaka Baba***Marine Technology Center, Japan Agency for Marine-Earth Science and Technology**Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology

In many researches focusing on the mega-thrust earthquakes around the Nankai Trough in southwesternJapan, the structural researches using refractions and reflections seismic has succeeded to image the key
structures to understand recurrences of mega-thrust earthquakes around the Nankai Trough. Moreover,results of earthquake recurrence cycle simulation show that the first ruptures seems to occurred aroundthe Tonankai earthquake rupture zone in each recurrence cycle, and the clear segment boundary between
the Tonankai and Nankai earthquake rupture zones off the Kii peninsula was analyzed using tsunami data.
The 1944 Tonankai and the 1946 Nankai earthquakes, each hypocenter was located off the Kii peninsula.
So, imaged irregular structures seem to be as key structures at the segment boundary between the
Tonankai and Nankai earthquake rupture zone. By the advanced simulation study of recurrence cycles ofmega-thrust earthquakes around the Nankai Trough, these irregular structures seem to act as a controllerof recurrence cycle and pattern of mega-thrust earthquakes in the Nankaki Trough.
Based on these researches, we proposed and have been starting to deploy the dense ocean floor
observatory network system equipped with multi-kinds of sensors such as seismometers, pressure gauges
etc., focusing on the understanding of crustal activities off Kii peninsula including the Tonankai/Nankai
earthquake rupture zones.
This observatory system will be the one of most advanced scientific tools to understand the mega-thrustearthquakes around the Nankai Trough.
This advanced dense ocean floor observatory network system has useful functions and purposes asfollows,
1) Redundancy, Extension and advanced maintenance system using the looped cable system, junction
boxes and the ROV/AUV etc.
2) Speedy evaluation and notification for earthquakes and tsunamis earthquakes and tsunamis.

35

Especially, these are most important functions for disaster reduction of earthquakes and tsunamis.
3) Provide observed data such as ocean floor deformation derived from pressure gauges to improve thesimulation and modeling researches about the mega-thrust earthquakes
4) Understanding of the interaction between the crust and upper mantle around subduction zone. In thispaper, we will explain the advanced dense ocean floor observatory network system in detail andemphasize the purpose and importance of this system.
In this presentation, we would like to introduce this advanced ocean floor network system in detail.

36

TSUNAMI WARNING SERVICE IN J APAN

Yuji Nishimae
Japan meteorological Agency, Chiyoda-ku, Tokyo, Japan, nishimae@met.kishou.go.jp

1. Introduction
Japan is located in the circum-Pacific tectonic zone where seismic activity is extremely high. Morethan ten percent of earthquakes in the world take place in and around Japan. Japan, surrounded by seas, is
one of the most tsunami-prone countries in the world, and has suffered from serious tsunami disasters.
Considering such circumstances, the Japan Meteorological Agency (JMA) initiated tsunami warning
service for local tsunamis in 1952, and that for distant tsunamis in 1962.
2. Procedure for issuance of tsunami war r ing/advisor y
JMA continuously monitors seismic activity in and around Japan. When a large earthquake occurs
in/around Japan, JMA immediately determines the hypocenter and the magnitude of the earthquake. If theearthquake occurs in ocean area with tsunamigenic potential, JMA conducts the tsunami forecast
operation using the database containing tsunami amplitude and travel time constructed by numericalsimulation. Tsunami forecasts are categorized into two: Tsunami Warning and Tsunami Advisory.
Tsunami Warning is divided into two grades: Major Tsunami and Tsunami, depending on the estimatedamplitude of the tsunami as shown in Table 1. JMA issues Warnings and/or Advisories for 66 coastal
regions which cover all of coastal areas of the country. These tsunami forecasts contain the estimatedmaximum tsunami amplitude and estimated tsunami arrival time. JMA provides Warnings and/or
Advisories for the national and local authorities for disaster prevention and broadcasting stations.
Governors of municipalities are responsible for giving their residents directions to evacuate from tsunami
hazardous areas. Warnings and/or Advisories are cancelled when JMA concludes that the dangerous
situation is over, namely, when the observed amplitude of the tsunami diminishes and becomes lower.
When a large earthquake occurs distant from Japan, JMA also determines the hypocenter andmagnitude using seismic data from global seismological observation network as well as domestic ones,
and exchanges information on the earthquake with PTWC and USGS. In case there is a possibility oftsunami generation, JMA immediately conducts the tsunami forecast operation in the same manner andcriteria as the local tsunami procedure.

Table 1: Types of Tsunami Forecast Bulletin
Tsunami Forecast Bulletin
TsunamiWar ning
TsunamiAdvisor y

Value of Tsunami Amplitude to be issued

Major Tsunami"3m", "4m", "6m", "8m", "over 10m"

Tsunami"1m", "2m"

Tsunami Attention"0.5m"(Tsunami amplitude is measured from the ordinary tide levels)37

3. Application of advanced technologies for tsunami war ning
For advance actions to mitigate damages caused by strong motions of earthquakes, JMA has built the"Earthquake Early Warning" system (EEW system), which quickly determines the hypocenter and themagnitude from the seismic waveform data observed at the seismic stations near the hypocenter, andtransmits warning with estimated seismic intensity and arrival time of strong ground motion at eachregion before the strong ground motion arrives as possible. This technique is also expected to contributeto reducing elapsed time for the issuance of tsunami warning. JMA applies EEW technique to tsunami
warning to be issued in 2 minutes at earliest after the occurrence of the earthquake.
Previously it was technically difficult to derive earthquake mechanisms quickly after occurrence of anearthquake. Therefore, JMA assumed reverse faults with dip angle of 45 degree, which generate tsunami
most efficiently, in order to make the tsunami database for local tsunami warning operation to ensure
disaster prevention. Now, JMA developed a new system to calculate Centroid Moment Tensor (CMT)
solution automatically about 10 minutes after an earthquake occurrence in order to use them for tsunami
forecast. However, it is not available for the first warning, which is issued 3 to 5 minutes after theearthquake occurrence. Therefore, JMA will apply it to re-evaluating the grade of the warning based on
the derived CMT solution. JMA will start to use the CMT solutions for tsunami warning operation soon.
4. Nor thwest Pacific Tsunami Advisor y and Tsunami Watch Infor mation for the Indian Ocean
In the Pacific Ocean region, the earthquake of magnitude 9.5 occurred near Chile in 1960. The tsunami
generated by the earthquake caused disasters to many countries around the Pacific Ocean. As a lesson of
the tsunami disasters, International Coordination Group for Tsunami Warning System in the Pacific(IGC/ITSU), which was renamed to Intergovernmental Coordination Group for the Pacific Ocean
Tsunami Warning and Mitigation System (ICG/PTWS) in 2005, was established in 1965. Pacific Tsunami
Warning Center at Hawaii is responsible for the provision of tsunami warning for the whole Pacific region
to member states of ICG/PTWS. In addition to that, establishment of the regional tsunami warning centerhas been discussed by ICG/ITSU since 1978. JMA established the Northwest Pacific Tsunami Advisory
Center (NWPTAC) as the regional center in the Northwest Pacific region and started to provide tsunami
advisory to countries around the Northwest Pacific Ocean in March 2005. The 2004 Sumatra earthquake
and the tsunami caused unprecedented disasters in the Indian Ocean region. Intergovernmental
Coordination Group for the Indian Ocean Tsunami Warning and Mitigation System (ICG/IOTWS) as wellas the Pacific Ocean region was established in 2005 and discussion for establishment of tsunami warning
system has been continuing. Therefore, JMA has been providing countries around the Indian Ocean with
Tsunami Watch Information (TWI) on an interim basis since 2005, and will continue until tsunami
warning system will be fully operated in the Indian Ocean region in order not to repeat such disasters.
When an earthquake of magnitude 6.5 or greater occurs in the coverage area, NWPTA or TWI isprovided to relevant countries in 20 to 30 minutes. NWPTA and TWI contain source parameters,
evaluation of tsunamigenic potential and estimated tsunami arrival times or travel times. Moreover,
information with regard to estimated tsunami heights is also provided in NWPTA. When a tsunami isactually observed at tidal stations, information on tsunami observations is subsequently provided.

38

HYDRAULIC CHARACTERISTICS OF BUOYANCY-DRIVENVERTICAL PILING BREAKWATER

Taro Arikawa
Port and Airport Research Institute, Yokosuka, Kanagawa, Japan, arikawa@pari.go.jp

Fumitake Nakano
Port and Airport Research Institute, Yokosuka, Kanagawa, Japan, nakano-f89s9@pari.go.jp

1. Introduction

A breakwater must protect a harbor from rough sea damage while allowing ships to moor insafety. But it has been very difficult to guarantee calm water in the harbor because the entry
route of fairway is always open. So, new innovative breakwater is developed, that is always at
the bottom of the sea, and surfaces at times of high waves, storm surges and tsunamis, as needed
to protect the inside of the harbor.
The new breakwater is a wall structure that is formed by upper and lower steel piles (seeFigure 1). There is the slit between two piles structurally.
Compressed air is supplied from the bottom of the lower pile into the upper pile. The upper pilerises to the surface because of the relative increase in buoyancy. When air is expelled from theupper pile, its buoyancy drops causing the upper pile to sink back into its resting position.
This research investigates hydraulic characteristics of this breakwater by using the large-scale
experiments and numerical simulations and reports the development project.

Deadweight > Buoyancy

Completion of set-up

Excess Buoyancy

Midway to surface

Compressed airCompressed air

Before to surface

Deadweight < Buoyancy Deadweight = Buoyancy

Figure 1 - Concept of the new breakwater
2. LARGE SCALE EXPERIMETS
The 1/5 model scale tests was conducted in the Large Hydro-Geo Flume. This wave flume is 184m long,
12m deep and 3.5m wide. The stroke of this wave flume is 14m. 7 Steal piles, which diameter is 40cm,
were set up in the flume (see Photo 1).

The pressures on the piles, velocity in the slit and height of waves are measured while changing
the distance of the opening. The wave period is changed from 3.6s to 26.8s and the wave heightis 0.4m and 0.8m. Figure 2 shows the transmission coefficient of one case. The result shows thatthe transmission coefficient is 0.4 to 0.6 when the ratio of the opening distance to diameter and39

indicates that the coefficient is not depend at the wave period. Pressures on the piles andvelocity in the slit are also measured.

Photo 1 – Experimental set up
×波高0.8m，周期25.0s，水深2.0m
HTD△波高0.4m，周期26.8s，水深2.0m
HTD○波高0.8m，周期20.1s，水深2.0m
HTD□波高0.8m，周期25.8s，水深2.5m
HTD＊波高0.8m，周期5.40s，水深2.0m
H
T
D
H
T
◇波高0.8m，周期3.60s，水深2.0m
DH＋波高0.8m，周期5.40s，水深2.5m
T
D

1.2

transmission
coefficient
波高伝達率

1.0
0.8
0.6
0.4
0.2
0.0
0

0.05

0.1

0.15

0.2

開口率to diameter
Ratio of opening

Figure 2 - Results of transmission coefficient
3. NUMERICAL SIMIULATIONS

3 dimensional Navier-Stokes Numerical simulator is developed to evaluate the velocity andpressure on the piles. The results of this simulation are good agreement with the results ofexperiments.
By using these results, this simulator applied to the locale with lager grid size. Figure 3 shows
the comparison of Tsunami height in the Wakayama shimotsu port due to Tokai, Tonankai andNankai earthquakes. The right hand side figure is installed the buoyancy-driven vertical pilingbreakwater at the mouse of the port. This result shows that this new breakwater decreases
Tsunami height and inundation area. This breakwater delays the inundation time for fiveminutes in this case.

without new breakwaterwith new breakwater
Figure 3 - Comparison of Tsunami height40

NUMERICAL SIMULATION OF INDIAN OCEAN TSUNAMI
USING LINEAR AND NONLINEAR DISPERSIVE WAVE THEORY

Koji Fujima
National Defense Academy, Yokosuka, Kanagawa, Japan, fujima@nda.ac.jp

Yoshinori Shigihara
National Defense Academy, Yokosuka, Kanagawa, Japan, shigi@nda.ac.jp

Takashi Tomita
Port and Airport Research Institute, Yokosuka, Kanagawa, Japan, tomita@pari.go.jp

Kazuhiko Honda
Port and Airport Research Institute, Yokosuka, Kanagawa, Japan, honda@pari.go.jp

1. Introduction
In tsunami propagation over a long distance on a deep sea, the frequency dispersion effect plays animportant role in the wave transformation. In addition, if the wave propagates on a long shallow shelf,
soliton waves are generated by the interaction between nonlinearity and dispersion effect. The authors(2006) had performed the numerical simulation of the Indian Ocean Tsunami, and made clear that thefrequency dispersion effect was appeared significantly in the southwest direction of the tsunami source.
This conclusion suggests that the dispersion effect is not important in the numerical simulation of the
Indian Ocean tsunami in Sri Lanka. However, the simulation of the previous work had ended at 6 hours
after the earthquake, although the reflected wave from the Maldives attacked Sri Lanka 5 hours after theearthquake. In the present paper, the new simulation, in which the reproduction time is set as 8 hours, isconducted to check the contribution of the dispersion effect on the reflected waves from the Maldives. In
addition, the effect of the nonlinear dispersion is examined in the shallow water area in the southwest
coast of Sri Lanka.
2. Numer ical Method and Condition
The numerical procedure is same as the previous work (Shigihara and Fujima, 2006). The initial condition
and the bathymetry data are same as those used by Tomita and Honda (2006). However, the reproduction
time is set as 8 hours.
3. Results and Discussions
The time history of water surface elevation at h=10m point is recorded at some locations along thesouthwest coast of Sri Lank drawn in Figure 1 (P1 to P6). The result at P1 and P4 is shown in Figure 2
and 3, respectively.

41

At P4, the leading wave is the maximum wave, and the third wave is the maximum at A1. Thisdifference may be caused by the topography effect. In addition, at P4, the waves after 4 hours from theearthquake have the short wave period; however the long-period waves are appeared after 6 hours after
the earthquake at P1. The long-period waves 6 hours after the earthquake recorded at P1 are the reflected
waves from the Maldives. These waves propagated the long distance, although the numerical result by thedispersive wave theory is very similar to that by the long wave (non-dispersive) theory. Thus, it isconcluded that the dispersion effect is not important in the numerical simulation of the Indian Ocean
tsunami in Sri Lanka, even if the reflected waves from the Maldives have an important role in the tsunami
waveform in Sri Lanka.

Figure 1: Output Point and bathymetry off the southwest coast of Sri Lanka.

Figure 2: Water surface elevation at P1.

Figure 3: Water surface elevation at P4.
References
Shigihara, Y. and K. Fujima (2006): Dispersion effects in the Indian Ocean Tsunami, Ann. J. Coastal Eng.,
Vol. 53 (1), pp. 266-270. (in Japanese)
Tomita, T. and K. Honda (2006): Basic study on numerical analysis of the 2004 Indian Ocean Tsunami in
Sri Lanka, Ann. J. Coastal Eng., Vol. 53 (1), pp. 251-255. (in Japanese)

42

STRUCTURE-STRUCTURE IMPACT MODELINGFOR TSUNAMI DEBRIS FLOW

Solomon C. Yim
Coastal and Ocean Engineering Program, Oregon State University, Corvallis, Oregon, USA,solomon.yim@oregonstate.edu

Gang

Cao

Coastal and Ocean Engineering Program, Oregon State University, Corvallis, Oregon, USA,
caoga@engr.orst.edu

Abstr act
In a large tsunami, sea or land-based structures such as boats, barges and vehicles may become debris thatflow with the tsunami in land. Video footages from the 2004 Indian Ocean Tsunami clearly showed that
potential damages on coastal structures such as resort hotel buildings and highway bridges close to theshoreline due to debris flow may be significant. Additional evidence include photographs of boats, barges
and vehicles found kilometers in land in Indonesia, India, Sri Lanka and Thailand. The large amount ofdebris (boats and vehicles) on Okushiri Island after the 1993 tsunami is but another collaboration ofdebris flow occurrence. Thus, in predicting tsunami effects tsunami on coastal structures, it is important totake into account the associated debris flow and impact of large (flexible) objects. This paper focuses on
the modeling of structure-structure impact behavior in free-surface flow and addresses some issues
including:•Interaction between boundary layers around the structures for both low and high Re flows•

Cavitation occurrence in high Re flow•

Free surface interaction with structural boundary layers•

Free surface interact with cavitation

V2
V1

Fig.1. Basic model for Structure-Structure Impact

43

The Basic model, shown in Fig.1, represents two flexible structures moving in opposite direction in thefluid medium with free surface and bottom wall. The fluid domain can be described by the Navier-Stokes
equation (NSE) or Reynolds-Averaged Navier-Stokes (RANS) equation with k-epsilon closure model.
The near wall region of the flow containing the structures can be sub-divided into three different regions.
Due to the complexity of the buffer layer and defect layer, there is currently no general method for
applying a turbulence model with the first computational interior node located in these layers. Instead, thecommonpractice is to place the first near-wall node either in the viscous sub-layer(Low-Reynolds-Number (LRN) models), or in the inertial sub-layer (High-Reynolds-Number (HRN)models). For the LRN turbulence models, which use a refined mesh close to the wall, damping functions
are used to solve the whole domain down to the solid wall. For the HRN turbulence models, wall
functions are used to bridge the near wall region. When two structures are far away, the computation for apoint located in the fluid can be handled normally. However, when these two structures approaches andbecome very close to each other, their boundary layers will overlap. After the two structures impact eachother, they will become separated and a reversed flow will happen. When two structures approach with ahigh relative speed (High Re), the boundary layer near the surface of the two structures is turbulence.
Similarly with the Low Re case, fluid “jets” in both orthogonal directions happens and singular point
appears during approach with a fast relative velocity. When two structures approach and become very
close to each other, their boundary layers will overlap. After two structures impact each other, they will beseparated immediately and a reversed jet flow will happen. If the separation speed is high enough,cavitations may occur in their wake regions because of negative pressure. When free surface exist, thepressure on the surface will be constant. As two structures approach with a high relative speed, the fluid
jet will flow in a preferred direction, i.e., the free surface direction, and a dome will occur in the freesurface because of the jet. When the two structures are very close to the free surface, the turbulent
boundary layer maybe interacted with the free surface. As two structures separate in a high speed, the freesurface will be pulled downward because of negative pressure. When cavitation occurs, the free surface
will be interacted with the bubbles floating up. The free surface will be changed. When implementing thecomputation, the following questions need to be resolved:•

Which normal distance is valid when using damping functions?

•

When the solid is very close to the wall, i.e., when two boundary layers overlap, how will theboundary effects be determined (calculate)?

•

After the contact elements are generated in the numerical code, can the boundary layer beneglected?

•

How will the cavity interacting with free surface be modeled?

These questions will be addressed in future follow up papers.
Reference:
Yim, C.S. (2005): Tsunami and Storm Surge Hydrodynamic Loads on Coastal Bridges. The 21st US-Japan
Bridge Engineering Workshop, Tsukuba, Japan, Oct. 4-6, 2005, Session 3, Coastal Bridges, pp.1-14.

44

Numer ical Model for Estimation of Damages due to Tsunami
MURATA, Susumu
Coastal Development Institute of Technology, Tokyo, Japan, s_murata@cdit.or.jp

KOYANO, Yoshiji
Coastal Development Institute of Technology, Tokyo, Japan, koyano@cdit.or.jp

TAMEHIRO, Tetsuya
former Coastal Development Institute of Technology, Tokyo, Japan

1.

Introduction

Tsunami damage is usually estimated by computing the inundated area. However, the out-flow of vehicles,
drifting of ships, drifting objects colliding with buildings and the damage of buildings by the tsunami’s
flow pressure, all cause serious damage to the society. Therefore, to make an accurate plan for damage
reduction it is useful to utilize a numerical model which can estimate various types of damage due totsunami. This report shows tsunami simulation models which also consider energy in the water level, its
velocity and results of simulation computed for Sendai port and Kesennuma Bay.
2.

Study flow and Digitizing of Topogr aphy
Digitizing of Topography (minumum grid size: 2m)

Establishments of sub-models for 'Run-up', 'Outflow andDrift', 'Sp illed Oil Dispersion', and 'Building Damage'

Implementing simulations at model ports(Sendai and Kesennuma)

Figure 1 shows the flow of this study. For the
calculation of tsunami propagation, special grid size is
set into 6 zones (1,350m to 2m), with grid size
decreasing as the tsunami approaches from the origin
to the objective port. The ‘Run-up’ sub-model mainly
covers the land with 2m grid, in order to precisely
consider the topography and scale of building.

Tsunami disaster damage estimation based on
numerical simulation results

Figure 1： Study flow
3. Numer ical Simulation Model
The model is composed of 4 sub-models;
1) ‘Run-up’ sub-modelThis sub-model is based on the two-dimensional non-linear long wave theory and the Leap-Frog method
is used for the time differential scheme.
2) ‘Outflow and Drift’ sub-modelThis sub-model is based on an advection-diffusion model considering drag force and the additional massof drifting objects, i.e. automobiles, timber, containers, vessels and aqua cultural floats, following Goto
(1983).
3) ‘Spilled Oil Dispersion’ sub-model
In this simulation, it is assumed that storage tanks are damaged by the quake causing oil spill in thespilled-oil protection compound. And then the spilled oil is dispersed by the tsunami which overflows the45barrier into the compound. The oil diffusion is simulated by the same method as that of Goto(1985).
4) ‘Building Damage’ sub-model
Damage of building is estimated by comparing building strength with drag force based with estimatedinundation based on the research by Iizuka and Matsutomi (2000).
4. Simulation Results
Major results of simulations are as follows;
1) ‘Outflow and Drift’ simulation results
Before
津波発生前

５時間後
After
5 hours

In Kesennuma Bay many of vehicles, vessels andaquacultural floats flow out in 5 hours after theearthquake as shown in Figure 2, while at Sendai
port no container or timber out flow from the landside, except for some vehicles, due to the limited
depth of inundation.

Figure 2: Drift of vehicles in Kesennuma Bay2) ‘Building Damage’ simulation results
Wooden building (no damage)：木造（破壊しない）
Reinforced concrete building (no damage)：鉄筋コンクリート造（破壊しない）：木造（中破）Wooden building (part damaged)：木造（大破）Woodenbuilding(seriously
damaged)：鉄筋コンクリート（大破）
Reinforced concrete building (seriously
damaged)At Sendai port, buildings within the inundated area are all RC
structures and the depth of water is limited. No destruction ofbuildings occurred.
In Kesennuma Bay area many buildings are destroyed as shownin Figure 3 because there are many wooden buildings and water
depth of inundation is 3 meters.
3) ‘Oil Dispersion’ simulation results
At Sendai port, the incoming tsunami did not overflow the oil
protection compound, thus no oil dispersed into the sea.
However, at Kesennuma port, the tsunami overtopped the oil
protection compound and the spilt oil dispersed outside thecompound barrier.

Figure 3: Building destruction simulation at Kesennuma port
5. Conclusion
In this study, run-up height on land, water depth and velocities are used as parameters to calculate the tsunami’s
energy. The model revealed not only of the inundation, but also damage to buildings as well as outflow and drift ofmaterials on land in addition to vessels in the port. Therefore, this simulation model is useful for predicting probabledamages of tsunamis and for formulating effective countermeasures.
6. References(1) Goto, T. (1985): A simulation model of oil spread due to tsunamis, Proceedings of JSCE, No. 357/II-3,
pp. 217-223(2) Goto, T. (1983): A simulation model of outflow of lumber due to tsunamis, Journal of Coastal
Engineering, Vol. 30, pp. 594-597(3) Iizuka, H. and H.Matsutomi, (2000): Estimation of damage by tsunami inundation flow, Journal of
Coastal Engineering, Vol. 47, pp. 381-385

46

DETERMINATION OF PERIODS OF FREE OSCILLATIONS FOR
THE IRREGULAR SHAPED BASINS BY NUMERICALTECHNIQUE
Ahmet C Yalciner
Middle East Technical University, Department of Civil Engineering, Ocean Engineering
Research Center, 06531 Ankara, Turkey
Efim N Pelinovsky
Laboratory of Hydrophysics and Nonlinear Acoustics, Institute of Applied Physics,
Nizhny Novgorod, Russia,
1. Intr oduction
The subject of oscillation inside harbors, bays, or any other semi-enclosed or closed basins is a problem
that can have direct influence on the management of harbors, shipping and coastal utilization in the caseof tsunami events. The waves entering the basins cause water surface fluctuations dependent on thecharacteristics of the incoming waves and the boundary conditions of the basins. Short period waves
entering continuously to the small basins such as harbors in general may generate abnormal wave
conditions and cause unexpected damages. Response of the basin, together with the wave characteristics
may result in amplification of these waves and in higher surface fluctuations. Response of the basin
depends on reflection and energy dissipation characteristics of the boundaries and the geometricproperties of the basin. The wave periods that result in higher water surface fluctuations are the periodsof oscillation of that basin. Periods of free oscillation depend on the dimensions of the basin; larger
basins have higher periods of oscillation.
Resonance, when occurs, may cause difficulties in harbor operations, result in crashing of small crafts inmarinas, and give significant damage to the coastal structures in the basin. If the basin is larger such asbays or enclosed seas, then the periods of free oscillations will be larger and may result with higher
amplitudes. The sudden energy transfer to the sea related to the fault break or submarine and/or
subaerial landslides may generate tsunamis and propagate towards shore and cause disturbances inside
the semi-enclosed basins for a long time. The amplitudes of the disturbances are also dependent on theamplitude of the waves and the characteristics (shape, depth and boundary conditions) of the basins.
Long waves, especially tsunamis, may have highly destructive effects on coastal structure and mooringcrafts. Their effects become much higher and may continue longer duration when the wave period
coincides with the period of free oscillation of the basin, harbor or bay.
Scope of this study is to investigate the behavior of the basins under the disturbances caused by longwaves, and to develop a short cut numerical method for determining the periods of free oscillations of
the irregular shaped enclosed or semi-enclosed large basins and/or bays.
The numerical method used in this study has been given in Yalçıner et. al. (1993, 1995). In the method
application, a single wave is inputted to the basin as an initial impulse, and the propagation of this wave
in the basin is computed by using the numerical method solving the nonlinear form of wave equations.
The time histories of water surface fluctuations at different locations due to propagation of the waves inrelation to the initial impulse are stored and analyzed by the Fourier Transform Technique and energy
spectrum curves for each location are obtained. The periods of free oscillations are determined from thepeaks of the spectrum curves. The method is tested by using the regular geometrical shaped basins; i)rectangular shaped basin with two different horizontal and inclined sea bottom profiles ii) and acylindrical shaped flat bottom basin with different water depths. The computed periods of freeoscillations are compared with the theoretical values. The effect of the bathymetry and the characteristicsof the numerical method on the computed frequencies of the modes of free oscillations are also discussed.

47

The method is also applied to the problem of determination of free oscillations for the earthquake
generated waves in the irregular shaped basins of uneven bathymetry such as the sea of Marmara andIzmit bay. The results obtained for these basins are presented and discussed.
2. Method
The method used in this study was tested by Çakıroğlu (1997), for regular shaped basins whose
resonance periods are known analytically. The procedure to determine the periods of free oscillation ofan arbitrary basin is straight forward by this method. Long wave equations for shallow water describe
the motion of long waves inside the basin. These equations can be solved using the appropriate boundary
conditions with the existence of a single wave as the external force. For duration of time, the solution
can be applied to determine the water surface elevation fluctuations for selected locations of the basin.
Fourier Transformation Technique is used to obtain the frequency spectrum curve for each location of
the basin. Peak values of the frequency spectrum curve will show the periods of free oscillation of theselected location. The periods of free oscillations of the whole basin is obtained by examining andcomparing the occurrences of each period of oscillation.
3. Application to the sea of Mar mar a
Several runs are carried out for the test, by using two different initial impulses. In the first application,
the impulse having the crest along East-West direction, which makes the wave propagation along NorthSouth direction. In the second application, the impulse having the crest along North-South direction,
which makes the wave propagation along East-West direction.
The periods where the spectrum curve shows peaks are listed for each location for each test as theperiods of free oscillations of that location. The most common periods are selected to represent theperiods of free oscillations. It was found that 218.min, 72. min., 36min., 31min, 26min., 15min., 12min.,
105min., 9min. are some of the periods of free oscillations of the sea of Marmara. The accuracy of theresults of any numerical method is dependent on the grid spacing, size of time step, and the duration of
the simulation. In this method for more accurate results, it is recommended that the grid spacing andtime step in the simulation must be sufficiently small, and the simulation duration must be sufficiently
long.
Acknowledgements
This research is supported by INTAS (03-4286) and RFBR (05-05-64265) for Russian author. METU
Basic Research Fund is acknowledged by its support to Turkish author for developing and application of
the model with the research number AFP-2001-03-03-06. The depth data is developed by TUBITAKYDABCAG-60 Basic Research Grant in Turkey. The sincere gratitudes are also extended to both Prof.
Fumihiko Imamura and Prof. Costas E. Synolakis for their long term endless collaboration with theauthors in modeling of tsunamis. The long wave propagation model TUNAMI-N2 used in this paper is a
registered copyright of Professors Imamura, Yalciner and Synolakis.
Refer ences
Bruun, P. (1981), ‘Port Engineering’ Gulf Publishing Company, Book Division, Houston, London, Paris,
Tokyo, pp. 94-108.
Çakiroğlu,Y. (1997),’Numerical Method For Determination Of The Periods Of Free Oscillations Of
Basins For Earthquake Induced Waves‘ Coastal and Harbor Eng., METU, Ankara, Thesis.
Imamura, F. and Goto, C. (1988), ‘Truncation error in Numerical Tsunami Simulation by the Finite
Difference Method’ Coastal Engineering in Japan, Vol. 31, No: 2.
Imamura, F. and Shuto, N. (1989), ‘Numerical Simulation of the 1960 Chilean Tsunami’ Proceedings of
the Japan-China (Taipei) Joint Seminar on Natural Hazard Mitigation, Kyoto, Japan.
Karatoprak C., (2000), “Long Wave Transformation and Resonance Study For The Closed Basins”, M
Sc Thesis, Middle East Technical University, Civil Engineering Department, Ocean Engineering
Research Center, June 2000 (76 pages)
Shuto, N., Goto, C. and Imamura, F. (1990), ‘Numerical Simulation as a Means of Warning for NearField Tsunami’, Coastal Engineering in Japan, Vol. 33, No. 2.
Yalciner A. C. Alpar B., Altinok Y., Ozbay I., Imamura F., (2002), "Tsunamis in the Sea of Marmara:
Historical Documents for the Past, Models for Future" Marine Geology, 2002, 190, pp:445-463

48

Yalciner A. C., and Pelinovsky E., (2005), A Short Cut Numerical Method for Determination of
Resonance Periods of Free Oscillations in Irregular Shaped Basins, Accepted for publication in Ocean
Engineering

49

DEVELOPMENT OF TSUNAMI DAMAGE ESTIMATION TOOL

Takashi Tomita
Port and Airport Research Institute, Yokosuka, Kanagawa, Japan, tomita@pari.go.jp

Kazuhiko Honda
Port and Airport Research Institute, Yokosuka, Kanagawa, Japan, honda@pari.go.jp

Taro Arikawa
Port and Airport Research Institute, Yokosuka, Kanagawa, Japan, honda@pari.go.jp

1. Introduction
As many historical tsunamis did so, the 2004 Indian Ocean Tsunami taught us that tsunamis haddevastating forces and caused various damages such as destruction of structures, beach erosion, etc which
resulted in many human losses. The most important and essential measure to minimize human loss isevacuation. However, many people do not evacuate immediately even when they feel earthquake motion
in a tsunami prone area, because they wait information of the earthquake and its induced tsunami todecide whether they should evacuate or not. Moreover, even if they catch a tsunami warning by a
responsible organization, some people do not evacuate, because they misunderstand characteristics oftsunami and vulnerability against tsunamis in their living-areas. To encourage evacuation, the people wholive in tsunami prone areas should understand the disasters caused by the tsunami expected to attack
there. Actually many people evacuated in Sumatra at the tsunami event on March 28, 2005, because they
had the experience of tsunami disaster caused by the Indian Ocean Tsunami on December 26, 2004.
If we can estimate the expected tsunami damages actually, we can also construct holistic defense
system against the tsunamis, which combine structural measures to reduce the tsunami and non-structural
measures to support evacuation. At present, numerical simulations are the most useful tool to predict andunderstand the tsunami attacking coasts, and actually numerical models based on nonlinear/linear shallow
water theory have been used to estimate tsunami height, tsunami arrival time and inundation areas.
Moreover, Fujima et al. (2002) and Yoneyama et al. (2002) showed that three-dimensional andnon-hydrostatic models are effective to estimate the tsunamis interacting with structures and local
topography, respectively, through the comparison with experimental results. The authors have also
developed another tsunami numerical model named STOC (Storm surge and Tsunami simulator in
Oceans and Coastal areas) which is an integrated models based on the combination of three models. Suchmodels can estimate the tsunami running up lands and resultant various damages as well as tsunamis
propagating in the oceans, because they can calculate the complicated tsunami flow interacting withstructures and tsunami forces acting on the structures.

50

2. Numer ical Models to Estimate Tsunami Damages
The numerical model of STOC is composed of three different sub-models: STOC-ML, STOC-IC andSTOC-VF, in order to calculate the tsunamis interacting with structures as well as propagating in theoceans.
STOC-IC is a three-dimensional and non-hydrostatic model, which is developed to estimate thetsunami affected by structures in a wide area whose spatial scale is more than dozen square kilometer likea coastal city and town. It connects to STOC-ML through overlapping zones in which the physicalquantities such as the water surface displacement, velocities, pressure, etc. in each computational area of
STOC-IC and STOC-ML are adjusted using the interpolation technique. The governing equations of
STOC-IC are Reynolds-Averaged Navier-Stokes equations and continuity equation for incompressible
fluid in three dimensions, including eddy viscosity models. A technique to reduce computational efforts is
to use the vertically-integrated continuity equation to detect the free water surface duce computational
effort. This brings wide computational area to which the three-dimensional model is applied.
STOC-ML is a multi-level model in which water bodies are divided vertically into some horizontal
layers. The governing equations are almost same equations as STOC-IC, although the assumption ofhydrostatic pressure is applied in each layer. No calculation of Poisson equation of water pressure results
in reduction of computational effort and then STOC-ML is applied to wide areas such as the oceans.
STOC-VF is also fully three-dimensional and non-hydrostatic model. The difference from STOC-IC
is the detection technique of the free water surface. This model applies the Volume Of Fluid (VOF)
method to do that. Since the VOF method can calculate the waves breaking and overtopping structures,
STOC-VF provides the estimation of destruction due to the tsunami striking impulsively.
3. Application to the 2004 Indian Ocean Tsunami
Combination of STOC-IC and STOC-ML is applied to the Indian Ocean Tsunami in Galle, Sri Lanka,
using a nested grid system based on bathymetry data from GEBCO 1-minute global bathymetric grid, andnautical charts, and topography and structure data. Comparing the result by the traditional tsunami
simulation which considers roughness instead of buildings on land, the computational result taking into
consideration the existence of buildings and using STOC-IC provides less difference on the maximum
inundation depth in the hinterland of no coastal facilities to protect waves and tsunamis. However, there ismuch difference in the inundation process of the tsunami running up. Existence of buildings has the effectof delaying the tsunami propagation behind them, because the tsunami has to run around them and go toanother path in some areas.
References
Fujima, K., K. Masamura and C. Goto (2002): Development of the 2d/3d hybrid model for tsunami
numerical simulation, Coastal Engineering Journal, 44(4), 373-397.
Tomita, T. and K. Honda (2006): Application of three-dimensional tsunami simulator to estimation oftsunami behavior around structures, Proc. Int. Conf. Coastal Eng. (in press).
Yoneyama, N., M. Matsuyama and H. Tanaka (2002): Numerical analysis for locally high runup of 1993
Hokkaido Nansei-Oki Seismic Tsunami, Journal of JSCE, 705, 139-150 (in Japanese).

51

52

TSUNAMI HAZARD MAP SEMINAR

HAZARD MAP TO BUILD THE UNDERSTANDINGS AND
AWARENESS OF TSUNAMI DISASTERS

Takashi Tomita
Port and Airport Research Institute, Yokosuka, Kanagawa, Japan, tomita@pari.go.jp
1. Introduction
Activities for tsunami risk reduction would start form the understandings and awareness of tsunami disasters. If thedisaster can be figured out, some measures can be required: measures to protect social and individual
properties, measures to save human lives, and etc. In fact, Japan has constructed many kinds of and a lot of
measures to prevent disasters in coastal areas which suffered tsunamis damage actually in history. The effect ofcountermeasures makes the number of devastating disasters and the degree of damage be reduced recently. However, the1993 Hokkaido Nansei-Oki Earthquake Tsunami caused severe disaster again in the Okushiri island which suffered thedisaster by the 1983 Sea of Japan Earthquake Tsunami. The 1993 tsunami of 10 meters or more in high overtopped theseawall that was constructed after the 1983 tsunami. The height of the 1983 tsunami was 4 meters smaller than the 1993
tsunami. As indicated by this repeated disaster, natural forces such as a tsunami can sometime exceed theestimated level based on historical damage. For disaster management to minimize the tsunami disaster,decision-makers, disaster management officials, and inhabitants should understand the feature of tsunami
and its induced damage, and prepare the next disaster.
2. Tsunami hazar d map
The tsunami hazard map provides a graphical indication of the areas predicted to be influenced bypossible tsunamis. The most fundamental tsunami hazard map would indicate the inundation areas by thehistorical tsunamis. In many tsunami-prone areas, tsunami inundation maps have been made as a tsunami
hazard map. They are much useful to build the understandings and awareness of the vulnerable areas tothe possible tsunamis. The inundation map together with the indication of historical disasters would be
more effective in understanding the possible damage.
The accuracy of computed inundation area depends on the resolution of topography and bathymetry as
well as the fault model of the earthquake which defines the initial condition of the tsunami form.
Especially, fine topography data yields better estimation of tsunami inundation. Development of leaser
scanning technology provides the detailed survey of topography.
It has pointed out that there is difficulty to understand the indication of the inundation map. In the map,the areas without the inundation are also shown in the contrast of the inundated areas. Are thenot-inundated areas always safe to all tsunamis? For example, in the Ofunato bay of Japan, the inner bay
coast had less damage by historical tsunamis generating near the coast while it suffered hardly damage by the Chilean
Tsunami which propagated from far filed. This difference results from the resonance of tsunami by the bay. The
inundation map gives just one or some numerical simulation results of the possible tsunamis and/or thehistorical disaster results. The next tsunami could inundate the areas beyond the border of the inundationin the hazard map. Therefore, we should consider how to draw the results in the hazard and inhabitants

53also learn the meanings of the indication in the hazard map. To overcome the problem, the damage by thetsunami striking actually should be estimated in real-time.
3. Advanced hazar d map
The 2004 Indian Ocean Tsunami showed us tsunami destruction as well as inundation. It also produced
many kinds of drifting objects including debris which caused damage additionally. Estimation of suchdamage brings an advanced hazard map which provides more practical disaster management. Recently,
three-dimensional and non-hydrostatic numerical models began to be applied to the estimation of tsunami.
Estimation of the complicated tsunami features interacting with structures starts with such a numericalmodel.
4. Tsunami disaster management using the hazar d map
Tsunami disaster management should start with the hazard map. Part of the tsunami disaster can beprevented by existing structures, sand dunes and so on, and other part would be reduced by new structures
if their construction is possible. Such things are discussed on the hazard map. Regardless of whether the
structures exist or not, the evacuation is a priority measure to save human life. Addition of evacuationroutes and places into the hazard map provides an evacuation plan map resulting in effective evacuationfrom the tsunami. The indication of the location of the persons who require any supports for evacuation
also make the preparedness of community support system. Effective information and data to reduce thetsunami risk into the hazard map would depend on the characteristics of the area and country: religion,
culture, poverty, and etc.

54

UTILIZATION AND PROMOTION OF TSUNAMI HAZARD MAP
Kentaro KUMAGAI
National Institute for Land and Infrastructure Management (NILIM), Ministry of Land, Infrastructure and Transport

3-1-1 Nagase, Yokosuka, Kanagawa, Japan, kumagai-k27n@ysk.nilim.go.jp

1. Introduction
It is important to estimate the tsunami inundation height and to draw the tsunami hazard map, but also
is important to utilize the map in order to imagine the practical situation of the tsunami and stimulate
inhabitants into evacuation. It is not completed only printing the maps or distribution of the maps to the
inhabitants. But the Inhabitants have to understand the meanings of the symbols, lines, hatching colors
and figures printed in the map and to know what to do before tsunami arrival at the shore. Local
administrative bodies which are responsible for tsunami damage mitigation therefore have to make planfor utilization and promotion of the Tsunami Hazard Map.
2. Examples of Utilization and Promotion of the Tsunami Hazar d Map
The Tokai, Tonankai and Nankai areas are locatedon the coastline of Japan faces the Pacific Ocean.

N

Ulan Bator

0100

200 kmFigure 1 shows their locations. They have high risk oftsunami due to the magnitude eight class earthquakes
around the Nankai and Suruga troughs. It is estimatedBeijing
Tokyo

LegendJapan

Vientiane
Hanoi

Troughs

Close-up area

Bangkok

Boundarys ofPrefectures

ManilaPhnom Penhby the government council that the earthquake can betriggered off by anytime in the Tokai area, and theearthquake will generate in the next 60 years in the
Tonankai and Nankai areas. Shima City is an
attractive resort for its beautiful scenery of seashore
and marine sports points in the middle of Mie
Prefecture in the Tonankai area. A fishery is also themain industry of the city. Kochi City is the capital of
the prefectural government of Kochi Prefecture.

SurugaTroughMie Pref.
Shima City

Tonankai
Area

Kochi Pref.

Tokai Area

Kochi City

Nankai Area
i
nka
Na

ugh
Tro

Pacific Ocean

Copyright: National Institute for Land andInfrastructure Management (NILIM), Japan

Figure 1: Pacific Ocean and Coastal areas of Japan

These cities suffered the tsunami damages for many times in the past and are taking the measures against
the tsunami. Effective utilization of the Tsunami Hazard Map is one of the main measures in these cities.
The measures below are related to the utilization and promotion of the Tsunami Hazard Map:
- Regulation established by the local gover nment
Utilizing a Tsunami Hazard Map, one can easily judge if his or her home would be suffered fromtsunami inundation or not. But it is difficult to make the inhabitants act and evacuate at their own
initiatives. A regulation is enacted by Mie Prefecture in 2006. It provides personal commitments for
citizens and private companies before, in and after the earthquake. All inhabitants and visitors mustevacuate oneself to the safe area from inundation or to shelters in no time of delay if earthquake occurs,

55

tsunami-forecast is announced, or tsunami arrival is estimated. The significant point of this regulation is
the request for the immediate evacuation after the earthquake with no waiting for any kind of advisories,
instructions or orders for evacuation by the municipal. Self-decision-making for evacuation is required forevery inhabitant. Traffics of four-wheel-automobiles are also restricted in the city area. Personal traffic by
car for evacuation will be forbidden in the city areas of Mie Prefecture other than special occasions.
- Or ienteering from one' s home to the tsunami shelter and Dr awing the additional close-up map
The inhabitants are recommended to participate in an orienteering game, a walk event from one's
home or place of work to the nearest tsunami shelter, held in a local community block. It is planed andorganized by the municipal and representatives of
inhabitants from the community. Figure 2 shows theorienteering in Mie Prefecture. The main objective of theorienteering is to learn the routes to the nearest shelter.
But it is also important to find risks that will make theevacuation route impassively. Numbers of problems on
evacuation will be found inevitably from the viewpoint of
inhabitants, such as collapse of houses, fire, landslide,wreck of structurally-weak walls, darkness in the night,

Figure 2: Orienteering *Mie Pref.

lack of the sense of a direction for the strangers, andothers. These practical knowledge and critical information
have to be reflected in the Tsunami Hazard Map.
Inhabitants write the special signs for them in the map. A
Close-up Map can be made additionally if it is necessary.
The Close-up Map is useful because it can expresses
details including shapes of houses and open spaces, thelocations of structurally-weak walls, sites for fire hydrants
and chemical fire extinguishers and others. Figure 3 is a

Figure 3: Close-up map*Mie Pref.

Close-up map draw by inhabitants in Mie
Prefecture. There are 367 local communities along

Conclusion of agreements (PG & TC*)

the coastline of the Mie Prefecture and 197
communities of them already finished to develop

Request for provision of tsunami
evacuation shelter for inhabitants(PG to TC)

their plan for tsunami evacuation by March 2006.

List of buildings (TC to PG)- Agreement for cooper ation between pr ivate

Request for selection (PG to LA*)

company and local gover nment

Figure 4:
Flow diagram ofutilization existingbuildings as
tsunami evacuation
shelters

Building selection (LA)

Figure 4 is a flow diagram regarding theConclusion of agreements (LA & TC)

agreement for cooperation between the local
Add external stairway
to the rooftop floor ?

telecom company and Mie Prefecture, concerning

No

Yes

the utilization existing buildings as a tsunami

Request for 50% subsidy from PG(LA to PG)

evacuation shelters. This agreement was concluded

Construction the stairway (LA)between Mie Prefecture and the telecom company

Promotion and Evacuation exercise(LA & Inhabitants)

in 2004. Prefectural government, Mie Prefecture,

56*PG: Prefectural Govornment
TC: Telecom Company
LA: Local Authority
Data source:
Department of Disaster
Prevention and Crisis
Management, Mie
Prefecturerequests the telecom company to make a list of buildings
which could be utilize as tsunami evacuation shelters.
With the list revealed by the telecom company, the local
authority selects a building. And the agreement isconcluded between the local authority and the electriccompany for utilizing the selected building as a tsunami
evacuation shelter. If necessary, an external stairway isconstructed by the local authority. Figure 5 is an external
stairway,

newly constructed and attached telecom

Figure 5: External stairway*Mie Pref.

Figure 6: Village festival*A. Hirota

company building which was declared as a tsunami
evacuation shelter by local authority of Mie Pref. in 2004.
Cabinet Office of Japan Government edited a
guideline for tsunami evacuation shelters in 2005. The
guideline stated the requirements for the tsunami
evacuation building and its location, method for
estimation of the number of evacuee and others.
- Annual village festival to strengthen up the social
power of the local community
In Kochi City, annual one-day village festival is holdin order to strengthen up the social power of the local community. It is planed and organized by themunicipal and representatives of inhabitants from the community. It is unique because of the joint style ofa festival and an event for disaster prevention. Figure 6 is the people participated in the festival in 2006.
3. Conclusions
In this paper, practical methods of utilization and promotion of the Tsunami Hazard Map are
introduced. But an effective method for utilization and promotion is not uniform because ofcharacteristics of the local communities. Local government should take the most proper measuresaccording to their surroundings. And, in any case, cooperation between the local authority and inhabitants
is essential for the planning of safety evacuation and tsunami damage mitigation.
Acknowledgments
The author wish to express his appreciation for the cooperation received from all concerned in the courseof this research, beginning with the Department of Disaster Prevention and Crisis Management of Mie
Prefecture, the Local Disaster Prevention Office of Shima City, and the Division of Disaster Prevention
Measures of Kochi City. This research is the joint research between National Institute for Land andInfrastructure Management (NILIM) and Independent Administrative Institution of Japan Railway
Construction, Transport and Technology Agency (JRTT).
References
Cabinet Office of Japan Government et al. (2005): A Guideline concerning tsunami evacuation buildings
and other structures, pp.6-29.
Cabinet Office of Japan Government et al. (2004): Manual for Tsunami and Storm Surge Hazard Maps
Mie Prefecture (2004): Mie Prefectural Regulation Concerning the Promotion of Countermeasures toEarthquake, Section 28 and 34.

57

HAZARD MAPPING – A SRI LANKAN EXPERIANCE

Nimal Wijayaratna
Faculty of Engineering, University of Ruhuna, Galle, Sri Lanka, nimal@cee.ruh.ac.lk

1. Introduction
There are no clear guidelines or standards for the preparation of tsunami hazard maps in Sri Lanka.
Confusion is there about the exact procedure that should be followed to prepare a hazard map which has
all necessary information to recognize the degree of risk, means of escaping from the danger and how the
information should be presented so that it is easily understandable to the end users. Guidelines used inother countries are very useful, however they should be adjusted to suite the local conditions. Preparationof a hazard map for the city of Galle, Sri Lanka using the guidelines adopted in Japan is discussed in thepaper highlighting the necessity of a set of local guidelines.
2. Manual for Tsunami and Stor m Sur ge Hazar d Maps
Manual for Tsunami and Storm Surge Hazard Maps, Coastal Development Institute of Technology, Japanwas used as a guideline to prepare the tsunami hazard map for Galle city. The hazard map discussed inthis paper was prepared for safe evacuation of people and some special features of tsunami hazard maps
for administrative purposes suggested by the manual were not used. Therefore an evacuation plan isincluded in the map but it lacks information such as the number of evacuees in evacuation centers,
conditions of evacuation centers etc. which are of administrative importance.
3. Hazar d Map for Galle City
According to the manual, inundation prone areas should be set based on the most critical potential
tsunami event. However there had been only one recorded tsunami event in Sri Lanka and simulating
hypothetical tsunami events is also difficult. Therefore the inundation area during the 2004 Indian Ocean
tsunami was used as the inundation prone area during a future tsunami. A buffer zone was introduced tocover any additional inundation during a more critical tsunami event. Facility risk level evaluation was
not done in preparing the hazard map even though the manual recommends that. Evacuation information
was collected from the residents in the inundation area. No formal gatherings were organized but anevenly distributed sample of households was interviewed to collect information. According to the manual,
there should be several meetings with all stakeholders to verify and correct the information in the map.
However this was limited to collecting the feedbacks from a few selected stakeholders due to thelimitation of resources.
4. Conclusions
It is not practicable to exactly follow the guidelines adopted in other countries due to various differences
and limitations. Therefore a set of local guidelines is necessary for the preparation of hazard maps.

58