1.2011Great East Japan Earthquake and Tsunami Disaster. 2.Mechanism of Tsunami and Tsunami Disaster Mitigation

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1 Tokyo Institute of Technology Jan.10 and 24,2014 Earthquake and Tsunami Disaster Reduction Great East Japan Earthquake and Tsunami Disaster 2.Mechanism of Tsunami and Tsunami Disaster Mitigation Shigeo TAKAHASHI Port and Airport Research Institute, Japan Visiting Professor, Tokyo Institute of Technology

2 Tokyo Institute of Technology FS2011 Feb.2013 Earthquake and Tsunami Disaster Reduction Contents 2.Mechanism of Tsunami and Tsunami Disaster Mitigation 2.1.Mechanism of Tsunami 2.2. Tsunami Damages 2.3.Tsunami Disaster Mitigation

3 2.1.Mechanism of Tsunami Run-up As an engineer it is very important to understand the basics of tsunami mechanism in this chapter.

4 Storm Waves and Their Overtopping

5 Tsunami Wave and Overtopping Tsunami is long and therefore, powerful

6 Tsunami is a very long wave and therefore, very powerful Tsunami has many characteristics as a wave. Tsunami has many characteristics as a flooding current

7 Generation of Tsunami A simplified Model of sea bottom displacement and Initial Tsunami Vertical displacement of Seabottom =Initial Tsunami Profile

8 Propagation of Tsunami Propagation toward shore side and ocean side How high is the tsunami height moving toward the shore?

9 Propagation of Tsunami to Shore Speed becomes slow. Wave length is smaller and height is larger

10 Causes of Deformation of Sea bottom to generate Activity (Earthquake) Movement of Fault in seabottom Subduction Zone Eruption of Volcano

11 Epicenters of Large Earthquakes Earth-Plates Boundaries and Subduction Zones North American Pl. Eurasia Pl. Philippine Pl. African Pl. Pacific Pl. Indo-Australia Pl. South American Pl. Antarctic Pl.

12 Earthquake and Tsunami Generation(1/2) Movement of Techtonic Plates at Subduction zone Continental Plate Ocean Plate (Subducting Plate) Deformation of the Continental Plate is increased by the Subducting Plate. 12

13 Earthquake and Tsunami Generation(2/2) tsunami tsunami tsunami Rupture/ Earthquake Ocean Plate The deformation is released suddenly by rupture which causes an earthquake. 13 The sea bottom deformation causes the tsunami. The tsunami profile is equal to the sea bottom deformation

14 Sea bottom topography and Vertical displacement of sea bottom Displacement of Sea bottom(m)

15 A simplified Model of Initial Tsunami Near the subduction zone the water depth is 1 to 5km and the height is only less than 10m. Also the wave length is 100 to 200 km for example. Vertically and horizontally distorted Picture

16 Numerical Simulation of Generation and Propagation of Tsunami Based on Wave Theory

17 Water Waves (Water Surface Wave/Gravity Waves) Wind Wave Tsunami Storm Surge Tide Tsunami = Very Long Wave (period 10mins to 1hr)

18 Development of Water Wave Theory Gravity wave theory ( From 19 th century) Understanding of the characteristics Numerical simulation of Water waves (From 20 th Century) Now we can calculate Tsunami generation, propagation and run-up.

19 Basics of Long Waves from wave theory Velocity of Water Particles U=(η/h) C (Basic characteristics of tsunami) Speed of Tsunami C=(gh)* 0.5 Continuity of Wave Power η 2 C=η o2 C o Height of Tsunami η=η o (C o /C)* 0.5 =η o (h o /h)* 0.25

20 Speed of Tsunami C=(ｇh)*0.5

21 Height of Tsunami η=η (Co/C)* 0.5 =η o (h o /h)* 0.25

22 Velocity U and Displacement X of Water Particles; U=(H/2h)*C Breaking Wave U=10m/s x=3000m U=2.7m/s x=770m U=0.025m/s x=7m

23 Increase of tsunami height due to Geographical features of coasts V-shape bay By contraction Cape By Refraction Behind island By Diffraction

24 Four Typical Types of Tsunami Run-up Due to coastal topography tsunami run-up changes significantly

25 Tsunami at Sendai Plain NHK Special The Great Eastern Japan Earthquake by NHK (Japan Broadcasting Corporation) on May 7, 2011.

26 Breaking Wave Type A typical tsunami run-up in a sandy beach and intrusion into a lowlying land

27 Tsunami at Kamaishi

28 Overtopping Type A typical runup type in ports and rivers

29 Four Typical Types of Tsunami Run-up Due to coastal topography tsunami run-up changes significantly

30 Special feature of tsunami front in coasts. Soliton Fission (Split) and Breaking of Tsunami Front The behavior of tsunami front near the coasts is very important especially to understand the mechanism of failures of coastal defenses.

31 Tsunami front with Soliton Fission at a water depth 30m NHK Special The Great Eastern Japan Earthquake by NHK (Japan Broadcasting Corporation) on May 7, 2011.

32 Tsunami at Kuji (Breaking of soliton waves)

33 Tsunami at Kuji (Breaking wave front) NHK Special The Great Eastern Japan Earthquake by NHK (Japan Broadcasting Corporation) on May 7, 2011.

34 Summary of Tsunami Generation, Propagation and Run-up 1.Tsunami is a long and powerful wave. 2.Deformation of sea bottom generates tsunami. 3.Tsunami propagates with the speed of Root gh. The tsunami speed is very large in deep water like airplane. But it becomes slow near coasts like cars. 4.Tsunami increases the height as the water depth decreases. In the coasts it becomes several times. 5.Due to reflection and refraction tsunami attack the coasts many times.

35 Summary of Tsunami Generation and Propagation 6.Due to the coastal geographical features incident tsunami height varies significantly. 7.The run-up of the tsunami into shore and land is very different depending on the topography. 8. Tsunami intrudes into land from rivers and coasts in addition to ports. 9. Tsunami front is very dangerous due to breaking.

36 2.2. Tsunami Recent Tsunami Disasters Results of field Recent Studies on Tsunami Damages Experiments on tsunami Summary of Tsunami Damages

37 Field Surveys of Tsunami We believe that disaster prevention starts from understanding of disaster by people. We have to know what will actually occur by tsunami. We need to prepare for Disaster Scenario to let people know. We can learn from actual disasters. We conducted many field surveys in Japan and in the world.

38 Hambantota in Sri Lanka, Indian Ocean Tsunami 2004 M9.1 Dead/Missing 220,000

39 Pangandaran JAVA July 17, 2006 M7.7 Casualties700 Water Mark m Ground Level m

40 GIZO Solomon Islands April2, 2007 M8.1 Casualties:52

41 Sumatora South-West September 12,2007 M8.4 Tsunami was small. Casualties:20

42 Samoa 9/ M8 140 casualties 42

43 2010 Chilean Earthquake and Tsunami (Feb M8.8, casualties 800)

44 Talchuano, Chilean Earthquake and Tsunami, Feb.27,2010 Photo: The International Federation of Red Cross and Red Crescent Societies Tsunami height 7~8m 680 Containers were drifted toward the town and then 30% of them moved toward the sea. 11

45 Talchuano, Chilean Earthquake and Tsunami, Feb. 27,2010 Photo: The International Federation of Red Cross and Red Crescent Societies 11

46 Dichato, Chilean Earthquake and Tsunami Feb. 27,2010 Photo: The International Federation of Red Cross and Red Crescent Societies 11

47 Dichato Chilean Earthquake and Tsunami Feb. 27, damage in lowlying area near a river Photo: The International Federation of Red Cross and Red Crescent 18 dead among

48 Robinson Crusoe Island: Before and after the Tsunami La plaza y el muelle.

49 Magnitude of Earthquake and Tsunami M7 limited Local Tsunami M8 Large Regional Tsunami M9 Huge Ocean Tsunami

50 Frequency of Tsunami Disasters Tsunami repeats with a frequency of 100 years or more in the same area. In Japan: Major tsunami disasters occur once for ten years. Devastating tsunami disasters occur once for hundred years. In the world: Major tsunami disaster occurs almost for one or two years. Devastating disaster occurs once for ten or twenty years.

51 Summary of Major Tsunami Disasters Tsunami Disasters Place Casualties 2011 Tōhoku Earthquake and Tsunami Japan 20, Indian Ocean Tsunami Indonesia 220, Messina Earthquake (Landslide) Italy 70, Meiji-Sanriku Earthquake Japan 22, Eruption of Krakatoa Indonesia 36, Arica Earthquake Chile 25, Unzen Eruption and Earthquake (Landslide tsunami) Japan 10, Great Yaeyama Tsunami Japan 13, Lisbon Earthquake and Tsunami Portugal 100, Hōei Earthquake and Tsunami Japan 30,000

52 Experimental studies on tsunami damage Prototype Experiments in Large Hydro-Geo Channel to investigate tsunami damages

53 Destruction of a wooden house

54 Destruction of a Wooden House

55 Destruction of Concrete Wall

56 Collision of Container

57 Tsunami Force on Evacuation Building

58 Stability of Human Body against Tsunami

59 Simulation of Tsunami intrusion into a port town

60 Numerical simulation on tsunami inundation using a super computer (Arikawa)

61 Relation between Tsunami Damage and Tsunami Height - Imamura/Iida (modified) Tsunami Height Damage 0.5m No damage 2m Damage in Coasts and ships 4-6m Severe Inundation and casualty 10m- Devastating Damage even in the places far from coast

62 Coastal Defenses Ports and Coasts General 10m tsunami damage 10m Tsunami Causes all the damages due to tsunami. It destroyed everything in the town including coastal defenses. Destruction and washed-away of houses Drift and crash of cars Fires Destruction of tanks and oil spill Destruction of Railways, roads and bridges subsidance of ground Inundation of rice paddles Drifting and collision of ships Destruction and inundation of port faciliteis Drifting and collision of timbers and containers Debris deposit in ports Scouring and deposit in ports Scouring of sandy beaches and destruction of green belts Destruction of acuaculture facilities Scouring and sliding of Breakwaters and quaywalls Destruction of jetties and detached breakwaters Destruction (scouring) of Dykes and Seawalls Destruction of water gates

63 Typical Damages to Tsunami Defenses Difference of Water Level (Sliding of Wall) Rapid Current (Scattering and Scouring) Wave Impact (Seawall Failure Rapid Current (Seawall Scouring and Overturning)

64 Summary of Tsunami Damages 1. Generally, Tsunami attacks the lower areas near coasts. 2. Even by a small tsunami, people might be killed, cars are floated, and wooden houses are damaged. 3. Huge tsunami destroys all the town including coastal defenses.

65 Summary of Tsunami Damages 4. Ships and other floated objects causes the secondary damages. 5. Fire can always occur and cause significant the secondary damages. 6. Receding current is very strong and carries the floated objects into sea. 7. Concrete buildings are relatively strong. 8. Number of Casualties depend on the number of inundated houses. However, it deeply depends on the evacuation rate.

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67 3.Tsunami Disaster Structural countermeasures We need to improve our preparedness by nonstructural and structural countermeasures.

68 Improvement of Preparedness We have to improve our town to be resilient to Tsunami disaster. Reduce the casualties into zero Resilient town = Ensure early recovery = Reduce damage

69 What is the most significant difference between Earthquake and Tsunami Attacks? TIME We can have a time for evacuation against tsunami attack! We can reduce the casualty by tsunami into zero by proper evacuation.

70 Non-structural Countermeasures 1.Effective Warning Hazard Evacuation Facilities(Building,Tower etc) 2.Dissemination of Tsunami Knowledge 3. Land Usage Planning

71 Casualties vs Population in inundated area Huge Tsunami without Early Warning 1896 Meiji Sanriku Tsunami 22000/72500=30% Indian Ocean Tsunami (Banda Ache) 79000/140000=56% Huge Tsunami with Warning 2011 Great East Japan Tsunami 19000/620000=3% Medium Tsunami with Warning 1983 Nihonkai-Chubu Tsunami 104/9900= 1% We can reduce the casualties less than 1%, zero! Evacuation with proper warning is very important!

72 Tsunami Warning System Warning Warning=Large Tsunami(3,4,6,8,10m above) Tsunami (1,2m) Caution=0.5m Local Earthquake Tsunami(1954) New system (1999) JMA Tsunami Database (100,000 Calculated Tsunamis) Within 3 min. Distant Earthquake Tsunami(1960) International Cooperation Tsunami Early Warning System

73 Improvement of Tsunami Warning For 2011 tsunami, the early warning was not so accurate. To issue the warning within 3 minute the predicted tsunami was not large enough More accurate tsunami Prediction Offshore Tsunami Observation Real-time Tsunami Prediction using the observed offshore tsunami data.

74 GPS Buoy (Wave andtsunami Meter) satellite GPS Tsunami Meter Data Tsunami

75 GPS buoys for wave and tsunami observation by MLITT

76 Plan of Underwater Cable Network for Earthquake and Tsunami observation. National Research Institute for Earth science and Disaster Prevention Underwater Seismometer sand Pressure Meters with cable net works

77 Improvement of Evacuation Methods 2011 Great East Japan earthquake and Tsunami Disaster Evacuation places were not so close to people. Many people encountered Tsunami during long evacuation Many people used cars and involved in traffic jams. Tsunami Evacuation = Vertical Evacuation Evacuation Buildings High Lands and Evacuation Towers

78 Improvement of Evacuation Not Horizontal but Vertical Evacuation 5 Minutes Evacuation by Emergency Refuge using High Buildings Modern concrete buildings were inundated but remained.

79 Manual for Tsunami and Storm Surge Hazard Map

80 Tsunami Hazard Map of Suzaki Bay Suzaki City

81 Hazard Map Workshop by Stakeholders

82 Other measures for safe evacuation Seminars and Lectures for disaster education Installation of Evacuation sign boards Improvement of evacuation places Transmission of tsunami experience Preparation of evacuation building Improvement of evacuation routes

83 Meiji-Sanriku Tsunami Disaster Monument

84 A Book to memorize Showa- Nankai Tsunami (1946) at Kainan Town for their descendants

85 Tsunami Books

86 Temporary Evacuation Place i n Tanabe Town Emergency Vertical Evacuation

87 Evacuation Tower (Taiki Town) 5 Minutes Evacuation = Vertical Evacuation

88 Resilient Coastal Towns Disaster reduction (mitigation) to ensure early recovery 沿岸部低地での津波防災まちづくり ( イメージ ) Compact Coastal Towns by House Relocation into high lands and High Buildings near Coasts

89 Laws for Coastal Disaster Prevention Not only earthquake and tsunami we have typhoons and therefore storm surges and waves in the coasts. In 1959 we had ISEWAN Typhoon which killed 5000 people We are preparing for coastal disasters under Seacoast Acts and Disaster Prevention Acts from 1950 s.

90 History of Disaster Prevention Acts In 1961Disaster Countermeasures Basic Act In 1962 Act concerning special financial support to deal with the designated disaster of extreme severity In 1962 Establishment of Central Disaster Management Council In 1963 Formulation of Basic Disaster Management Plan In 1972, Act concerning special financial support for promoting group relocation for disaster mitigation

91 History of Disaster Prevention Acts In 1978, Large Scale Earthquake Countermeasure Special Act ( Basic plan for earthquake disaster of jurisdictions and responsibilities for disaster management system and actions and of emergency

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93 Structural Countermeasures Tsunami Seawalls Tsunami Dike Tsunami Breakwater Tsunami Gate Artificial High Ground

94 Houei Nankai 1707 Ansei Nankai 1854 Showa Nankai 1946 Tsunami Dike by Hamaguchi Hiro Village From HP of Hirokawa-Town

95 Inundation areas due to Ansei Nankai 1854 Showa Nankai 1946 From HP of Hirokawa-Town

96 Taro Town Before 1933Tsunami(Showa Sanriku Tsunami) From HP of Miyako City

97 Taro Town Aftere 1933 Tsunami(Showa Sanriku Tsunami) From HP of Miyako City

98 TARO Town (Miyako City) 1611/1896/1933 Tsunami wall TP10m Total 2433m( )

99 Tsunami Seawall

100 Tsunami Gate

101 Tsunami Gate

102 Aonae Disrict of Okushiri Island Hokkaido Nansei-Oki(M 7.7) 1993

103 Land use planning in Aonae District Tsunami Countermeasures (Aonae District) New Town Park Seawall Reclamation

104 Completed tsunami mitigation works In Aonae Fishery Port Area 6m Seawall 11m seawall Artificial High Ground Fishery Port

105 Tsunami Breakwaters Kuji Kamaishi Ofunat Shimoda Suzaki

106 Kamaishi Bay-mouth Breakwater North 990m South 670m Opening 300m

107 New Tsunami Mobile Gate ( Air Cylinders)

108 New Tsunami Mobile Gate- Flap gate

109 Green-Belt (Coastal Forests)

110 Study on Coastal Forests against Tsunami

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112 Tsunami Risk Assessment Risk=Hazard x Vulnerability Vulnerability = Ground Height Population Economic Activities Preparedness Scenario based risk assessment

113 First, we should write a disaster scenario (what will actually occur) if we have Level 1 tsunami or Level 2 tsunami now. Disaster Scenarios and @Recovery

114 Improvement of preparedness Based on the disaster scenarios we have to improve preparedness using various structural and non-structural counter measures gradually. We always need to know what is the weakest point for tsunami in each town.

115 Concluding Remarks

116 International Workshop on Coastal Disaster Prevention

117 Summary of the 4 th International Workshop on Coastal Disaster Prevention (Direction of tsunami disaster mitigation) 1. The primary objective of disaster management is to save human lives. Additionally, disaster management is critical for mitigating damages to property and society especially from tsunamis and storm surges. Providing the most effective prevention and management demands that governments use the best existing technology and science available. All countries in the Asia-Pacific region are affected by tsunamis and storm surges and they should work together through international cooperation and collaboration to provide the best disaster management and risk mitigation possible with existing technology and science.

118 Summary of the 4 th International Workshop on Coastal Disaster Prevention (Direction of tsunami disaster mitigation) 2. Although basic tools for disaster management are available, it is imperative that we, researchers, scientists and engineers, should develop more advanced technology, not only to reduce the casualties but to maintain the people s activities (to continue their business activities) more effectively and economically. Prediction is key to the effective evacuation and prevention of losses. International cooperation and collabora-tion including sociologists are needed to develop and use the technology effectively.

119 Summary of the 4 th International Workshop on Coastal Disaster Prevention (Direction of tsunami disaster mitigation) 3. To provide the best service to the people of the Asia-Pacific region, we need to enhance disaster preparedness with holistic and resilient disaster mitigation measures. It is no longer acceptable to consider disaster management on a local scale, our vision must extend across the horizon. Solutions to mitigation must be resilient and robust. Participation by people is fundamental to effective disaster preparedness and post-disaster management. Dissemination of the knowledge and cooperation with people at all levels is especially important.

120 Coastal Disaster Mitigation with our wisdom and modern technology The seas are beautiful and rich. Live together with Rich but Violent Seas

121 Thank you for your attention

122 Assignment Please write one page report on tsunami disaster. The title should be Improvement of Tsunami Preparedness in your country. Your report should be submitted before Jan takahashi_s@pari.go.jp