and tsunami disaster mechanism of tsunami and tsunami...

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Tokyo Institute of Technology Jan.10 and 24,2014 Earthquake and Tsunami Disaster Reduction 1.2011Great 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

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Tokyo Institute of Technology

Jan.10 and 24,2014

Earthquake and Tsunami Disaster Reduction

1.2011Great 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

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

2.1.Mechanism of Tsunami

@Tsunami Generation

@Tsunami Propagation

@ Tsunami Run-up

As an engineer it is very important

to understand the basics of tsunami

mechanism in this chapter.

Storm Waves and Their Overtopping

Tsunami Wave and Overtopping

Tsunami is long and therefore, powerful

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

A simplified Model of sea bottom displacement and Initial Tsunami

Vertical displacement of Seabottom =Initial Tsunami Profile

Generation of Tsunami

Propagation toward shore side and ocean side

How high is the tsunami height moving toward the

shore?

Propagation of Tsunami

Propagation of Tsunami to Shore

Speed becomes slow.

Wave length is smaller and height is larger

@Seismic Activity (Earthquake)

Movement of Fault in seabottom

Subduction Zone Earthquake

@ Landslide

@ Eruption of Volcano

Causes of Deformation of Sea bottom

to generate tsunami

Philippine Pl.

Pacific Pl.

Indo-Australia Pl.

North American Pl.

Eurasia Pl.

African Pl.

South American Pl.

Antarctic Pl.

Epicenters of Large Earthquakes Earth-Plates Boundaries and Subduction Zones

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.

13

Earthquake and Tsunami Generation(2/2)

Ocean Plate

tsunami

tsunami tsunami

The deformation is released suddenly by rupture which causes an

earthquake. The sea bottom deformation causes the tsunami.

The tsunami profile is equal to the sea bottom deformation

Rupture/

Earthquake

Displacement of Sea bottom(m)

Sea bottom topography

and Vertical displacement of sea bottom

A simplified Model of

Initial Tsunami

Vertically and horizontally distorted Picture

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.

Numerical Simulation of Generation and

Propagation of Tsunami

Based on Wave Theory

Wind Wave

Tsunami

Storm Surge

Tide

Tsunami = Very Long Wave

(period 10mins to 1hr)

Water Waves

(Water Surface Wave/Gravity Waves)

Gravity wave theory

( From 19th century)

Understanding of the characteristics

Development of Water Wave Theory

Numerical simulation of Water waves

(From 20th Century)

Now we can calculate Tsunami generation,

propagation and run-up.

Speed of Tsunami C=(gh)*0.5

Velocity of Water Particles U=(η/h) ・ C

Basics of Long Waves from wave theory

(Basic characteristics of tsunami)

Continuity of Wave Power

η2C=ηo2Co

Height of Tsunami η=ηo・ (Co/C)*0.5

=ηo (ho/h)*0.25

Speed of Tsunami C=(gh)*0.5

Height of Tsunami η=η・ (Co/C)*0.5

=ηo (ho/h)*0.25

Breaking

Wave

U=10m/s

x=3000m

U=2.7m/s

x=770m

U=0.025m/s

x=7m

Velocity U and Displacement X of

Water Particles; U=(H/2h)*C

Increase of tsunami height due to

Geographical features of coasts

V-shape bay

By contraction

Cape

By Refraction

Behind island

By Diffraction

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

Tsunami at Sendai Plain

NHK Special “The Great Eastern Japan Earthquake”

by NHK (Japan Broadcasting Corporation) on May 7, 2011.

A typical tsunami run-up in a sandy beach and

intrusion into a lowlying land

Breaking Wave Type

Tsunami at Kamaishi

A typical runup type in ports and rivers

Overtopping Type

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

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.

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.

Tsunami at Kuji (Breaking of soliton waves)

Tsunami at Kuji (Breaking wave front)

NHK Special “The Great Eastern Japan Earthquake”

by NHK (Japan Broadcasting Corporation) on May 7, 2011.

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.

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.

2.2. Tsunami Damages

@ Recent Tsunami Disasters

Results of field surveys

@ Recent Studies on Tsunami Damages

Experiments on tsunami damages

@ Summary of Tsunami Damages

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.

Field Surveys of Tsunami

Hambantota in Sri Lanka, Indian Ocean Tsunami

2004 M9.1 Dead/Missing 220,000

Pangandaran

JAVA July 17,

2006 M7.7

Casualties700 Water Mark 3.3-5.4m

Ground Level 2.2-3.1m

GIZO Solomon Islands

April2, 2007 M8.1 Casualties:52

Sumatora South-West

September 12,2007 M8.4

Tsunami was small. Casualties:20

42

Samoa 9/29 2009 M8 140 casualties

2010 Chilean Earthquake and

Tsunami (Feb 27 2010 M8.8, casualties 800)

Talchuano, Chilean Earthquake and Tsunami,

Feb.27,2010

Tsunami height 7~8m 680 Containers were drifted toward the town and then 30% of them moved toward the sea.

Photo: The International Federation of Red Cross and Red Crescent Societies

11

Talchuano, Chilean Earthquake and Tsunami,

Feb. 27,2010

Photo: The International Federation of Red Cross and Red Crescent Societies

11

Dichato, Chilean Earthquake and Tsunami

Feb. 27,2010

Photo: The International Federation of Red Cross and Red Crescent Societies

11

Dichato Chilean Earthquake and Tsunami Feb. 27,2010

Photo: The International Federation of Red Cross and Red Crescent Societies

11

@Heavy

damage in low-

lying area near

a river

@only 18 dead

among 4000

residents

01

234

56

78

0 50 100 150 200 250 300 350 400 450 500

La plaza y el muelle.

Robinson Crusoe Island: Before and after the Tsunami

Magnitude of Earthquake and Tsunami

M7

limited Local Tsunami

M8

Large Regional Tsunami

M9

Huge Ocean Tsunami

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.

Tsunami Disasters Place Casualties

2011 Tōhoku Earthquake and Tsunami Japan 20,000

2004 Indian Ocean Tsunami Indonesia 220,0000

1908 Messina Earthquake (Landslide) Italy 70,000

1896 Meiji-Sanriku Earthquake Japan 22,000

1883 Eruption of Krakatoa Indonesia 36,000

1868 Arica Earthquake Chile 25,000

1792 Unzen Eruption and Earthquake

(Landslide tsunami) Japan 10,000

1771 Great Yaeyama Tsunami Japan 13,000

1755 Lisbon Earthquake and Tsunami Portugal 100,000

1707 Hōei Earthquake and Tsunami Japan 30,000

Summary of Major Tsunami Disasters

Experimental studies on tsunami damage

Prototype Experiments in Large Hydro-Geo Channel to

investigate tsunami damages

Destruction of a wooden house

Destruction of a Wooden House

Destruction of Concrete Wall

Collision of Container

Tsunami Force on Evacuation Building

Stability of Human Body against Tsunami

Simulation of Tsunami intrusion into a port

town

Numerical simulation on tsunami inundation

using a super computer (Arikawa)

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

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 andbridges

subsidance of ground

Inundation of rice paddles

Drifting and collision of ships

Destruction and inundation of portfaciliteis

Drifting and collision of timbers andcontainers

Debris deposit in ports

Scouring and deposit in ports

Scouring of sandy beaches anddestruction of green belts

Destruction of acuaculture facilities

Scouring and sliding of Breakwaters andquaywalls

Destruction of jetties and detachedbreakwatersDestruction (scouring) of Dykes andSeawallsDestruction of water gates

Gene

ral

Port

s an

d Co

asts

Coa

stal

Def

ense

s

10m tsunami

damage

Difference of Water Level (Sliding of Wall)

Rapid Current (Scattering and Scouring)

Wave Impact (Seawall Failure

Rapid Current (Seawall Scouring and Overturning)

Typical Damages to Tsunami Defenses

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.

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.

3.Tsunami Disaster Mitigation

@non-structural countermeasures

@ Structural countermeasures

We need to improve our preparedness by non-

structural and structural countermeasures.

We have to improve our town to be

resilient to Tsunami disaster.

Reduce the casualties into zero

Resilient town

= Ensure early recovery

= Reduce damage

Improvement of Preparedness

What is the most significant difference

between Earthquake and Tsunami

Attacks?

We can have a time for evacuation against tsunami attack !

We can reduce the casualty by tsunami into zero by proper evacuation.

TIME

Non-structural Countermeasures

1.Effective Evacuation

@Tsunami Warning System

@ Hazard Map

@ Evacuation Facilities(Building,Tower etc)

2.Dissemination of Tsunami Knowledge

3. Land Usage Planning

• 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!

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

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.

GPS Buoy

(Wave andTsunami Meter)

satellite GPS

Tsunami

Meter

Tsunami

Data

GPS buoys for wave and tsunami

observation by MLITT

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

Improvement of Evacuation Methods

Evacuation Buildings

High Lands and Evacuation Towers

Tsunami Evacuation

= Vertical Evacuation

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.

Improvement of Evacuation

Not Horizontal but Vertical Evacuation

5 Minutes Evacuation by Emergency Refuge using High Buildings

Modern concrete

buildings were

inundated but

remained.

Manual for Tsunami and Storm Surge

Hazard Map

Tsunami Hazard Map of Suzaki Bay

Suzaki City

Hazard Map Workshop by Stakeholders

Other measures for safe evacuation

Seminars and Lectures for disaster education

Transmission of tsunami experience

Installation of Evacuation sign boards

Improvement of evacuation places

Improvement of evacuation routes

Preparation of evacuation building

Meiji-Sanriku Tsunami Disaster Monument

A Book to memorize Showa- Nankai Tsunami

(1946) at Kainan Town for their descendants

Tsunami Books

Temporary Evacuation Place i n Tanabe Town

Emergency

Vertical

Evacuation

Evacuation Tower (Taiki Town)

5 Minutes Evacuation = Vertical Evacuation

88

沿岸部低地での

津波防災まちづくり(イメージ)

Resilient Coastal Towns

Disaster reduction (mitigation) to ensure early recovery

Compact Coastal Towns by House Relocation into high lands

and High Buildings near Coasts

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.

Laws for Coastal Disaster Prevention

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

History of Disaster Prevention Acts

In 1978, Large Scale Earthquake Countermeasure Special Act

( Basic plan for earthquake disaster prevention) @Definition of jurisdictions and responsibilities for

disaster management @Disaster management system and plan @Disaster preparedness @Emergency actions and recovery @Financial measure @State of emergency

Structural Countermeasures

Tsunami Seawalls Tsunami Dike Tsunami Breakwater Tsunami Gate Artificial High Ground

Houei Nankai

1707

Ansei Nankai

1854

Showa

Nankai 1946

Tsunami Dike by

Hamaguchi

Hiro Village 1855-

1857

From HP of Hirokawa-Town

Inundation areas

due to Ansei Nankai 1854 Showa Nankai 1946

From HP of Hirokawa-Town

Taro Town Before 1933Tsunami(Showa Sanriku Tsunami)

From HP of Miyako City

Taro Town Aftere 1933 Tsunami(Showa Sanriku Tsunami)

From HP of Miyako City

TARO Town (Miyako City)

1611/1896/1933

Tsunami wall TP10m

Total 2433m(1934-1988)

Tsunami Seawall

Tsunami Gate

Tsunami Gate

Aonae Disrict of Okushiri Island

Hokkaido Nansei-Oki(M 7.7)【1993】

Land use planning in Aonae District

Tsunami Countermeasures (Aonae District)

New Town

Park

ReclamationSeawall

Completed tsunami mitigation works

In Aonae Fishery Port Area

Artificial High Ground11m seawall

6m Seawall

Fishery Port

Kuji

Kamaishi

Ofunat

Suzaki

Shimoda

Tsunami Breakwaters

Kamaishi Bay-mouth Breakwater

North 990m South 670m

Opening 300m 1988-2007

New Tsunami Mobile Gate ( Air Cylinders)

New Tsunami Mobile Gate- Flap gate

Green-Belt (Coastal Forests)

Study on Coastal Forests against Tsunami

Tsunami Risk Assessment

Risk=Hazard x Vulnerability

Vulnerability = Ground Height

Population

Economic Activities

Preparedness

Scenario based risk assessment

Disaster Scenarios of

@Earthquake /Tsunami

@Warning and Evacuation

@Inundation/Damages/Secondary Damage

@Rescue

@Recovery

First, we should write a disaster scenario

(what will actually occur) if we have Level 1

tsunami or Level 2 tsunami now.

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.

Improvement of preparedness

Concluding Remarks

International Workshop on Coastal

Disaster Prevention

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.

Summary of the 4th 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 effec-

tive evacuation and prevention of losses.

International cooperation and collabora-tion

including sociologists are needed to develop and

use the technology effectively.

Summary of the 4th 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.

Summary of the 4th International Workshop on Coastal Disaster

Prevention (Direction of tsunami disaster mitigation)

The seas are beautiful and rich.

Coastal Disaster Mitigation with

our wisdom and modern technology

Live together with Rich but Violent Seas

Thank you for your attention

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. 31.

Email : [email protected]

Assignment