Tsunami
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TSUNAMI BASICS
Review Chapter One: Tsunami Basics and complete the following workbook.
WHAT IS A TSUNAMI?
[A. Tsunami events are usually associated with earthquakes, volcanic eruptions and
landslides, which can cause a sudden movement of the water column in the ocean, and
create fast-moving waves.]
WHAT DOES THE WORD TSUNAMI MEAN?
[A. Tsunami is a Japanese word that translates as ‘harbour wave’.]
WHERE DO MOST EARTHQUAKES AND VOLCANOES OCCUR ON EARTH’S
SURFACE?
[A: Along fault lines at the edge of Earth’s tectonic plates.]
WHAT IS SUBDUCTION?
[A: Subduction occurs on Earth’s crust where two tectonic plates meet. When one plate
moves under the other plate it sinks into the mantle and forces the other plate upwards
causing an earthquake.]
WHY IS SUBDUCTION RELEVANT TO TSUNAMI?
[A: Typically, large tsunami waves are created by underwater earthquakes that occur along
subduction zones.]
WHAT CAUSES MOST TSUNAMI EVENTS?
Match the tsunami cause to the pie chart:
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Earthquakes
Unknown
Volcanoes
Weather events
Landslides
Credit: NOAA/Surf Life Saving Australia
[A: 77% earthquakes, 10% unknown, 6% volcanoes, 4% weather events and 3%
landslides]
WHERE DO MOST TSUNAMI EVENTS HAPPEN?
[A: Indian and Pacific oceans]
DESCRIBE THE RING OF FIRE AND ITS RELATIONSHIP TO TSUNAMI EVENTS:
[A: The edges of the tectonic plates in the Ring of Fire interact to form highly active seismic
belts. Most of the world’s tsunami events originate in the area.]
On this map, show the location of the Ring of Fire:
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Credit: Geoscience Australia/Surf Life Saving Australia
THERE ARE THREE STAGES IN A TSUNAMI EVENT. PUT THEM IN ORDER AND
EXPLAIN WHAT THE TERMS MEAN:
Inundation [A: 3. Overflow of water onto the land, which can be very dangerous and
destructive.].
Generation [A: 1. Caused by any force that disturbs a water column.]
Propagation [A: 2. The displaced water moves across the deep ocean.]
HOW FAST DO TSUNAMI WAVES TRAVEL IN THE OPEN OCEAN?
[A. 640-960 km per hour.]
HOW HIGH ARE TSUNAMI WAVES IN THE OPEN OCEAN?
[A: Not very high; 20–50 cm.]
HOW FAR APART ARE TSUNAMI WAVES IN THE OPEN OCEAN?
[A. Very far apart; they can be hundreds of kilometres apart.]
EXPLAIN WHAT DRAWBACK MEANS:
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[A: As a tsunami approaches shore, the water draws back from the coast further than
normal.]
WHAT IS SHOALING?
[A: As waves approach shallow water, they slow down, increase in height and get closer
together.]
Draw a picture of shoaling:
Credit: Geoscience Australia
HOW ARE TSUNAMI AND WIND WAVES DIFFERENT?
[A: Tsunami waves move an entire column of water from the ocean floor to its surface and
can be hundreds of kilometres apart. Waves generated by wind only move across the
surface of the ocean and are usually just a few metres apart.]
A TSUNAMI IS ONE GIANT WAVE. TRUE / FALSE
[A: False. A tsunami is a series of waves.]
DISCUSS
A tsunami in open water is barely perceptible but can reach great heights
as it approaches land. Why?
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AUSTRALIAN TSUNAMI
IMPACTS
Review Chapter Two: Australian Tsunami Impacts and complete the following workbook.
DOES AUSTRALIA EXPERIENCE TSUNAMI? YES / NO
[A: yes]
WHAT SORT OF TSUNAMI IS MOST LIKELY TO OCCUR IN AUSTRALIA?
[A: Australia will most likely experience the effects of marine threat tsunami, which include
dangerous rips, waves and strong currents. Land threat tsunami are rare but extremely
hazardous and can cause inundation in low-lying coastal regions.]
FROM WHERE WILL TSUNAMI THAT REACH AUSTRALIA MOST LIKELY COME?
[A: Australia is susceptible to tsunami events (caused by undersea earthquakes) from the
north-west and east where 8000 km of tectonic plate boundaries contain particularly active
subduction zones.]
HOW QUICKLY WILL A TSUNAMI REACH MAINLAND AUSTRALIA AFTER AN
UNDERSEA EARTHQUAKE?
[A: The fastest time a tsunami could reach Australia is around 2 hours.]
WHAT ARE TSUNAMI MODELS USED FOR?
Credit: Bureau of Meteorology
[A: Scientists use models to calculate the height and direction of tsunami waves from
potential undersea earthquakes. They use the models to determine the possible tsunami
threat to Australia when an actual undersea earthquake is detected.]
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WHICH TRENCHES PRESENT POTENTIAL TSUNAMI THREATS
TO AUSTRALIA?
Label them on this map:
Credit: Geoscience Australia /Surf Life Saving Australia
HOW MANY TSUNAMI EVENTS HAVE THERE BEEN IN AUSTRALIA
SINCE 1788?
[A: More than 50.]
HOW DID THE 2006 JAVA TRENCH TSUNAMI IMPACT AUSTRALIA?
[A: It hit parts of Western Australia, particularly Steep Point on the central west coast. It
quickly flowed inland 200 m and 8 m above mean sea level. There was widespread
erosion, extensive vegetation damage and several campsites were destroyed. Campers at
Steep Point were lucky to escape when the tsunami inundated their campsite, picked up
their four-wheel drive vehicle and moved it 10 m up the beach.]
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WARNING SYSTEM
Review Chapter Three: Warning System and complete the following workbook.
WHICH ORGANISATIONS ARE INVOLVED IN THE AUSTRALIAN TSUNAMI WARNING
SYSTEM?
[A: The Bureau of Meteorology, Geoscience Australia and the Attorney-General’s
Department. They liaise with emergency services and the media.]
WHAT ORGANISATION IS THE AUTHORITY FOR TSUNAMI WARNINGS IN
AUSTRALIA?
[A. The Joint Australian Tsunami Warning Centre.]
THERE ARE SEVERAL STAGES IN A TSUNAMI WARNING.
Put the following steps in order.
1. An earthquake is detected by Geoscience Australia (Detect)
2. Scientists at the Bureau of Meteorology review data from Geoscience Australia to
determine if a tsunami has been generated. (Assess)
3. The Bureau of Meteorology uses models to predict the height, speed and direction of a
potential tsunami. (Assess)
4. The Joint Australian Tsunami Warning Centre issues a Watch or No Threat bulletin.
(Advise)
5. The Joint Australian Tsunami Warning Centre liaises with partners in the Australia Tsunami
Warning System. (Inform)
6. The Joint Australian Tsunami Warning Centre monitors the tsunami detection network.
(Monitor)
7. The Joint Australian Tsunami Warning Centre upgrades the Watch to a Warning. (Revise)
8. The Joint Australian Tsunami Warning Centre cancels the Warning. (Close)
Match the steps to the stages in the warning cycle:
1. Detect
2. Assess
3. Advise
4. Inform
5. Monitor
6. Revise
7. Close
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WHAT INSTRUMENTS DOES GEOSCIENCE AUSTRALIA USE TO DETECT
EARTHQUAKES?
[A: Seismometers]
HOW QUICKLY CAN THE JOINT AUSTRALIAN TSUNAMI WARNING CENTRE ISSUE
TSUNAMI WARNINGS AFTER AN EARTHQUAKE?
10 minutes
30 minutes
1 hour
2 hours
[A: Within 30 minutes of an earthquake being detected.]
WHAT MONITORING NETWORKS DOES THE JOINT AUSTRALIAN TSUNAMI
WARNING CENTRE USE TO DETECT TSUNAMI EVENTS?
[A: Seismic network, coastal sea level monitoring system and deep-ocean tsunami
detection stations.]
EXPLAIN HOW TSUNAMI DETECTION BUOYS WORK:
[A. Deep-ocean tsunami detection stations include a buoy on the surface and a pressure
sensor many kilometres below on the ocean floor. The sensor measures the change in
height of the water column above by measuring associated changes in the water pressure.
Changes in the height of the water column are communicated to the surface buoy and then
relayed via satellite to the tsunami warning centre.]
WHAT WEBSITE SHOULD YOU CHECK FOR TSUNAMI WARNINGS IN AUSTRALIA?
[A: www.bom.gov.au/tsunami]
WHAT ARE THE FIVE LEVELS OF TSUNAMI WARNINGS?
Identify the warning levels on this map:
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Credit: Bureau of Meteorology
TO WHICH INTERNATIONAL TSUNAMI WARNING SYSTEMS DOES AUSTRALIA
BELONG?
[A: Indian Ocean Tsunami Warning and Mitigation System and Pacific Ocean Tsunami
Warning and Mitigation System.]
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MARINE THREAT TSUNAMI
Review Chapter Four: Marine Threat Tsunami and complete the following workbook.
WHAT IS A MARINE THREAT TSUNAMI?
[A: Marine threat tsunami can generate dangerous rips, waves and strong currents that
pose a risk to surfers, swimmers, people in small boats and anyone else in the water.
There may be some localised flooding onto the immediate foreshore.]
WHAT SHOULD YOU DO IF THERE IS A MARINE THREAT TSUNAMI WARNING?
[A: Get out of the water immediately and move away from the water’s edge. Boats in
harbours should return to shore. Boats at sea should stay offshore in deep water. Once
you’re in a safer location, monitor the radio, TV or internet for information. Don’t return to
the water until you receive official advice that it is safe to do so.]
IF I’M SWIMMING WHEN A MARINE TSUNAMI COMES, I COULD GET DRAGGED OUT
TO SEA BY STRONG RIPS OR CURRENTS. TRUE / FALSE
[A: TRUE]
CASE STUDY: 2010 HAWAII MARINE THREAT TSUNAMI
Research the case study further. List the ways in which Hawaii was impacted by the
marine threat tsunami. Fill in the table below:
Environmental
Social Impacts
Impacts
(e.g. people, health,
(e.g. flora, fauna,
food)
air, water, terrain)
Economic Impacts
(e.g. income, jobs
business,
government
expenses)
Other
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LAND THREAT TSUNAMI
Review Chapter Five: Land Threat Tsunami and complete the following workbook.
WHAT IS A LAND THREAT TSUNAMI?
[A: A land threat tsunami can cause major land inundation, flooding to low-lying coastal
areas, dangerous waves and strong ocean currents.]
HAS AUSTRALIA EXPERIENCED LAND THREAT TSUNAMI? IF SO, WHEN?
[A: Yes. Most recently, the 1994 and 2006 Java tsunami events caused land inundation in
low-lying coastal areas.]
WHAT SHOULD YOU DO IN A LAND THREAT TSUNAMI WARNING?
[A: Go to higher ground, at least 10 m above sea level, or, if possible, move at least 1 km
inland away from coastal areas. If you cannot leave the area, take shelter in the upper
storey of a sturdy brick or concrete multi-storey building. Boats in harbours should return to
shore. Boats at sea should stay offshore in deep water. Once you’re in a safer location,
monitor the radio, TV or internet until you receive official advice that it is safe to return.]
CASE STUDY: 2011 JAPAN LAND THREAT TSUNAMI
Research the case study further. List the ways in which Japan was impacted by the land
threat tsunami. Fill in the table below:
Environmental
Social Impacts
Impacts
(e.g. people, health,
(e.g. flora, fauna,
food)
air, water, terrain)
Economic Impacts
(e.g. income, jobs
business,
government
expenses)
Other
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PREPARING FOR TSUNAMI
Review Chapter Six: Preparing for Tsunami and complete the following workbook.
WHAT SHOULD YOU DO TO BE PREPARED FOR A TSUNAMI?
[A: Be aware of what you might experience before a tsunami hits, have an emergency kit
and have a tsunami action plan.]
WHICH ORGANISATION IS THE AUTHORITY FOR TSUNAMI WARNINGS IN
AUSTRALIA?
[A. The Joint Australian Tsunami Warning Centre.]
WHAT WEBSITE SHOULD YOU CHECK FOR TSUNAMI WARNINGS IN AUSTRALIA?
[A: www.bom.gov.au/tsunami]
WHAT PHONE NUMBER CAN YOU CALL FOR TSUNAMI WARNINGS IN AUSTRALIA?
[A: 1300 TSUNAMI or 1300 878 6264.]
THERE ARE THREE MAIN SIGNS OF A TSUNAMI, DESCRIBE THEM:
FEEL [A: If you’re near the shore and you feel the ground shake, a tsunami may have
been caused by a nearby earthquake.]
SEE [A: If you see the ocean water draw back from a beac
h, bay or river, a tsunami may be on its way.]
HEAR [A: If you hear a loud roaring sound or see a wave coming, a tsunami may be on its
way.]
CAN TSUNAMIS HAPPEN ON ANY COAST?
[A: Yes.]
DO ALL COUNTRIES HAVE TSUNAMI WARNING SYSTEMS?
[A: No.]
IF YOU’RE TRAVELLING OVERSEAS, WHICH WEBSITE SHOULD YOU CHECK BEFORE
YOU LEAVE TO LEARN ABOUT THE RISK OF TSUNAMI?
[A: DFAT Smart Traveller website (www.smartraveller.gov.au).]
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CASE STUDY: 2004 INDIAN OCEAN TSUNAMI
Research the case study further. List the ways in which Indian Ocean countries were
impacted by the tsunami. Fill in the table below:
Environmental
Social Impacts
Impacts
(e.g. people, health,
(e.g. flora, fauna,
food)
air, water, terrain)
Economic Impacts
(e.g. income, jobs
business,
government
expenses)
Other
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