Understanding…

To promote scientific understanding and safety in the Caribbean.

Seismic Research Centre

Monitor – Earthquakes, Volcanoes, Tsunamis

Mitigate – Provide contributing governments with maps and information on geologic hazards.

Educate – Support disaster management agencies with public education efforts.

What are they?

TsunamiTsunami => tsu (harbor) + nami (wave).

TsunamiTsunami => a series of ocean waves caused by an abrupt disturbance of the ocean floor that displaces a large mass of water.

Waves radiate outward in all directions from the disturbance, and can propagate across entire ocean basins.

NOT a “tidal wave”NOT a “tidal wave”

ANIMATION

WavelengthWavelength: the distance from one crest of the tsunami to the next

InundationInundation: the maximum distance inland from the normal coastline reached by the tsunami or maximum area covered by the water

RunupRunup:: maximum height onshore reached by tsunami

Terminology

1. GENERATION

2. PROPOGATION

3. INUNDATION

Tsunamis evolve through 3 stages;

Refraction and shoaling funnel the waves energy into a dangerously high wall of water

SHOALING

REFRACTION

Earthquakes

Tsunamis are primarily associated with earthquakes occurring below or near the ocean floor.

Earthquakes generate tsunamis when the sea floor abruptly shifts causing a sudden displacement of the overlying water from its equilibrium position.

Waves form as the displaced water mass, which acts under the influence of gravity, attempts to regain its equilibrium.

Source of ThreatsLocal/Regional:

Generated nearbyStrikes shore quickly (in minutes) NO TIME NO TIME for official evacuation

Education & Awareness Recognize the warning signs

Distant/Ocean-wide/Tele-tsunamisGenerated far away, instr detection Strikes shore later (2+ hours) TIMETIME for official evacuation

Widespread Damage Tsunami Warning Center => people-centered

response with locally-guided safety actions

Volcanic eruptions may cause tsunamis in a number of ways - all impact the water to create displacement of the ocean generating tsunami waves.

Volcanic eruptions

Explosions, pyroclastic flows

Lateral blasts

….could trigger tsunamis.

Debris avalanche

•Violent submarine volcanic eruptions can create an impulsive force that uplifts the water column and generates a tsunami.

•The eruption of Kick ‘em Jenny submarine volcano on July 24 1939

generated a tsunami which had an amplitude of 1-2 meters in Northern Grenada,

Southern Grenadines Barbados – run up was sufficient enough to flood roads

on the west coast.

•Another Kick ‘em Jenny eruption on October 30, 1965, produced a minor tsunami.

Background photo: Submarine volcanic eruption off the coast of Tonga (March 2009)

Submarine Volcanic eruptions

Submarine Landslides

Tsunamis generated are usually, though not always, associated with earthquakes and volcanic eruptions.

Since the source of landslides is near shore - the warning time may be only a few minutes.

Can occur when a tectonic trigger causes the ocean floor to slump or when huge chunks of glaciers, volcanoes or other debris slides crash into the sea.

When the ocean bottom crumbles in an underwater landslide, the moving dirt can push water in front of it and create a tsunami wave.

Whether they are submarine or coastal, landslides can cause massive tsunamis and have devastating local effects.

The largest tsunami ever reported in the Caribbean was probably a landslide-generated tsunami , located off the northern coast of Guadeloupe, part of a far-reaching 1867 earthquake event.

Cosmic-body impacts such as: AsteriodsAsteriods MeteoritesMeteorites CometsComets

can also disturb the water but from above, as momentum from falling debris is transferred to the water being displaced

Evidence suggests that an impact on the order of a 10-megaton explosion could occur once every few hundredhundred thousand years!thousand years!

Other possible causes

Artist impressionArtist impression

Be Tsunami Smart!

Implement an End-to-End SystemChecklist:Checklist:

Components of a Hazard Reduction StrategyAssessment:

Historical studies, field surveys, numerical simulation (bathymetry), GIS DB => historical database, inundation maps, risk & vulnerability, evacuation maps

Warning Guidance:Monitoring networks, numerical simulation => early

detection, real-time data, wave forecast, warning dissemination

Mitigation - Preparedness:Education, Communication, Planning & Preparedness,

Engineering (Structural/Non-Structural) Be Tsunami SmartBe Tsunami Smart

BeforeBefore a TsunamiKnow how far you are you are from the coast

Learn the quickest routequickest route to get to high ground

Ensure that you and your family know how know how to detect tsunami signsto detect tsunami signs

Have an emergency plan and emergency supplies

Be Tsunami SmartBe Tsunami SmartBEFOREBEFORE

Tsunamis can sometimes be detected by its natural warning signs using human senses.

FEELFEELDo you FEEL the ground shaking so severely that standing is difficult?

SensingSensing a Tsunami

Be Tsunami SmartBe Tsunami SmartFEELFEEL

SEESEEDo you SEE an unusual withdrawal of the sea exposing rocks, reefs or fish?

HEARHEARDo you HEAR the loud roar of the waves?

Be Tsunami SmartBe Tsunami SmartSEE-HEARSEE-HEAR

•Often the first sign is an Earthquake•Followed by a withdrawal of the sea.

Sri Lanka, 26th December 2004Image shows “drawback” or withdrawal of water exposing ~150 meters of temporary beachPhoto: www.digitalglobe.com

~150m withdrawal of the sea

Be Tsunami SmartBe Tsunami Smart

Then returns like a rapidly-rising tide.

Never go to the beach to wait and watch for a tsunami.Never go to the beach to wait and watch for a tsunami.

If you can see the wave, you are already too close to outrun it.If you can see the wave, you are already too close to outrun it.

Remember the first wave may NOT be the last or largest.Remember the first wave may NOT be the last or largest.

Be Tsunami SmartBe Tsunami SmartRUNRUN

The first surge of a tsunami is often not the largest.

Do not return to the beach until the “All-Clear” is issued by authorities.

If you FEEL, SEE, HEAR a tsunami coming RUN

RUN for high ground as fast as you can!

Be Tsunami SmartBe Tsunami SmartDO NOT RETURNDO NOT RETURN

During a Tsunami

A survivor re-enacts his escape from the wave by climbing a small tree on one of the islands of Papua New Guinea 1998

Be Tsunami SmartBe Tsunami Smart

Tsunamis may occur without the initial pulling back of the sea. In this case, a massive wall of water may be seen approaching the

coast. If you cannot get to higher ground go to:

an upper floor/roof of a building or climb a tall strong tree.an upper floor/roof of a building or climb a tall strong tree.

After a tsunamiStay tuned to a battery operated radio for the latest emergency

informationHelp injured or trapped persons and persons requiring special

assistance (infants, elderly)Do not move seriously injured persons unless they are in

immediate danger of further injury. Call for medical assistance.Stay out of damaged buildings. Check for electrical shorts and live wires, gas leaks, damage to

sewage and water lines.Check food supplies and have tap water tested by the local

health departmentThrow out perishable and contaminated food items.

Be Tsunami SmartBe Tsunami Smart

Remember•Practice evacuation plans with your friends and family.

•Teach your friends and family about the tsunami hazards and natural warning signs

•Always keep an emergency supply stock of items like first aid kit, canned foods, clean water and batteries for flashlights or radios.

As dangerous as tsunamis are they do not happen very often.

You should not let this hazard diminish your enjoyment of the beach and beauty of the ocean.

But if you think a tsunami is coming, tell your friends and relatives and move quickly inland and to higher ground!