Transcript Be Tsunami Smart

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?
 Tsunami => tsu (harbor) + nami
(wave).
 Tsunami => 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”
ANIMATION
Terminology
 Wavelength: the distance from one crest of the tsunami to the
next
 Inundation: the maximum distance inland from the normal coastline
reached by the tsunami or maximum area covered by the water
 Runup: maximum height onshore reached by tsunami
Tsunamis evolve through 3 stages;
3. INUNDATION
2. PROPOGATION
1. GENERATION
REFRACTION
Refraction and shoaling funnel the waves
energy into a dangerously high wall of water
SHOALING
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 Threats
 Local/Regional:
 Generated nearby
 Strikes shore quickly (in minutes)
 NO TIME for official evacuation
 Education & Awareness
 Recognize the warning signs
 Distant/Ocean-wide/Tele-tsunamis
 Generated far away, instr detection
 Strikes shore later (2+ hours)
 TIME for official evacuation
 Widespread Damage
 Tsunami Warning Center => people-centered
response with locally-guided safety actions
Volcanic eruptions
Volcanic eruptions may cause
tsunamis in a number of ways - all
impact the water to create
displacement of the ocean
generating tsunami waves.
Lateral blasts
Debris avalanche
Explosions, pyroclastic flows
….could trigger tsunamis.
Submarine Volcanic eruptions
•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 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 landslidegenerated tsunami , located off the northern coast of Guadeloupe, part of a farreaching 1867 earthquake event.
Artist
impression
Artist
impression
Other possible causes
 Cosmic-body impacts such
as:
 Asteriods
 Meteorites
 Comets
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 hundred
thousand years!
Be Tsunami Smart!
Implement an End-to-End System
 Checklist:
Components of a Hazard Reduction Strategy
 Assessment:
 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 Smart
Be Tsunami Smart
Before a Tsunami
 Know how far you are from the coast
 Learn the quickest route to get to high
ground
 Ensure that you and your family know how
to detect tsunami signs
 Have an emergency plan and emergency
supplies
BEFORE
Be Tsunami Smart
Sensing a Tsunami
Tsunamis can sometimes be
detected by its natural
warning signs using human
senses.
FEEL
Do you FEEL the ground
shaking so severely that
standing is difficult?
FEEL
Be Tsunami Smart
SEE-HEAR
SEE
Do you SEE an unusual withdrawal
of the sea exposing rocks, reefs or
fish?
HEAR
Do you HEAR the loud roar of the waves?
Be Tsunami Smart
•Often the first sign is an Earthquake
•Followed by a withdrawal of the sea.
Sri Lanka, 26th December 2004
Image shows “drawback” or withdrawal of water exposing ~150 meters of temporary beach
Photo: www.digitalglobe.com
Then returns like
a rapidly-rising tide.
Be Tsunami Smart
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.
Remember the first wave may NOT be the last or largest.
RUN
Be Tsunami Smart
DO NOT RETURN
If you
FEEL,
SEE,
HEAR a tsunami coming RUN
The first surge of a
tsunami is often not
the largest.
Do not return to the
beach until the “AllClear” is issued by
authorities.
RUN for high ground as fast as you can!
Be Tsunami Smart
During a Tsunami
 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.
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 Smart
After a tsunami
 Stay tuned to a battery operated radio for the latest emergency
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information
Help 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 department
Throw out perishable and contaminated food items.
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!