Tsunami ppt

TSUNAMI MITIGATIONTSUNAMI MITIGATION
AND MANAGEMENTAND MANAGEMENT
By-
o
( )

PART-IPART-I
NITTY GRITTY OF TSUNAMI

TSUNAMI BASICSTSUNAMI BASICS
• Term Tsunami a Japanese word means Port
Wave
• Defined as a Wave Train generated by the
impulsive disturbances of a water body caused
by displacement due to:
• Sea quake
• Volcanic eruption
• Landslide/subsidence in the ocean

WAVE CHARACTERISTCSWAVE CHARACTERISTCS
Parameters govern size and occurrence:
• Fault Mechanism
• Depth of Focus
• Proximity of source of Earthquake

FAULT MECHANISMFAULT MECHANISM
• Mega earthquakes (M>8) associated both
vertical and horizontal movements
• Net displacement-movement in both
components
• Huge displacement of water is essential
• Vertical movements likely to generate
more Tsunamis
• Strike slip can cause Ts lesser magnitude

OTHER PARAMETERSOTHER PARAMETERS
• Depth of Focus:
• Shallow for large magnitude EQ – Large
Tsunami
• Tsunamigenic source may be near field or far
field
• Near field < 2500 km
• Far field > 2500 km
• Normally mega Eqs associated with Megathrust
events,occurring where one tectonic plate
subducts beneath another.

WAVE DYNAMICSWAVE DYNAMICS
• Ts energy flux based on wave speed and height
• Ts speed diminishes in shallow water but height grows
up
• In open sea wavelength very large with low amplitude
• Closer to shore it is reverse
• Kinetic energy of waves transformed in potential energy
near the shore
• Velocity can reach upto 800km/hr
• Ts is governed by shallow water wave dynamics
• Ocean floor configuration and bathymetry controls and
modifies its propagation characteristics
• Ts not only propagate at high speeds but also can travel
great distance with limited energy loss

WAVE DYNAMICSWAVE DYNAMICS
• When waves of Ts approach land their
appearance and behaviour dependent on
several factors
• Important being topography of the sea
floor and shape of the shoreline
• Wave hts increased in bays, river mouth,
lagoons and creeks
• Off-shore coral reef can dissipate the
energy

TSUNAMI PARAMETRESTSUNAMI PARAMETRES
• Following parameters required to assess the
impact of Tsunami:
• Tsunami magnitude (Tm) :Estimated or
calculated Tm =log.H (run up in m.)
• Wave Height : Actual ht of Ts recorded by tidal
gauge
• Run up(H) : Maximum vertical ht. on land Ts
reached above msl
• Tide State : Run up ht. during high tide> and
less during low tide

PART-IIPART-II
INDIAN OCEAN TSUNAMI
26th
December,2004

INDIAN OCEAN TSUNAMIINDIAN OCEAN TSUNAMI
2626thth
December,2004December,2004
• On the morning of 26th
Dec.2004,eastern
hemisphere was struck a major natural
catastrophe, Tsunami
• Shell shocked everyone with a palm of
gloom with unprecedented destruction in
vast areas of India and adjoining SE Asian
countries

EARTHQUAKE AND TSUNAMIEARTHQUAKE AND TSUNAMI
EPISODEEPISODE
• A shallow EQ of M 9+ stuck the coast off Sumatra at
around 30km on 26th
De,2004 at around 0630hrs
• Epicentre located 260km SSE of Banda
Aceh,Indonesia
• Major EQ was followed by a number of after shocks
• EQ triggered the Tsunami
• Unleashed vast devastation all along the littoral countries
fringing Indian Ocean
• More than 1.5lakh people lost lives and property worth
millions lost and several thousands rendered homeless

EARTHQUAKE AND TSUNAMIEARTHQUAKE AND TSUNAMI
EPISODEEPISODE
• Tsunami stuck different stretches at different
timings mainly based on distance from the
epicentral location
• Ts recorded in Andaman Nicobar islands at
around 0725hrs
• Chennai coast at around 0845hrs
• Nagapattinam coast at around 0900hrs
• Kanyakumari coast at around 1230hrs
• Tuticorin at around 1330 hrs
• West coast at Kayamkulam at around 1230hrs.

FINDINGS OF DISCOVERYFINDINGS OF DISCOVERY
CHANNEL SURVEYCHANNEL SURVEY
• Study proved it as a mega thrust faulting at the
epicentre- a large scale rupturing and vertical
displacement which generated the Tsunami
• Indian plate moving at the rate of 5cm every
year subducted deep under the Burma plate
• Continuous subduction of Indian plate built up
enormous stress on Burma plate
• At breaking point accumulated stress released
in the form EQ

IMPACT SURVEY-IMPACT SURVEY-THE AREATHE AREA
• Coastline between Nagapattinam
and Kanyakumari, Tamil
Nadu,South India, fringing the east
coast (480 km)
Sectors
• Nagapattinam – Point Calimere (57
km)
• Point Calimere – Ramanathapuram
(190 km)
• Ramanathapuram – Rameswaram –
Tuticorin (113 km)
• Tuticorin – Tiruchendur (35 Km)
• Tiruchendur – Kanyakumari(85 km)

IMPACT SURVEY-IMPACT SURVEY-
OBJECTIVESOBJECTIVES
Post Tsunami Impact Assessment
• Measurement of Run-up elevation and run-up length
• Soil
• Ground water
• Geothermal springs
• Corals and marine life
• Monuments and temples
• Social life
• Classification of zones depending on severity of impacts
both to loss of lives and damage to property
Formulation of Disaster Management Plan(DMP)

IMPACT SURVEYIMPACT SURVEY
Nagapattinam-Point Calimere Sector (I)Nagapattinam-Point Calimere Sector (I)
• A 57 km N-S coastal
stretch lying to the south
of Karaikal
• Coastline consists of 10-
30m wide sandy beach,
1.5 to 3.0 km wide recent
dune complex
• Two to three dune ridges
of 3-5 m height run along
the coast and coalesce to
form compound dune
complex

Nagapattinam-Point Calimere Sector(I)Nagapattinam-Point Calimere Sector(I)
• A huge loss of life and
property reported in this
sector
• 6000+ people have
simply been washed
away.

• Closely berthed boats in
the fishing jetty-
Nagapattinam, collided
due to the tsunami waves
• Many lifted and perched
over the bridge
• Some thrown inside the
adjoining fisherman
colony

• Flattening of beach
• Heavy siltation
(tsunami deposit) in
Vettar, Uppanar and
Vellar rivers

• Loss of life and damage
to property comparatively
less between Velanganni
and Point Calimere
• Due to the presence of
linear/wide barrier sand
dunes along the coast,
wide beach and thick belt
of plantations near
Pattanavarnattam and
Point Calimere sanctuary.

• The tsunami wave arrived by
09: 20 hrs
• Hit the coast at an acute angle
• Wave splash on hitting the
coast rose up to 8-10m.
• Post- tsunami survey indicates
run-up elevation from 2 to
3m
• Run-up length varied from 0.2
to 1.25 km depending on the
coastal geomorphologyRun up length

Nagapattinam-Point Calimere Sector(I)Nagapattinam-Point Calimere Sector(I)
• Maximum inundation by seawater of the order of
0.5 to 1.2 km in the low-lying stretch between
Pattanchcheri and Nagapattinam
• Causing damage to topsoil and ground water
• Shoreline appears to have transgressed a few
meters inland in this segment

• Cause behind the major tragedy in this sector is
mainly due to the dense population/inhabitations
seen along coast especially between Nagore in
the north and Velanganni in the south
• In addition, the area falls within the low lying
zone, wrapped around by the distributaries of
Cauvery delta causing much sea water
inundation
• Lack of major geomorphic features like
elevated/wide beach, distinct barrier dunes to
protect against the fury of killer waves.

Disaster Rating
• Considering heavy loss of life and
property, the sector is categorized as the
heavily damaged zone (Vulnerable
Zone).

Ramanathapuram –Rameshwaram-Tuticorin Sector(III)Ramanathapuram –Rameshwaram-Tuticorin Sector(III)
• Sector comprises the
famous Rameswaram
island and
Dhanushkodi
• Coastal stretch of
Mandapam and
Tuticorin stetching for
about 85 Km

Ramanathapuram –Rameshwaram-Tuticorin Sector(III)Ramanathapuram –Rameshwaram-Tuticorin Sector(III)
• The cuspate foreland of
Vaigai between Uchipuli
and Mandapam and the
Rameswaram island lying
further east, separated by
the sea over a distance of
2 Km, forms the divide
between the Palk Bay in
the north and Gulf of
Mannar in the south.

Ramanathapuram –Rameshwaram-Tuticorin Sector (III)Ramanathapuram –Rameshwaram-Tuticorin Sector (III)
• Coastline exhibits
discontinuously
calcareous sandstone
and shell limestone of
Quaternary period and
occurs as abrasion
platforms.
• Shoreline covered mostly
by beach sand and
oxidized ‘teri’ sand.

IMPACT
• Coastal erosion
• Variations in soil and water characteristics
• Significant impacts are the widening of river
mouths in Gundar, Vembar and Vaippar rivers
and backflow of seawater into the river and tidal
inlets
• Deposition of sand and clay inside lagoon and
lakes
• No major effect to recent sand dune complex
• Tip of Dhanushkodi shows erosion along the
coast

Disaster Rating
• Considering the marginal impact of tsunami waves, the
sector may be categorised under less damaged
zone(Safe)
• Except for some low lying belts lying near the coast,
north and south of Tuticorin town, besides the industrial
belt located to the south of Tuticorin.

• A total of 21 small
islands, with coral
reef scattered in this
part of the sea
• Acted as natural
speed breakers to
diminish the energy
flux of the waves.

Tuticorin-Tiruchendur Sector (IV)Tuticorin-Tiruchendur Sector (IV)
• Sector falls within the Gulf of
Mannar and extends for about 35
km along NNE-SSW and N-S
directions.
• Major coastal landforms include
beach, recent dune
complex,Tambraparni estuary, etc.
• Beach is narrow with 10-15 m
width except in Tambraparni
estuarine delta, where it is
between 15 and 25 m
• Tambraparni estuarine delta, has
three major tidal inlets
• Dense Mangrove vegetations are
seen in all these channels

Impact
• No significant change in
quality of ground water
• Iimpact on mangrove
cultivations within
Tambraparni estuary and
on saltpans negligible

• Post-tsunami survey in this sector documented
the arrival time of the most destructive waves
between 13:00 and 13:30 hrs
• Run –up elevation of 1.5 to 2 m and wave
splash of 3 to 6 m
• Inundation (run-up length) between 25 and
500m
• Withdrawal of sea during the pulses of tsunami
waves was 50 –1000 m

Disaster Rating
• Considering the limited damages and natural protection
by Tambraparni estuary and its mangrove plantations
and sparse population along the coast, the sector may
be categorized under less damaged zone (Safe)
• Except for the erosional fronts of Kayalpattinam and
south bay of Tuticorin

Tiruchendur –Kanyakumari Sector (V)Tiruchendur –Kanyakumari Sector (V)
• Extends for about 85 km
• Lies in the lower segment
of Gulf of Mannar,
protruding into Indian
Ocean.
• Land forms include
beaches, recent dune
complex, wave cut
platforms; abrasian
platforms, shore
platforms by quarrying,
bay, etc.

• Withdrawal of sea
both at Tiruchendur
and Kanyakumari was
quite conspicuous.
Shoreline

• Villages of
Kulasekarapattinam
and Manappad were
protected against
major devastation by
the wave
breakers(groynes)
already erected,

• Impact on placer deposits
between Kuttam and
Ovari was not significant
except for enrichment of
Ilmenite near Vattakkottai
by the uprush of the
waves and depletion of
lighter fractions (garnet)
by the back wash

• At Kanyakumari coast
loose boulders were
tossed by the upsurge
of Tsunami waves

• Bore of tsunami
waves at
kanyakumari

Post-tsunami survey
• Recorded a run-up elevation
of waves between 1 m and 3
m
• Run-up length between 10 m
and 250 m
• Wave splash rose maximum
up to10m at Vivekananda rock
memorial, Kanyakumari
• Withdrawal of sea between the
pulses of tsunami waves
ranged from 250 to 1000m

Disaster Rating
• Considering the
damages it may be
categorised under
‘marginally high’.

Tsunami ppt

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