Natural Catastrophic events

volcanism

earthquake

Tsunami

complete sequence of processes of creation and movement of magma + creation of volcanic landforms

Volcanism is not randomReason associated with volcanism is also not random

Volcanism

Geomorpho

•1st

•Pacific Ring of Fire•O-O convergence•O-C convergence

Distribution of Volcanism

O-O : Volcanic arc O-C :Volcanic mountains

Plate movements

2nd •O-O divergence•Basaltic – peaceful eruption

Mid Oceanic Ridge

3th •Breaking up of Mediterranean plates into multiple blocks•Andesitic eruption•Frequent interaction•Mt. Etna, Mt. Vesuvius

Mediterranean volcanism

•Mediterranean sea is residual part of Tethys sea•Tethys sea was located between – Laurasia and Gondwana•Collision of Africa to Laurasia – breaking up of plates of Mediterranean sea

History of Mediterranean sea

•4th •Magma From deep interior -Basaltic•Fixed place - Plate movement – Island arc•Direction of plate•Hawaii, Reunion, Kurile, Aleutian

Hot Spot Volcanoes

Aleutian Islands

Basaltic eruption

Occur at mid-oceanic ridge and hot spot volcanism

Basalt highly fluid – mobile

Spread across easily

Quite eruption

Volcanic arcs, volcanic mountains

Andesite – less fluid – less mobile

Solidifies at short distance- intense pressure develop inside –explosive

Andesitic eruption

comparison

Basaltic eruption Andesitic eruption

comparison

Landforms

Extrusive

Volcanic plateau

Volcanic cones

Intrusive Dykes etc.

Volcanic Landforms

Intrusive Landforms

Intrusive LandformsIntrusion of Magma in sedimentary rocksSills (Horizontal)Dyke (Vertical)Laccolith – magma which could not come out

Lopolith – saucer-shapedPhacolith – shape like waves Batholith – intrusive granitic rock

Intrusive Volcanic Landforms

Extrusive

Volcanic Plateau

Volcanic cones

Shield volcano

Cinder vol.

Composite vol.

Extrusive volcanic Landforms

•Hot spot volcano on continental crust•Cracks on continental crust –Basaltic eruption•Spread across the land •Layer over layer•EX. Deccan lava trapps

Lava plateaus

• Indian plate passed over a hot spot near Reunion Island•Basaltic eruption•Layer over layers – looks like steps => Deccan lava traps•Soil – black soil ‘regur’

Indian Deccan trap

Spatial distribution of Lava Plateau

•Columbia-snake plateau, USA•Ozark plateau, USA•Parana-Patagonia, S. America•Adamawa plateau, Africa•Bie plateau, Africa•Katanga Plateau, Africa

Deccan plateau, India•Arabian plateau•Balkan plateau, Europe•Siberian plateau, Russia•Yunan Plateau, China•Shan plateau, Myanmar•Kimberly plateau, Australia

List of lava plateaus of the world

Extrusive

Volcanic Plateau

Volcanic cones

Shield volcano

Cinder vol.

Composite vol.

Extrusive volcanic Landforms

•Volcanic Islands (Hot spot)•Highly fluid lava (basaltic) build dome •Gentle slope•Quite volcano•Volcanoes of Hawaii

Shield / Dome volcano

•O-C collision – volcanic mountains•Less fluid lava (Andesitic) explode violently•Viscous lava solidifies at short distance

•Mt. Paricutin, Mexico

Cinder cones

Volcanic mountainsEach new eruption – new layers of ash or lava

Mt. Stromboli, Mt. Vesuvius, Mt. Fuji

Composite Cones

Shield/ dome Cinder Composite

Highly fluid Less fluid / highly viscous

Fluid + viscous

Silent flow Violent eruption Multiple and violent eruption

Gentle slope Steep slope Highest volcanoes

Small volcanoes Small volcanoes Large volcanoes

Types of Volcanic cones

•Geysers =fountains of Hot water•Ground water heated by shallow source of magma•Old faithful geyser, Yellow stone park, USA

Geysers

•Hot Spring: •Water reach deep enough – heated by interior •Locate any part of the world

Hot Spring

•Geyser – G/w heated by shallow magma source•Hot spring – g/w heated by either magma source or heated rocks•Geyser – chamber in interior – pressure – comes out like fountain•Hot –spring - quite

Difference between geyser and Hotspring

geyser

Geysers are rareHot water dissolved with silica accumulated on surface – gives different colours

USA, - Yellowstone park

Found anywhereThey gets different colors from heat-loving bacteria, like cyanobacteria

Medicinal valuesCan be helpful in harness geo-thermal energy

Hot spring

comparison

•Heated water is taken out – used for moving turbine – generation of electricity•Cooled water flown back into interior

Geo-thermal energy

Difficult to locate a good source of geothermal reservoir with current technology

Difficult to dig a deep well with hard and hot bedrock

Harmful gases can escape from the earth interior while exploration – GHG gases and dissolved toxic elements

Limitations of geo-thermal energy

volcanism

earthquake

Tsunami

Sudden movement or vibration in earth’s crust.

Release of the energy due to intense pressure + active internal dynamism of the earth

Earthquake

Geomorpho

1) Shallow focus EQ2) Intermediate focus EQ3) Deep focus EQ

Shallow focus – destructive

Types of Earthquake

At Junction of 3 plates

Subduction of Pacific plate

Earthquakes in Japan

1st Collision of Plate boundariesO-O collisionO-C collisionC-C collision

Reasons behind EQ

2nd

Divergent Plate boundaries

O-O divergence MOR

Reasons behind EQ

•3th•Transverse plate boundaries•Friction developed between two plates

Reasons behind EQ

4th Mediterranean sea regionNumerous small platesFrequent interactions

Reasons behind EQ

5th Craton = stable part of crustRe-emergence of old fractures

6th Human Induced 1) RIS2) mining3) Nuclear testing

Reasons behind EQ

Catastrophic events on earthTheir reasons and distributionsVolcanismEQ

GeomorphologyOceanography

volcanism

earthquake

Tsunami

Submarine EQSudden disturbances of underlying plates transmit the shock waves to surface waves

Tsunami

Geomorpho

Normal waves

Speed – 100 kmphCover shorter distancesWavelength ~100 km

Speed – 700 kmphCover longer distances

Wavelength – > 150 km

Tsunami waves

comparison

•Distance between two crests of troughs = wavelength

•Waves of Tsunami are wider than normal waves of the ocean water

wavelength

•EQ on ocean crust – uplift the water upward•Tsunami wave generated•Sea water recede at the shore•Vessels in the mid-sea cannot recongnise the tsunami waves

Phase 1

•At coast – depth decrease – wavelength decreases – wave height increases•A huge wall of water – 10-12 floor high created•Enormous energy released at the shore

Phase 2

•Hit the coast• Tsunami- not a single wave but multiple waves •4th and 8th waves are the most dangerous•Time lapse between each waves – 15 to 50 minutes

Phase 3

Phases of tsunami

Tsunami Early warning system- gives warning in 10 minutes of submarine earthquake

Indian National centre for Ocean Information Sciences (INCOIS),Hyderabad

To capture Tsunami wave amplitude on 24x7 basis

real time sea-level sensors with bottom pressure recorders

HF radars for coastal currentsCoastal tide gauge stations  

Indian preparedness against Tsunami

GeomorphologyInterior of the earthContinental drift – sea floor sprading- plate tectonic theories

Mountains –plateaus –plainsCatastrophic events – Volcanism, EQ and Tsunami