geograph l4
TRANSCRIPT
• 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 rare• Hot water dissolved with
silica accumulated on surface – gives different colours
• USA, - Yellowstone park
• Found anywhere• They gets different colors
from heat-loving bacteria, like cyanobacteria
• Medicinal values• Can 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 earth
Their reasons and distributions
VolcanismEQ
Geomorphology
Oceanography
volcanism
earthquake
Tsunami
Submarine EQSudden disturbances of underlying plates transmit the shock waves to surface waves
Tsunami
Geomorpho
Normal wavesSpeed – 100 kmphCover shorter distancesWavelength ~100 km
• Speed – 700 kmph• Cover 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 currents• Coastal tide gauge stations
Indian preparedness against Tsunami
GeomorphologyInterior of the earthContinental drift – sea floor sprading- plate tectonic theories
Mountains –plateaus –plains
Catastrophic events – Volcanism, EQ and Tsunami