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Geography 🌍 > Geophysical Phenomena > Flashcards

Geophysical Phenomena Flashcards

1
Q

What is the volcano

A

A volcano is a vent or fissure at The crust from which lava that is molten rocks ash gases erupt from the magma chamber below the surface

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2
Q

What are the causes of a volcano

A

Temperature difference between inner and outer layers of the earth
the temperature difference hence conventional currents at the mantle
convection currents create convergence and Divergent boundaries which are weak zones
the Lava escape through the divergent boundary

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3
Q

Draw a diagram of the formation of the volcano

A

See notes

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4
Q

Discuss the characteristics of acidic and basic lava

A

ACIDIC = andesitic , composite , stratovolcanic

Highly viscous 
low-density high silicon
 slow flow hence the volcano steep 
rapidly solidify 
bomb and pyroclastic 
destructive boundary converging

BASIC = basaltic , shield

 Hottest highly fluid 10 to 30 mph 
dark colour due to basalt 
 high iron and magnesium low silica 
not very explosive 
gently sloping 
constructive boundary at the diverging edge
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5
Q

What are the positive effect of a volcano

A

For land forms that is the Deccan traps

Forestry at the volcano hence timber
mineral resources Kimberly Plateau diamond

geothermal electricity puga Valley in Ladakh

geysers and hot springs

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6
Q

Distinguish between geysers and hot water springs

A

Geyser is a steam or water at high-pressure which is accumulated in the fissures and fractures of the earth when the pressure exceeds threshold limit the steam burst out at the surface

Geysers have silica deposits at the mouth which give them different colours

Geysers are located near active volcanic centres

Hot water streams as steam or water at high-pressure which smoothly flows to the top through the wind and condenses at the surface
The springs are colourful due to Cyanobacteria of different colours
Found all across the earth

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7
Q

Draw a diagram of extrusive and intrusive volcanic landforms

A 
Composite volcano 
lava plateau 
ash cone 
radiating dikes 
Caldera
Laccoliths 
Sill
Dyke
Chamber
Batholith
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8
Q

What is mantle plume

A

Convection of abnormally hard rock magma within the earth surface

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9
Q

What is a hotspot

A

Mantle plume provides continuous supply of abnormally hot magma to a fixed place at mantle that is called hotspot

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10
Q

What is a super volcano

A

Volume of magma that erupts from a volcano exceeds 1000 km cube

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11
Q

Discuss the anatomy of an earthquake

A 
Fault 
epicentre 
focus hypo centre
 plates and 
seismic waves
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12
Q

What are swarms

A

Large series of earthquakes at a place for months without major earthquake

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13
Q

What are the causes of an earthquake

A

Fault zones with stress
Plate tectonics - slipping of land along faults
Volcanic activity
human induced reservoir

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14
Q

Explain the wadatti - Benioff zone with a diagram

A

See notes

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15
Q

Discuss the characteristics of primary and secondary seismic waves

A

The primary waves are
longitudinals
they travel like sound
they are the 1st to be detected
they displace medium in the same direction as they travel
they create density difference and hence they stretch and contract material
they are less destructive
they travel through solid liquid and gases

The secondary waves are 
transverse waves 
they travel like ripples 
they do not pass through liquid or gas
 they are more destructive 
they have side to side movement
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16
Q

Discuss surface waves and their types

A

Surface waves travel along the surface only
they are the most destructive
travel for longer period since longer wavelength
they are found at the epicentre

Two types
Rayleigh - up down way more damage

Love waves - fastest move from side to side

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17
Q

Discuss the shadow regions of the seismic waves

A

See diagram

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18
Q

Discuss the distribution of volcanoes and earthquakes around the world

A

The world’s greatest earthquake belt, the circum-Pacific seismic belt, is found along the rim of the Pacific Ocean, where about 81 percent of our planet’s largest earthquakes occur.
It has earned the nickname “Ring of Fire”.
The belt exists along boundaries of tectonic plates, where plates of mostly oceanic crust are sinking (or subducting) beneath another plate. Earthquakes in these subduction zones are caused by slip between plates and rupture within plates.

The Alpide earthquake belt (mid Continental belt) extends from Java to Sumatra through the Himalayas, the Mediterranean, and out into the Atlantic.
This belt accounts for about 17 percent of the world’s largest earthquakes, including some of the most destructive.

The third prominent belt follows the submerged mid-Atlantic Ridge. The ridge marks where two tectonic plates are spreading apart (a divergent plate boundary).
Most of the mid-Atlantic Ridge is deep underwater and far from human development.

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19
Q

Discuss the distribution of earthquake in India

A

See diagram

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20
Q

What are the conditions for formation of a cyclone

A

Intense low-pressure system
Coriolis force therefore air does not come straight to the low pressure source
at North hemisphere it is anticlockwise at south it is clockwise
closed isobars equal pressure

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21
Q

What is a frontal cyclones

A

It is temperate cyclone or called extra tropical
It is dynamically introduced
no role of Temperature

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22
Q

Discuss the formation of a temperate cyclone

A

Stage one
The air mass at temperate region in winter it moves away from source
warm and cold air mass come into contact and form stationary front

Stage 2
Cool and cold air mass and warm air mass start pushing each other the cold air masses push warm air upwards hence low pressure is created at the Centre
the Coriolis force acts and the air is added in circular path

Stage 3
Eventually all air of warm air mass is uplifted
cool and cold air mass is in contact and hence an occluded front is created and there are rapid changes in temperature and pressure

Stage 4
Air masses uplifted now and give rain now hot air mass is dry cool and cold air mass do not have much temperature difference and hence don’t create a front to keep cycling cycle going
When cyclone end

West to east , predictable path since slow and gradual

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23
Q

Discuss the stages of formation of a tropical cyclone

A

The tropical water is hot at late summer. Greater than 25 to 27°
Hence the evaporation is high and air rises and low-pressure zone is created

The air moves up as moisture latent heat is added

Cumulonimbus clouds are formed high-pressure at top and hence diverge

The eye is at Centre it has clear skies and high-pressure region the air descent here

See diagram

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24
Q

Distinguish between tropical and temperate cyclones

A 
Tropical cyclone has high power than temperature 
travel from east to west 
lowest pressure in the past 
and cannot be predicted 
always at a water body when at land the moisture is cut off and hence they dissipate
8 to 20 degree latitude
Small area wind greater than 120 km/h 
coastal land
Temperate cyclones are not caused by change in temperature they travel from west to east and the path can be predicted as they are gradually
Larger area 
a frontal interaction
 wind at 40 to 50 km/h 
at mainland
25
Q

What are the stages of formation of a thunderstorm

A

Land heats the air at land expands and moves up hence low pressure is created at land and air comes in at a height the air condenses water and air becomes ice and comes down as droplets therefore rain

26
Q

Why does lightning take place

A

Add the upward clouds there is ice and water which is excessively negatively charged at -5°C to -15°C the positive charge at high and low there for coming contact and charge

27
Q

What are the characteristics of a tornado

A

It is that land
there is high wind speed than tropical cyclones
the low-pressure is higher
exact mechanism is not known they survive at land and water suck up the water at the Centre

28
Q

What is polar vortex

A

It is described as a whirling cone of low pressure over the poles that is strongest in the winter months due to the increased temperature contrast
between the polar regions and the mid-
latitudes, such as the US and Europe.

29
Q

What is El Niño

A

El Nino and La Nina are complex weather patterns resulting from variations in ocean temperatures in the Equatorial Pacific Region. They are opposite phases of what is known as the El Nino-Southern Oscillation (ENSO) cycle.

El Nino is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean.
It is the “warm phase” of a larger phenomenon called the El Nino-Southern Oscillation (ENSO).

The El Nino event is not a regular cycle, they are not predictable and occur irregularly at two- to seven-year intervals.
The climatologists determined that El Nino occurs simultaneously with the Southern Oscillation.

The Southern Oscillation is a change in air pressure over the tropical Pacific Ocean.
When coastal waters become warmer in the eastern tropical Pacific (El Nino), the atmospheric pressure above the ocean decreases.

30
Q

What is the impact of El Niño

A

non-El Nino conditions in the Pacific Ocean. -

Normally, strong trade winds blow westward across the tropical Pacific, the region of the Pacific Ocean located between the Tropic of Cancer and the Tropic of Capricorn.

Impact on Ocean:
El Nino also impacts ocean temperatures, the speed and strength of ocean currents, the health of coastal fisheries, and local weather from Australia to South America and beyond.

Increased Rainfall:
Convection above warmer surface waters brings increased precipitation.
Rainfall increases drastically in South America, contributing to coastal flooding and erosion.

Diseases caused by Floods and Droughts:
Diseases thrive in communities devastated by natural hazards such as flood or drought.
El Nino-related flooding is associated with increases in cholera, dengue, and malaria in some parts of the world, while drought can lead to wildfires that create respiratory problems.

Positive impact:
It can sometimes have a positive impact too, for example, El Nino reduces the instances of hurricanes in the Atlantic.

In South America: As El Nino brings rain to South America, it brings droughts to Indonesia and Australia.
These droughts threaten the region’s water supplies, as reservoirs dry and rivers carry less water. Agriculture, which depends on water for irrigation, is also threatened.

In Western Pacific: These winds push warm surface water towards the western Pacific, where it borders Asia and Australia.
Due to the warm trade winds, the sea surface is normally about 0.5 meter higher and 4-5° F warmer in Indonesia than Ecuador.

The westward movement of warmer waters causes cooler waters to rise up towards the surface on the coasts of Ecuador, Peru, and Chile. This process is known as upwelling.
Upwelling elevates cold, nutrient-rich water to the euphotic zone, the upper layer of the ocean.

31
Q

What is La Nina

A

La Nina means The Little Girl in Spanish. It is also sometimes called El Viejo, anti-El Nino, or simply “a cold event.”

La Nina events represent periods of below-average sea surface temperatures across the east-central Equatorial Pacific.
It is indicated by sea-surface temperature decreased by more than 0.9℉ for at least five successive three-month seasons.

La Nina event is observed when the water temperature in the Eastern Pacific gets comparatively colder than normal, as a consequence of which, there is a strong high pressure over the eastern equatorial Pacific.

32
Q

What is the impact of La Nina

A

Europe: In Europe, El Nino reduces the number of autumnal hurricanes.

La Nina tends to lead to milder winters in Northern Europe (especially UK) and colder winters in southern/western Europe leading to snow in the Mediterranean region.

North America: continental North America
Stronger winds along the equatorial region, especially in the Pacific.

Favourable conditions for hurricanes in the Caribbean and central Atlantic area.

Greater instances of tornados in various states of the US.

South America: La Nina causes drought in the South American countries of Peru and Ecuador.

It usually has a positive impact on the fishing industry of western South America.

Western Pacific: In the western Pacific, La Nina increases the potential for landfall in those areas most vulnerable to their effects, and especially into continental Asia and China.
It also leads to heavy floods in Australia.
There are increased temperatures in Western Pacific, Indian Ocean and off the Somalian coast.

33
Q

What is the impact of enso cycle in India

A

El Nino: Strong El Nino events contribute to weaker monsoons and even droughts in India Southeast Asia.

La Nina: The cold air occupies a larger part of India than the El Nino cold air.
In the ‘La Nina year’, rainfall associated with the summer monsoon in Southeast Asia tends to be greater than normal, especially in northwest India and Bangladesh.

This generally benefits the Indian economy, which depends on the monsoon for agriculture and industry.

It usually brings in colder than normal winters in India.
La Nina influences the Indian subcontinent by piping in cold air from Siberia and South China, which interacts with the tropical heating to produce a north-south low-pressure system.

The cold air of La Nina associated with this north-south trough tends to extend much further south into India.
This is remarkably different from the more northwest-southeast blast of cold air associated with El Nino.

The pressure pattern going north-south means lesser impact of western disturbances.
The cold temperature can go down as far as Tamil Nadu, but may not affect the North East that much.

34
Q

What do you mean by flood

A

Inundation of land

35
Q

What are the causes of flood

A 
Heavy rains
 cloudburst
 La Nina situation 
bad drainage terai region 
, swampy  soil water logging 
basin topography Punjab and Haryana shaped like a bowl 
siltation 
landslide between the river course 
global warming glacial melting 
deforestation 
poor settlement management too close to the river
36
Q

Draw the flat map of India

A

See notes

37
Q

What are the causes of floods and what are the solutions

A

Intergovernmental panel on climate change fourth and fifth report has stated that high levels of rain at India with heat of the Tibetan pl. have called the floods

Another cause is sand mining around the river

Solution
11th plan for flood management programme
Flood control commission to control 23 rivers
Nepal and China information exchange at origin of the river
Stop silting

38
Q

What are the characteristics of the polar vortex, what causes splitting of the polar vortex

A

It spins in the stratosphere
When the vortex is the strongest cold air is less likely to plunge deep into the North America or Europe
It forms a wall and protects the mid-latitudes from the cold Artic air

When the stratosphere becomes warm the polar vortex is weakened
This split the polar vortex

39
Q

What are the effects of polar vortex splitting

A

Causes decline and extreme winter weather in the eastern United States along with northern and western Europe
It leads to the warming of the stratosphere and the troposphere
A warmer artic favour severe winter weather in the northern hemisphere mid-latitude

40
Q

What are the lightening death statistics in India

A

Caused 1771 deaths between 1 April 2019 and March 31, 2020

41
Q

What is lightning

A

It is very rapid and massive discharge of electricity in the atmosphere some of which is directed towards the earth surface

42
Q

How can lightening deaths be minimised

A

As per climate resilient observing systems promotion Council -
early lightning warnings to farmers , cattle Grazing , children and people in open areas is the key

The local lightning safety action plan like installing lightning protection devices is also need to prevent deaths

The Centre increased the compensation for victims of natural disasters to 4,00,00 in 2015
In the last five years there were 13,994 families which bring the total compensation to 359 crores

43
Q

what are space hurricanes

A

huge, funnel-like,
spiral geomagnetic storm
that occurs above the polar Ionosphere of Earth,
during extremely quiet conditions.

44
Q

what causes space hurricanes

A

result of the solar wind and Earth’s magnetic field interacting.

45
Q

discuss chinas report on the discovery of space hurricanes

A

As per their report, the hurricane measured roughly 600 miles across and rained down charged electrons for as long as eight hours.
● The space hurricane spun counterclockwise at speeds up to 4,700 miles per hour, the academic paper reported.
● The hurricane was reported in space directly above the North Pole.

46
Q

what is the significance of. the discovery of space hurricanes

A

The new finding could help scientists learn more about how the Sun affects Earth’s atmosphere, gathering more details on how space weather might harm satellites and other objects in orbit.

47
Q

what are heat waves

A

The IMD says heatwave is considered when the maximum temperature of a station touches at least 40 degrees Celsius or more for plains, 37 degrees Celsius or more for coastal regions and at least 30 degrees Celsius or more for hilly regions.

48
Q

Reasons why India is experiencing more heat waves are:

A

1 Magnified effect of paved and concrete surfaces in urban areas and a lack of tree cover.

  1. Urban heat island effects can make ambient temperatures feel 3 to 4 degrees more than what they are.
  2. More heat waves were expected as globally temperatures had risen by an average 0.8 degrees in the
    past 100 years. Night-time temperatures are rising too.
  3. Higher daily peak temperatures and longer, more intense heat waves are becomingly increasingly
    frequent globally due to climate change.
  4. High intensity of UV rays in medium-high heat wave zone.
  5. Combination of exceptional heat stress and a predominantly rural population makes India vulnerable to
    heat waves.
49
Q

How India should deal with heat waves?

A
  1. Identifying heat hot-spots through appropriate tracking of meteorological data and
    promoting timely development and implementation of local Heat Action Plans with strategic inter-agency co-ordination, and a response which targets the most vulnerable groups.
  2. Review of existing occupational health standards, labour laws and sectoral regulations for worker safety in relation to climatic conditions.
  3. Policy intervention and coordination across three sectors health, water and power is necessary.
  4. Promotion of traditional adaptation practices, such as staying indoors and wearing comfortable clothes.
  5. Popularisation of simple design features such as shaded windows, underground water storage tanks and insulating housing materials.
  6. Advance implementation of local Heat Action Plans, plus effective inter-agency coordination is a vital response which the government can deploy in order to protect vulnerable groups.
50
Q

what are impacts of heat waves in india

A

Rapid rises in heat gain due to exposure to hotter than average conditions compromises the body’s ability to regulate temperature and can result in a cascade of illnesses, including heat cramps, heat exhaustion, heatstroke, and hyperthermia.
Deaths and hospitalizations from heat can occur extremely rapidly (same day), or have a lagged effect (several days later) and result in accelerating death or illness in the already frail, particularly observed in the first days of heatwaves. Even small differences from seasonal average temperatures are associated with increased illness and death. Temperature extremes can also worsen chronic conditions, including cardiovascular, respiratory, and cerebrovascular disease and diabetes-related conditions.
Heat also has important indirect health effects. Heat conditions can alter human behavior, the transmission of diseases, health service delivery, air quality, and critical social infrastructure such as energy, transport, and water.

51
Q

what is lineament

A

linear feature in a landscape dictated by an underlying geological structure such as a fault.

52
Q

why are earthquakes frequent in Assam

A

According to the Geological Survey of India (GSI), Sonitpur district lies within a tectonically complex triangular area bounded by the east-west trending Atherkhet Fault, the northwest-southeast trending Kopili Fault and a north-south trending lineament.

53
Q

why is the northeast vulnerable to earthquakes

A

The Siang Fracture, Yemla Fault, Namula Thrust and Canyon Thrust are spread across the northeast and are active along with Main Himalayan Thrust, Main Boundary Thrust, Main Central Thrust and several subsidiary faults.
2. The northeast is demarcated as Seismic Zone V, which indicates a zone with high vulnerability.
3. The Indian plate is moving northeast toward the Eurasian plate in the Himalayan region, their oblique
collision and release of stress and strain accumulated in the local tectonic or fault environments lead to earthquakes.

54
Q

How was the cyclone taunted named

A

The World Meteorological Organisation (WMO) maintains rotating lists of names.
The word Tauktae has been suggested by Myanmar, which means ‘gecko’, a distinctively vocal lizard, in the Burmese language.
● The name is the fourth from a new list of 169 names released by the IMD last year.

55
Q

How are cyclones named

A

A WMO/ESCAP (World Meteorological Organisation/United Nations Economic and Social Commission for Asia and the Pacific) Panel on Tropical Cyclones agreed in principle to assign names to the tropical cyclones in the Bay of Bengal and the Arabian Sea during its 27th session held in Muscat, Sultanate of Oman, in 2000.
● The naming of the tropical cyclones over the north Indian Ocean commenced from September 2004, with names provided by eight members, starting with Bangladesh, followed by India. Since then, another five countries have joined the Panel.
● The Regional Specialised Meteorological Centre (RSMC), New Delhi is responsible for naming the cyclonic storms formed over the Bay of Bengal and the Arabian Sea when they reach the relevant intensity

56
Q

What causes cyclones to spin

A

Wind always blows from high pressure to low pressure areas. High pressure areas are created in the cold region while low is created in the warm regions. Polar regions are high pressure areas as the amount of sunlight here is less than the tropical region. So, wind blows from polar regions to tropical regions.
● Then comes the Earth’s movement, which is west to east. The Earth’s rotation on its axis causes deflection of the wind (in the tropical region as the speed of spinning of Earth is higher compared to polar sides due to its spherical shape — blowing from both the polar regions. Wind coming from the Arctic is deflected to the right while Antarctic wind deflects to the left side.
● So, wind is already blowing in a direction. But when it reaches the warmer place, cool air starts getting attracted to the centre to fill the gap. So while moving to the centre, cool air keeps getting deflected resulting in circulation of wind movement — this process continues until the cyclone hits the land.

57
Q

Why are cyclones concentrated in the Bay of Bengal area

A
  1. The vast low pressure created by the warm water of the ocean.
  2. The Bay of Bengal shaped like a trough that makes it more hospitable for storms to gain force.
  3. The high sea surface temperature makes matters more worse in the Bay triggering the intensity of the
    storms.
  4. The Bay of Bengal also gets more rainfall with sluggish winds
    and warm air currents around it that keep temperatures
    relatively high all year.
  5. The constant inflow of fresh warm water from the perineal
    rivers like Bramhaputra, Ganga makes it further impossible to
    mix with the cooler water below.
  6. Lack of landmass between the Pacific Ocean and the Bay of
    Bengal tend cyclonic winds to move into the coastal areas
    causing heavy rainfall.
  7. The absence of air movements from north-western India
    towards the Bay in the post-monsoon phase is also another reason for the chances of cyclones in the Bay of Bengal.
58
Q

What geographical advantage does Arabian Sea have regarding cyclones

A

● It is much calm as the stronger winds help dissipate the heat.
● Lack of constant fresh water helps the warm water to mix with the cool water underneath, reducing
the surface temperature.
● The Arabian Sea enjoys the locational advantage as the winds from the Pacific Ocean encounter the
Western Ghats and the Himalayas cutting down on its intensity and sometimes never reaching the Arabian Sea.

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