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Geography > 2. Tectonic Hazards > Flashcards

2. Tectonic Hazards Flashcards

1
Q

What is the structure of the earth?

A
  • Inner core (1400km in diameter) - solid made of iron and nickel at 5500 degrees
  • Outer Core - 2100 km thick, semi-solid , temp around 5250
  • Mantle - 2900 km thick, semi molten, less dense than the outer core
  • Crust - oceanic and continental 2 types
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1
Q

What are the 2 types of crusts?

A
  • oceanic crust - thinner (5-10km) but is more dense and heavier
  • continetal crust (older than oceanic as does not subduct) - 25-90 km, thicker but lighter and less dense
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2
Q

What is the slab-pull theory?

A
  • the movement of plates is due to the subduction of oceanic plates into the mantle and dragging the rest of the plate with it
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3
Q

Where do earthquakes occur?

A
  • on all plate boundaries
  • mainly around the pacific ring of fire
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4
Q

Where do volcanoes form?

A
  • at constructive or destructive margins
  • can also form at hotspots (where columns of magma escape through the crust of the earth)
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5
Q

What takes place at a constructive plate boundary and what is an example?

A
  • at a constructive plate boundary the plates move apart
  • e.g Mid Atlantic Ridge
  • make broad and flat shield volcanos
  • as magma break through overlying crust shockwaves create earthquakes
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6
Q

What happens at a destructive plate boundary and what is an example?
(continental and oceanic)

A
  • at a destructive plate boundary plates collide into each other
  • when oceanic (Nazca) and continental collide (South American) collide, the oceanic subducts under the continental as it is more dense
  • friction causes earthquakes and the melting of the oceanic plate makes magma which breaks through to make a steep sided composite volcano (violent and explosive)
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7
Q

What happens at a destructive plate boundary (continental and continetal)

A
  • there is no subduction inside 2 plates collide and crust becomes crumpled and uplifts
  • causes fold mountains such as Himalayas and formations of mountains cause earthquakes
  • no volcanos
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8
Q

What takes place at a conservative plate boundary and what is an example?

A
  • 2 plates move past each other in opposite directions or the same direction but at diff speeds
  • only earthquakes take place due to the friction
  • no volcanos
  • San Andreas Fault
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9
Q

What are primary hazards of volcanic eruptions?

A
  • ash
  • pyroclastic flow (superheated material travels up to 500 km/h)
  • lava flow
  • gas emissions (sulfur dioxide, CO2 and water)
  • volcanic bombs (rocks ejected by volcano)
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10
Q

What are secondary hazards of volcanic eruptions?

A
  • Lahars (water mixes with ash to create fast mudflow)
  • Acidification (sulphur mixes with water to increase acidity of water)
  • Landslides
  • Climate Change
  • Fires
  • Floods
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11
Q

What are primary effects of earthquakes?

A
  • ground shaking
  • gas emissions
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12
Q

What are secondary effects of earthquakes?

A
  • building collapse
  • landslides
  • gas leaks
  • fires
  • soil liquefaction
  • subsidence (shrinking of the earths surface)
  • mudflows
  • tsunami
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13
Q

What is some general infomation about Nepal?

A
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14
Q

What are primary effects of earthquakes?

A
  • caused by the ground shaking, can include death injuries and damage to roads and buildings
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15
Q

What are secondary effects of earthquakes?

A
  • These are the effects that are the results of primary effects such as tsunamis, fires and landslides
16
Q

Ranking of GDP for Chile and Nepal?

A
  • Chile, 38/193
  • Nepal, 109/193
17
Q

HDI Ranking for Chile and Nepal?

A
  • Chile, 41/187
  • Nepal, 145/187
18
Q

Plate Boundary and Magnitude of Chile Earthquake?

A
  • Nazca and South American Plate
  • Destructive Plate Margin
  • 8.8 on Richter Scale
19
Q

Plate Boundary and Magnitude of Nepal Earthquake?

A
  • 7.9 on Richter Scale
  • 80Km from Capital Kathmandu
  • Destructive Plate Margin
  • Indo-Australian plate collides with Eurasian
  • Shallow Earthquake, 15km below ground
20
Q

Chile Primary Effects (5)

A
  • 500 killed
  • 12,000 injured
  • 800,000 affected
  • Port and Santiago Airport badly damaged
  • Cost of earthquake is US$30Billion
21
Q

Chile Secondary Effects

A
  • 1500km of road destroyed
  • Coastal Towns devastated by Tsunami waves
  • Fire at chemical plant near Santiago
22
Q

Nepal Primary Effects (6)

A
  • 9000 people died
  • 8 million affected (1/3 pop. Of Nepal affected)
  • 3 Million left homeless (1/8)
  • 7000 schools destroyed
  • 50% of shops destroyed
  • Damage over $5 Billion
23
Q

Secondary Effects in Nepal

A
  • Triggered landslides and avalanches
  • Avalanches on Mount Everest killed 19 people
  • Another Avalanche in Langtang left 250 people missing
  • Landslide blocked Kalli Gandaki River
24
Q

What are the 2 types of responses to earthquakes?

A
  • Immediate Responses - directly after the event
  • Long Term responses - Re-building and reconstruction with aim of returning back to normal
25
Q

Chile Immediate Responses?

A
  • Emergency Services acted quickly.
    – international help was needed by field hospitals, satellite phones and bridges
  • Temporary repairs were made to the Route 5 highway which enables aid to be transported rapidly
  • Power and Water restored within 10 days
  • National Appeal raise $60 Million
26
Q

Chile Long Term Responses

A
  • 1 Month after the earthquake, Chile’s government launched a housing reconstruction plan to help 200,000 homes destroyed in the earthquake
  • Chile has a strong economy mainly based on copper exports that could be rebuilt without much foreign aid
  • President announced Chile would be fully recovered in 4 years
27
Q

Nepal Immediate Responses?

A
  • Search and Rescue and Medical Support quickly arrived from countries such as India
  • Helicopters delivered supplies to cut off villages and helped those trapped in avalanches
  • Half a million tents provided
  • Field Hospitals set up to avoid overcrowding
  • Many countries pledged financial aid
  • 300,00 people migrated away from Kathmandu to friends + family
28
Q

Nepal Long Term Responses?

A
  • Roads repaired and landslides cleared
  • Stricter building codes
  • Tourism was boosted in July 2015 by major heritage sites being reopened
  • 7000 schools to be re-built
29
Q

What are some reasons why people live in areas at risk?

A
  • fertile soils near volcanos due to minerals so crop yield are higher here
  • tourism, people want to visit these areas so jobs are more readily available
  • minerals and precious stones can be mined in these areas
  • areas can be used to produce geothermal energy
  • people in poverty may have pressing issues
  • social reasons such as family land
30
Q

What are the 4 management strategies to reduce risk of tectonic hazards?

A
  • monitoring
  • prediction
  • planning
  • protection
31
Q

How can tectonic hazards be monitored?

A
  • volcanos can be monitored using:
    1. Seisometers (detect tremors)
    2. remote sensing (satellites detect heat increases inside volcanos)
    3. gas sensors (detect increases in gases such as sulphur and radon that are released before eruption)
  • earthquakes can be monitored using:
    1. Seisometers (detect foreshocks)
    2. gas sensnors (apparently radon released before earthquake)
32
Q

How can tectonic hazards be predicted?

A
  • volcano monitoring allows accurate predictions of eruptions so evacuation and exclusion areas can be put in place
  • earthquakes are impossible to predict at all
33
Q

How can tectonic hazards be protected against?

A
  • VOLCANO around volcanos exclusion and evacuation zones can be set up
  • stregnthening of roofs to support falling ash weight
  • EARTHQUAKES: earthquake drills
  • earthquake resistant building design such as shutters on the windows
  • sea walls to protect against Tsnunami
34
Q

How can tectonic hazards be planned for?

A
  • (both volcanos and earthquakes)
  • hazard mapping and risk assesments to identify those most at risk (so people can be moved and building stopped)
  • evacuation plans and stockpiles can be made
  • emergency services can be trained

Geography (19 decks)

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