2.1 Earth quakes and volcanoes Flashcards
Earthquakes:
- A series of vibrations or movements in the earth’s crust
- Caused when two plates ‘stick’; pressure builds up; one
plate jerks forward sending shock waves to the surface
Features of Earthquakes:
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- Focus: point of earthquake
- Epicenter: point directly above the focus, on the
ground - Seismic waves
- Shaking ground
- Subduction zone: occurs at destructive margin, one
plate goes under the other
Effects of Earthquakes:
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- Large number of deaths
- Fires breaking out
- Water pipes burst
- Water contamination, diseases
- Corpses: human & animal
- Accessibility difficult
- Building damaged/destroyed
- Tsunami can follow
- Reconstruction costs
How to predict an Earthquake:
- Measure earth tremors, pressure, and release of gas
- Use maps and facts to find pattern in time/location
- Unusual animal behaviour
Peperations for an Earthquake:
- Build earthquake-proof buildings and roads
- Train emergency services
- Set up warning system
- Create evacuation plan
- Emergency food supply
- Practice drills
Earthquake Proof buildings
- Automated weights on roof to reduce movement
- Fire-resistant building material
- No bricks or reinforced concrete block
- Rubber shock-absorbers between foundations
- Foundation sunk deep into bedrock avoiding clay
- Roads to provide access by ambulances & fire engines
- Open areas where people can assemble if evacuated
- Automatic shutters come down over the windows
- Interlocking steel frames which can sway during earth
movements
Volcanoes:
A vent in the earth’s surface where magma, gas or ash
escapes onto the earth’s surface or into the atmosphere.
Causes for volcanoes:
- At constructive margin: plates move away from each
other; magma rises to fill the gap; - At destructive margin: oceanic crust melts from
friction and heat from mantle; newly formed magma
is lighter so it rises to surface
Volcanic plug:
lava shoots up, falls into vent & solidifies
What are volcano layers made of
Ash, dust, rock and cooled lava
Different types of volcanoes (3 types)
- Active
- Dormant
- Extinct
Active volcanoes:
has erupted recently
Dormant volcanoes:
has not erupted recently but may in future
Extinct volcanoes:
unlikely to ever erupt again; no magma inside
Volcano appearences
Shield, Cone, Composite
Shield volcanoes:
Gentle slopes, slow flowing lava
Cone volcanoes:
Steep slopes, violent eruption
Composite volcanoes
Mix of cone and shield, eruption varies in strength, made of layers of ash and lava (unstable)
Volcano characteristics:
- Large Crater
- Lava vent
- Side vent
- Magma chamber
Volcano hazards:
- Plume (ash cloud)
- Pyroclastic flow (most deadly hazard)
- Lava flow (lava is magma but when it is out of the
volcano it is called lava) - Lahars (violent type of mudflow or debris flow
composed of a slurry of pyroclastic material, rocky
debris and water) - Landslides
- Dust, ash, steam, gas
- Volcanic bombs (rocks)
Advantages of Volcano:
Tourist attraction:
- income and employment
Creates fertile soil:
- good agricultural land to grow crops
Geothermal heating:
- Renewable resource
- Heating (hot water)
- Geyser & mud baths
Disadvantages of Volcano:
- Destruction of land, property, jobs, homes, transport
- Rebuilding costs
- Unemployment
- Fires breakout
- Diseases from poor sanitation
- Gas from eruption suffocates
- Pyroclastic flow
Prediction for Volcano:
- Tremors within volcano
- Ground temps. rise
- Volcano swells & bulges
- Emits gas & steam
- Animal behaviour changes
Preperation for Volcano:
- Set up warning system
- Create evacuation plan
- Train emergency services
- Organize post-eruption plan
- Emergency food supply
