Hazardous environments Flashcards
(21 cards)
What happens at a destructive margin?
- Oceanic plate subducts under continental plate
- Ocean trench, composite cone volcano and earthquakes occur
- Volcano - magma rises through cracks in the crust and pressure builds up until an eruption
What happens at a conservative margin?
- Plates move past each other at different speeds
- Pressure builds up as they snag on each other
- EQ eventually occur as plates jolt
What happens at a constructive margin?
- Plates move away from each other
- Magma pushes through plate gaps
- Shield volcano formed
What happens at a collision margin?
- Two continental plates move towards each other
- Fold mountains form as they are equally dense
Density of oceanic plate
3g/cm^3
Density of continental plate
2.7g/cm^3
How do plates move
Convection currents in the asthenosphere
How do hotspots form?
- Weakness in the crust (thinner) above a large magma plume
- Magma breaks through cracks to create shield volcanoes
- Plates move and volcanoes form in different areas as magma plume doesn’t move
Main features of composite volcanoes (opposite for shield)
- High viscosity lava
- Steep relief
- Explosive eruptions
- Have pyroclastic flows, lava bombs and ash clouds
2 dangers of volcanic eruptions
Volcanic bombs and pyroclastic flows
2 reasons people live near volcanoes
Family ties and fertile land
Difference between the focus and epicentre of an earthquake
Focus - where the EQ is from
Epicentre - point on surface directly above EQ
What is used to measure earthquakes
Moment Magnitude Scale
How to prepare for an earthquake
- Earthquake drills
- Pack emergency kits
- Have EQ proof building codes (expensive and corruption…)
What is hazard mapping?
Maps which show the public which areas are at greater risk to natural hazards
Conditions for tropical storms
- Warm sea temperature
- High humidity
- Latitude - 5-20 degrees N/S
How do tropical storms form
- Moist air rises and cools to form cumulonimbus clouds
- Low pressure at the bottom so winds rush in
- Highest pressure in the eye
What scale is used to measure tropical storms
Saffir-Simpson Scale
Explain the Coriolis effect
Clouds that form at the equator are blown North/South and deflected to the right. They move very quickly due to the law of inertia and move faster than the land underneath it
What is pancaking
When a floor of a building collapses causing the rest of the building to collapse in on itself
Why are storm surges dangerous
They flood low lying coastal areas destroying buildings
