hazards from consolidation mindmap Flashcards
hazard defintion
Threat of significant loss of life, severe impact on life, or property
damage caused by an event – must put people at risk to be a hazard.
disaster definition
When a hazard leads to widespread destruction.
geophysical hazard
Driven by Earth’s internal forces,
e.g. earthquakes, volcanoes, tsunamis.
atmospheric hazard
Resulting from weather
processes, e.g. tropical storms, wildfires.
hydrological hazard
Linked to water bodies, e.g. floods, droughts.
primary effects
Happen immediately – caused by ground shaking
or extreme winds, e.g. homes collapse, damage to infrastructure, etc.
secondary effects
The after-effects that are a result of the primary impacts,
e.g. disease outbreaks, water/power supplies cut off, economic downturns, etc.
perception of hazards
- Population growth forces settlement in high-risk areas
- Some accept risks, such as farming on fertile volcanic soil
- Natural disasters also have major economic effects, with
wealthier nations recovering faster than poorer ones - Many underestimate risk; Kates (1971) found storm survivors often did not
expect repeat damage - Factors like age, status, and beliefs influence evacuation decisions
key approaches to hazard response
- Fatalism – accepting hazards as uncontrollable
- Prediction – improved technology aids early warnings
- Adaptation – adjusting behaviour to minimize losses, often cost-effective
key stages of the hazard management cycle
Preparedness: Education and planning reduce damage and
speed recovery.
Response: Speed depends on emergency plans.
Recovery: Restoring normal life.
Mitigation: Reducing hazard severity and impact.
three main stages of the park model of disaster response
1) Relief: Immediate aid and
rescue efforts.
2) Rehabilitation: Restoring
temporary infrastructure.
3) Reconstruction: Returning
to pre-event conditions or
improving resilience.
This model helps communities and governments plan for and manage disaster
recovery effectively.
the core-
what is the inner and outer cores made from
The core is the hottest part of Earth, composed of iron and
nickel, four times denser than the crust. It has:
Inner core: Solid iron-nickel alloy (4 times denser than the crust).
Outer core: Semi-liquid iron and nickel, generating Earth’s
magnetic field.
the mantle- lithosphere and athenosphere
The mantle is the largest layer (2,900 km thick) with semi-molten
silicate rocks – makes up the bulk of the planet and is solid,
increasing with density with depth.
Lithosphere: Includes the crust and upper mantle, forming
tectonic plates.
Asthenosphere: Softer layer (almost plastic-like) – can move very
slowly due to the high temperatures.
continental drift and alfred wegener
Developed in 1912 by Alfred Wegener – noticed
that the South American east coast and African
west coast fitted together like a jigsaw. Suggested
that all continents were part of a supercontinent
(Pangaea) – and had been drifting apart for millions of years.
But a lack of evidence meant his ideas were dismissed until after his death.
sea floor spreading
At divergent plate boundaries and mid-ocean ridges
magma rises to the surface creating new crust – spreading the sea-floor.
Palaeomagnetism:
Later confirmed symmetrical magnetic field reversals,
confirming sea-floor spreading.
the crust - overview, continental, and oceanic
Thinnest layer – varies in thickness from 5–10 km under oceans
to 70 km under continents. It has two types:
Oceanic crust (sima): Basaltic rock, rich in silica and magnesium.
Constantly renewed when subducting – so newer.
Continental crust (sial): Granitic rock, rich in silica and aluminium.
Sial is thicker but less dense than sima – so is older
mantle convection
Heat from the earth’s core rises within the mantle to drive convection
currents. For many years this was accepted as what caused plate movement, but most scientists
now reject this theory, in favour of ridge push and slab pull…
ridge push
Cool oceanic lithosphere is denser and gradually
subsides into the mantle below it; resulting in a slight incline
with distance from the ridge. Gravity makes the rigid
lithospheric plates slide down the hot, raised asthenosphere
below mid-ocean ridges. Also called ‘gravitational sliding’.
slab pull
Coolest and densest section of a tectonic plate
(furthest from the ridge) produces a downward force along
the rest of the plate, subducts into the mantle at destructive
plate margins. Thought to be the most important mechanism
for plate movement.
Divergent Margins
When plates separate, they form constructive
margins – new crust is formed when magma
(caused by the upper mantle melting) rises to
the surface and fills the gap created by the
plates moving apart.
what do divergent margins create
mid ocean ridges, rift valleys, mid ocean ridges, rift valleys
mid ocean ridges
These submarine mountain
chains, cut by transform faults, extend for thousands of kilometres. Rising magma solidifies into new crust, sometimes forming volcanic islands
rift valleys
Continental divergence fractures
the lithosphere, causing land to collapse between faults while horsts remain elevated.
