6.1 Earthquakes and volcanoes (impacts and stra) Flashcards
describe the structure of the Earth
crust,
mantle
(inner & outer) core
crust
The outer layer of the Earth made up of solidified rocky plates.
Mantle
The layer of molten rock on which the crust floats
core
Outer core
made of very hot molten metal.
Inner core
made of solid metal
Types of crust
1- The oceanic crust
2- Continental crust
The oceanic crust (sial) features
➢ Very dense
➢ Younger
➢ Can sink and is constantly being destroyed and replaced
2- Continental crust
➢ Light weight
➢ Old
➢ Cannot sink and cannot be destroyed
Plate boundaries
where two or more plates meet.
3 types of plate boundaries
constructive,
destructive
conservative
Constructive/Divergent plate boundary
- when there are two plates moving apart from each other.
- They are called constructive plates because when they move apart a gap is created, magma rises up in the gap and forms lava and solidifies- this forms volcanoes.
Destructive/convergent plate boundary
- This occurs when oceanic and continental plates move towards each other.
- The oceanic plate is forced under the lighter continental plate as it is denser.
- Forming a sebduction zone.
- Friction causes melting of the oceanic plate converting it to magma and may trigger earthquakes.
- Magma rises up through cracks and erupts due to pressure onto the surface and forms a destructive volcano
Conservative/ transform plate boundary:
- Plates slide past each other in opposite directions, and gets stuck
- Friction takes place between the plates and pressure builds up,pressure is releases as plate move suddenly;
- This creats a seismic wave through the crust from the focus leading to earthquake
What are Volcanoes
An opening in the earths crust through which magma from eithin the mantle is erupted onto the land
Causes of valcanoes
Constructive plate boundary
Destructive plagte boundary
Shield volcanoes
➢ Found on constructive plate boundaries
➢ low height and wider base
➢ gentle slope
Composite volcanoes
- Found on a destructive plate boundary
- high height shorter base
- steep slope
Distribution of volcano and earthquake
Both:
* Encircle the whole of the pacific ocean (ring of fire)
* Extend down the entire length of the mid-atlantic ocean
Earthquake-
* stretch across the southern Europe and Asia
Valcanoes-
* some in southern Europe, the Caribbean and east africa
Earthquakes
The shaking and vibration of the Earth’s crust due to movement of the earth’s plates (plate tectonics)
Causes of Earthquakes
Conservative plate boundary
sometimes destructive
How are earthquakes measured?
The Richter Scale measures the magnitude of a tremor (how powerful it is) using an **instrument called a seismometer **
Impacts of tectonic events (volcanoes and earthquakes)
- damage to buildings and infrastructure,
- fire,
- tsunamis,
- landslides,
- loss of farmland and habitats, leading to starvation
- water-related disease,
- loss of life,
- trauma,
- financial losses
Managing the impacts of tectonic events (earthquakes and volcanoes)
- monitoring and warning,
- land use zoning (not building on areas prone to hazard)
- structure of buildings (earthquake proof)
- disaster preparation (plans, drills, emergency supplies and emergency rescue teams),
- evacuation plans
- rebuilding of damaged areas,
- international aid
- food storage
- hazard zone map
Opportunities presented by valconoes
- Tourist attraction
- provide income and employment
- fertile soils,
- Exraction of minerals,
- heat generated provide good source for geothermal energy resources
why do more people die AFTER
earthquakes
● lack of medical help
● lack of clean water
● outbreak of water related diseases
● lack of food
● crime
● lack of shelter
● risk of aftershocks
why do people continue to live in region with natural hazards
● nowhere else to move
● familial ties
● lack of money
● no employment
● Confidence in prediction, preparation and protection.
