Hazards resit Flashcards
Give give two characteristics of the crust?
It is split into two both continental and oceanic.
beneath the oceans it is only 6-10 km thick
Give two differences between the oceanic and continental crust?
The continental is older, over 1,500 million years the oceanic is less than 200 million.
The continental is heavier than oceanic.
Give two characteristics of the mantle?
The mantle is made up of semi molten roc.
It is made up of lighter element such as silicon and oxygen.
Describe the core?
The core is made of two layers, the outer core and inner core.
Outer core composed of liquid iron and nickel.
The crust is separated from the mantle by the….
Lithosphere the Moho
Define the lithosphere and asthenosphere?
The lithosphere is the rigid outer part of the earth.
The asthenosphere is the upper layer of the earths mantle.
What are two internal sources of energy?
Heat from gravity.
Nuclear decay.
What was the supercontinent called 300 million years ago?
Pangaea
What was Alfred Wegeners theory?
Continental drift.
What evidence supported wegeners theory?
The same Fossil remains of a reptile were found in both South America and Southern Africa.
The fossilised remains of a plant which existed when coal was being formed have been located only in India and Africa.
Why did some scientist reject the theory?
Because there wasn’t enough evidence to prove his theory.
What occurs at a constructive plate margin and is also know as gravitational sliding?
Slab push
What occurs at a subduction zone and is the force that the sinking edge of the plate exerts on the rest of the plate?
Slab pull
What is the scale that is used to measure the magnitude of volcanic activity?
VEI
Describe the distribution of volcanic activity?
Associated with plate tetontic processes.
Located along plate margins.
Along oceanic ridges where plates are moving apart.
On or near subduction zones
Hot spots.
Name primary effects
Tephra
Pyrocastic flows
Lava flows
Volcanic gases
Name secondary effects
Lahars Flooding Tsunamis Acid rain Climate change
Outline characteristics of a primary volcanic hazard ?
Tephra- solid material of varying grain size ranging from volcanic bombs to ash, all ejected into the atmosphere.
Name the characteristics of a secondary volcanic hazard?
Acid rain- volcanoes emit gases which include sulphur. When this combines with atmospheric moisture, acid rain results.
What is viscosity?
The state of being thick, sticky and semi fluid in consistency due to internal friction.
What 3 factors can effect viscosity?
The silica content
Dissolved gases
Temperature
Name 3 types of lava and order them from the lowest to Highest viscosity?
Balatic
Andesitic
Rhyoltic
Explain one way in which we can monitor active and dominant volcanoes?
Measure the amount of gas being produced.
Name the case study for a volcanic eruption and when did it occur?
Mt Nyriagono, Congo January 2002
give 3 pieces of background information?
The main crater of the volcano is 250 m deep.
Since the nineteenth century the volcano has erupted over 30 times.
The death toll reached 147
Give two reasons why the locals are at risk?
It’s is a fertile region so doesn’t put people off living their encouraged large number of people to live in the area.
34 eruptions since 1882 but not all involve lava flows.
