Tectonic Hazards (from revision booklet)

define natural hazard

a natural event that threatens people or damage property

name 2 types of tectonic hazards

• earthquakes

• volcanoes

explain what is meant by geomorphological hazards and give 3 types

• caused by land processes

• landslides

• mudflows

• avalanches

explain what is meant by atmospheric hazards and give 3 types

• caused by weather/climate

• tropical storms/hurricanes

• droughts

• flooding

explain what is meant by biological hazards and give 2 types

• caused by disease spreading

• pandemics

• infectious diseases (e.g. malaria)

list 6 factors affecting hazard risk

• wealth of country (HIC/LIC)

• time of event (day/night)

• magnitude of event

• climate affecting frequency

• location (relief of land/rock type/where hit)

• density/distribution (pop increase affects how many open to event)

what are the layers of the earth?

• crust

• mantle

• inner core

• outer core

give 3 ways tectonic plates can move

• convection currents

• ridge push

• slab pull

explain convection currents as a reason why tectonic plates move

• hot core causes magma to rise in mantle + sink toward core when cools

• convection builds pressure + carries plate with it

explain ridge push as a reason why tectonic plates move

• magma rises as plates move apart at constructive plate margin

• magma cools to form new plate material

• as cools, becomes dense + slides down away from ridge

• causes tectonic plates move away from each other

explain slab pull as a reason why tectonic plates move (cat gif)

• at destructive plate margin denser plate sinks into mantle due to gravity

• + pulls rest of plate along behind it

what are the characteristics of continental crust?

• less dense

• doesn’t sink

• older

• thick

• can’t be destroyed

what are the characteristics of oceanic crust?

• more dense

• sink in mantle when continental + oceanic meet

• younger

• thin

• destroyed at destructive plate margin

describe the global distribution of earthquakes + volcanoes and their relationship to plate margins

• generally earthquake origins on tectonic plate boundaries

• example on figure 2 = long tectonic margins btw Eurasian + North American plates (earthquake + volcanic activity)

• oddity = volcanoes + earthquakes in Pacific ocean

what happens at a constructive plate margin? (8 bullet points)

• direction of movement = away from each other

• happens because of slab pull + ridge push

• young rock = new lithosphere formed because magma rises to gap when plates move apart + cools/ solidifies

• new material fractures when moving → small earthquakes

• most magma stay below surface but can push up crust → ridges + rifts form

• magma erupts to to surface = lava is runny

• form shield volcano

• examples = (ridge) Mid Atlantic Ridge + (rift valley) East African Ridge

what happens at a destructive plate margin, continental vs continental? (5 bullet points)

• can’t sink into mantle so forced to crumple upwards

• forms fold mountains

• cause shallow focus earthquakes + no volcanoes

• overtime fold mountains compress + grow higher

• example = Himalayan mountain range

what happens at a destructive plate margin, continental vs oceanic? (6 bullet points)

• oceanic = denser so pushed under continental into mantle → subduction

• form deep ocean trench

• continental pushed upwards + buckled into chain of fold mountains

• oceanic melts due to heat from friction = magma

• friction btw plates = earthquakes

• magma rise =composite volcanoes + explosive eruptions

what happens at a destructive plate margin, oceanic vs oceanic? (5 bullet points)

• younger of both plates forces older plate down

• because oceanic plate gets denser overtime

• lead to subduction

• plate melt due to friction → magma

• molten rock meets ocean

• water cool it rapidly

• form island arcs

• example = Caribbean Sea

what happens at a conservative plate margin? (8 bullet points)

• direction of movement = side by side (opposite or same direction)

• move at different speeds

• no subduction

• no gap for magma to rise so no volcanic activity or new lithosphere

• form powerful earthquakes

• plates get stuck as slide past each other → build up of pressure

• released through seismic waves as powerful shallow earthquake

• example = San Andes Fault

what are the primary effects of a tectonic hazard? (4 bullet points)

• property + homes destroyed

• people injured/killed

• ports/bridges/roads/railways damaged

• pipes (water + gas) + electrical cables broken = cut off supplies

what are the secondary effects of a tectonic hazard? (4 bullet points)

• people left homeless + can die from exposure

• tourists put off visiting area

• shortage clean water + lack of sanitation → spread of disease

• repairs/reconstruction = expensive → weaken country’s economy

what are the immediate responses to a tectonic hazard? (6 bullet points)

• issue warnings

• rescue teams search for survivors

• treatment for injured

• provide shelter, food, drink

• recover bodies

• extinguish fires

what are the long-term responses to a tectonic hazard? (6 bullet points)

• repair/rebuild properties + transport + infrastructure

• improve building regulations

• restore utilities (water/gas/electric)

• resettle locals elsewhere

• develop opportunities to recover economy

• install better monitoring tech

why is ‘way of life‘ a reason as to why people live at risk from tectonic hazards?

• feel chance of hazards = slim because always lived there

• this means that

• no reason to leave, cheaper, strong family ties, feel prepared + safe

why is ‘geothermal energy‘ a reason as to why people live at risk from tectonic hazards?

• availability of cheap energy supply

• this means that

• cheaper way of living, affordable, less polluting energy

why is ‘family + friends‘ a reason as to why people live at risk from tectonic hazards?

• loved ones there

• this means that

• hard to move away, can’t afford new house because costs more

why is ‘tourism‘ a reason as to why people live at risk from tectonic hazards?

• opportunities for tourism sector, more jobs available to deal with tourists

• this means that

• more money, boosts economy, multiplier effect, more job opportunities

why is ‘resources - fertile soils/minerals‘ a reason as to why people live at risk from tectonic hazards?

• volcanic soils = fertile because weathering volcanic rock release K

• this means that

• cheaper to grow crops because no need to buy fertiliser → more money to sell → more profit