Tectonic Hazards - done Flashcards
What is a natural hazard
a natural event that threatens people or has the potential to cause damage destruction and death
Examples of atmospheric hazards
hurricanes
tornadoes
heat waves
droughts
biological hazards
disease
air pollution
How does the relief of land affect the impact
The people at the bottom of a hilly area would be hit harder and it would be more disastrous for them than the people at the top
DIFFERENCES BETWEEN OUTER CORE AND INNER CORE
Outer core - liquid and made of iron and nickel
Inner core - solid from intense pressure
What is the crust and upper mantle referred to
Lithosphere
Describe Slab pull
the denser oceanic plate sinks into the mantle and pulls the rest of the plate with it due to gravtiy
Describe ridge push
Magma rises through the ridge and as it cools it renews the crust. As it slides down the ridge it causes the plates to move away
Oceanic crust is
Newest
not very thick
very dense
Continental crust is
Older
thick
not very dense
Example of a constructive plate boundary
North American and Eurasian plate
Example of a destructive plate boundary
South American and Nazca plate
How do fold mountains form
Under intense pressure when the plates move together they buckle and the rock is forced up
What type of volcanoes are formed at destructive plate boundaries
Explosive eruptions with viscous lava which forms Cone and strato-volcanoes with high gas pressure
Example of a conservative plate boundary
pacific and North American plates
Name of the Fault line in California
San Andreas Fault
Difference between destructive plate boundaries and collision plate boundaries
Destructive - between oceanic crust and continental crust
collision - between two continental crusts
Example of a collision plate boundary
Indian plate and Eurasian plate
Why are volcanoes not found on collision margins
Because the pressure between the plates is too great for magma to pass its way through
What type of volcanoes form on constructive boundaries
Shield volcanoes with runny lava and low gas pressure
Why does magma rise
Driven by buoyancy and gas pressure, the molten rock which is lighter than the surrounding rock forces its way up
Lahar
a mixture of volcanic ash, rocks, and other debris mixed with water. Many move too fast for people to outrun
What is a pyroclastic flow
mixtures of hot, dry ash, rock and gas that travel about 80km/hour and range from 200-700*C
Jolkulhlaup
a flash flood that occurs when a glacier that is on op of a volcano melts
What is tephra
anything that is blown out of the volcano into the air
Two types of earthquake measurement
Mercalli Scale - measures damage
Richter Scale - based upon measurements of seismographs
What is liquifaction
when soft rock is shaken the water comes up and things sink
Reasons why people live near tectonic hazards
- Increase in preparation so people feel safe
- Good job and way of life already
- Volcanic soils are fertile
- Tourism is high = jobs
- Magma contains useful minerals that can be mined after it cools such as gold, silver, zinc, lead, copper
- Poorer people can’t afford to move away
How are Earthquakes predicted
There is no way of knowing for certainty that one is coming but they do monitor small tremors
How are volcanoes monitored
- Sulphurous gases rising
- Heat changes and small vibrations
- Changes in the slope of the volcano
Planning strategies for tectonic hazards
- Hazard mapping - important buildings like hospitals are built in low risk areas
- Emergency supply stockpiling
- Emergency services practise evacuation plans
- Safety protocols and drills
- first aid training
- securing objects/furniture (earthquakes)
Protection strategies for volcanoes
- Steep, sloping rooves so that ash falls off - no collapsing roofs
- Concrete blocks and explosives are used to divert/slow lava flows
How can buildings be protected from earthquakes
- Water tank on top to counteract swaying
- Base isolation
- Automatic window shutters(falling glass)
- Smart metres cutting off electricity
- Cross bracing
- flexible structures
- sea walls in case of tsunamis
Example of a building that has been protected from earthquakes
Taipei 101 in Taiwan - has a giant steel ball that sways and counteracts the shaking
what are the crust and upper mantle called together
the lithosphere
what are tectonic plates
several major fragments of the lithosphere
global distribution of earthquakes
- occur at all plate boundaries (those at conservative plate boundaries are usually small and not violent)
- are both on land and in the sea
- occur in narrow bands along plate margins
global distribution of volcanoes
- occur at constructive and destructive plate boundaries
- are both on land and in the sea
- occur in narrow bands along plate margins
describe how earthquakes occur at conservative plate boundaries
- pressure builds ass the plates are being pulled in opposite directions
- as friction is overcome, the rock fractures in an earthquake
how are volcanoes formed at constructive boundaries
- hot molten lava rises between the plates then cools to form new plate
describe how volcanoes are formed at destructive plate boundaries
- when oceanic and continental plates collide, the denser oceanic plate is subducted under into the mantle where it melts
- hot magma then forces its way to the surface
what is the point where one plate is forced under another called in a destructive plate boundary
subduction zone
immediate responses to tectonic hazards
- issue warnings
- rescue teams
- treatment given
- provide food, shelter, water
- recover bodies
- distinguish fires
long term responses to tectonic hazards
- repair buildings and transport infrastructure
- improve building regulations
- restore utilities
- increase monitoring technology
- resettle locals elsewhere
what are the types of natural hazard
tectonic - earthquakes and volcanoes
geomorphological hazards - flooding
atmospheric - tropical storms
biological - forest fire
factors affecting hazard risk
- concentration of population/number of people vulnerable
- frequency
- magnitude
- wealth of area
