Tectonic processes and hazards Flashcards
(29 cards)
What is a destructive (convergent) plate boundary?
When an oceanic and continental plate converge, so the oceanic plate is forced under the continental plate
Earthquakes along the Benioff zone
Underwater volcanoes
e.g along the West Coast of South America
What is a constructive (divergent) plate boundary?
When two plates (usually oceanic) diverge
Rift volacones form (less explosive)
Small, frequent earthquakes
e.g between the Nazca and Pacific plates
What is a transform (conservative) plate boundary?
Where two plates move alongside eachother
Powerful, shallow focus earthquakes
e.g between the Pacific and North American plates
What is a collison plate boundary?
When two continental plates converge
Earthquakes likely to have a shallow focus
e.g between Altipino and South American plates
What are the exceptions to tectonic activity at plate boundaries?
Intraplate earthquakes (e.g the New Madrid seismic zone, US) or hotspot volcanoes (e.g Hawaiian volcanoes)
What is a primary (P) wave?
Body waves
Spread quickly from a fault
Can travel through liquid, so every layer of the earth
Least destructive
What is a secondary (S) wave?
Body waves
Can only travel through solid rock
Slower than P-waves
What are Love waves?
Surface waves
Have a high amplitude and travel quickly
Cause the most damage to buildings (shaking side-to-side)
What are Rayleigh waves?
Surface waves
Have a rolling motion
Most of the shaking felt is due to these
What is the Pacific Ring of Fire?
An area known for its string of volcanoes and seismically active sites. Along much of the Ring of Fire, plates meet at convergent boundaries (subduction zones)
Why are there lots of tsunamis in the Pacific?
Because plate boundaries are convergent, which is where the biggest earthquakes occur
Is it possible to predict tsunamis and provide early warning systems?
It is impossible to predict a tsunami because it is impossible to predict earthquakes
But it is possible to provide an early warning system (e.g Indian and Pacific oceans)
Why was the Indian Ocean Tsunami warning system established?
The early warning system was implemented after the 2004 Boxing Day Tsunami in the Indian Ocean. At least 225,000 died across a dozen countries
What is Degg’s model?
Shows that a natural disaster only occurs if a vulnerable population is exposed to a hazard
How does human geography relate to hazards?
Human geography tells us important factors that contribute to a country’s ability to cope with hazards e.g a poor country will be more vulnerable to hazards because they have less money to invest in to health care
What is a multiple-hazard zone? (MHZ)
An area at risk from multiple natural hazards (e.g. California, the Philippines, Japan)
Why is it important to name MHZs?
Because a country may get more support from international aid agencies and more resources to help with hazard management
Why are large urban areas often zones of multile-hazard risk?
They are centres of economic development
Rapid urbanisation (sometimes poor quality housing)
High population densities
Why is the Philippines a multiple-hazard zone?
It sits across a major convergent plate boundary (both earthquakes and volcanoes)
Its northern and eastern coast face the Pacific (most tsunami-prone ocean)
It has a tropical monsoon climate (heavy annual rain = floods, landslides, exarcerbated by steep topography and deforestation)
There are about 24 active volcanoes
What human factors also but the Philippines at risk?
It is an emerging country. Rapid urbanisation and population growth
Many of the poor live in coastal areas - poorly constructed houses and infrastructure - sea surges, flooding, tsunamis
Case study examples of hazards in the Philippines?
2013 Bohol earthquake - landslides, soil liquefaction
Typhoon Haiyan 2013 (just 3 weeks later)
What are the stages of the hazard management cycle?
Mitigation - preventing hazards/minimising their effects
Preparedness - preparing to deal with a hazard event
Response - responding effectively
Recovery - getting back to normal
What does the Park Model show?
How a country responds to a hazard event, how long it will take to recover
What are advantages of the Park model?
It is easy to interpret
It enables different events to be compared
