The Challenges of Natural Hazards - tectonic hazards Flashcards
Hazard risk
The probability or chance that a natural hazard may take place.
Natural hazard
A natural event (for example an earthquake, volcanic eruption, tropical storm, flood) that
threatens people or has the potential to cause damage, destruction and death.
Conservative plate margin
Tectonic plate margin where two tectonic plates slide past each other.
Constructive plate margin
Tectonic plate margin where rising magma adds new material to plates that are diverging or moving apart.
Destructive plate margin
Tectonic plate margin where two plates are converging or coming together and oceanic plate is subducted.
It can be associated with violent earthquakes and explosive volcanoes.
Earthquake
A sudden or violent movement within the Earth’s crust followed by a series of shocks.
Immediate responses
The reaction of people as the disaster happens and in the immediate aftermath.
Long-term responses
Later reactions that occur in the weeks, months and years after the event.
Monitoring
Recording physical changes, such as earthquake tremors around a volcano, to help forecast when and where a natural hazard might strike.
Plate margin
The margin (or boundary) between two tectonic plates.
Planning
Actions taken to enable communities to respond to, and recover from, natural disasters, through measures such as:
emergency evacuation plans, information management, communications and warning systems.
Prediction
Attempts to forecast when and where a natural hazard will strike, based on current
knowledge.
This can be done to some extent for volcanic eruptions (and tropical storms), but less reliably for earthquakes.
Primary effects
The initial impact of a natural event on people and property, caused directly by it, for instance the ground buildings collapsing following an earthquake.
Protection
Actions taken before a hazard strikes to reduce its impact, such as educating people or improving building design.
Secondary effects
The after-effects that occur as indirect impacts of a natural event, sometimes on a longer timescale, for instance fires due to ruptured gas mains resulting from the ground shaking.
Tectonic hazard
A natural hazard caused by movement of tectonic plates (including volcanoes and
earthquakes).
Tectonic plate
A rigid segment of the Earth’s crust which moves across the heavier, semi-molten rock below.
Continental crust is less dense, but thicker than oceanic crust.
Volcano
An opening in the Earth’s crust from which lava, ash and gases erupt.
Named example of a earthquake in a HIC:
L’Aquila, Italy
6th of April 2009
6.3 magnitude
L’Aquila, Italy: Primary effects (deaths and damage)
308 people died
1,600 people were injured
more than 65000 became homeless
the water supply into Paganica was damaged, cutting them off from vital water supplies
L’Aquila, Italy: Secondary effects (aftershocks and infrastructure)
aftershocks that caused further damage after the initial earthquake
all the telecommunications and electricity infrastructure was up and running in less than 24 hours
L’Aquila, Italy: Immediate responses (shelter and support)
homeless people were given shelter, food, drinks and medical attention - they also got free mobiles to communicate with their families
the army, medical personnel, and the fire department all helped clear the wreckage
the immediate response was helped by the fact that L’Aquila is closer than 100km to Rome and Italy is a relatively rich country
L’Aquila, Italy: Long-term responses (rebuilding)
city centre was rebuilt to try rehouse the 65,000 people who had become homeless
the inability of modern buildings to cope with earthquakes was investigated
7 people were tried for manslaughter for not giving strong enough warnings about the earthquake
Named example of a earthquake in a LIC:
The Nepal earthquake in 2015
7.8 magnitude
April 2015
Caused by the collision of the Indo-Australian and Eurasian plates
Nepal: Primary effects
9,000 killed
19000 injured
US$5 billion worth of damage
Nepal: Secondary effects
flooding and damages to the roads from landslides
an avalanche on Mount Everest which killed 19 people
Nepal: Immediate responses
overseas aid from NGOs (non-governmental organisations) such as Oxfam
300,000 people left the capital city
Nepal: Long-term response
an international conference to appeal for funding
Constructive plate margins: Why? Any land forms formed?
Why? - ridge push
Land forms formed - new land, oceanic ridges
Destructive plate margins: Why? Hazards?
Why? - ridge push, slab pull
Hazards - volcanos, earthquakes
Conservative plate margins: Why? Any land forms formed? Hazard?
Why? - convection currents
Land forms formed - fault lines
Hazard - earthquakes
