Challenge Of Natural Hazards Flashcards
+ Case Study L'Aquila/ Nepal/ Irma/ Beast from the East
What is a natural hazard
Natural hazards are extreme natural events that can cause loss of life, extreme damage to property and disrupt human activities.
Name 3 types of hazards and examples.
-Atmospheric.. Hurricanes
-Tectonic.. Earthquakes
-Geological.. Landslides
List the 8 factors affecting hazard risk
-Time
-Magnitude
-Natural Factors
-Level of development
-Education
-Frequency
-Management
-Population Density
Name 4 layers of the earth
Crust, Mantle, Outer Core, Inner Core.
What state is the crust
Solid
What state is the mantle
Liquid
What state is the Outer Core
Liquid
What state is the Inner Core
Solid
What is outer and inner core mostly made of
Iron and Nickel
What is the widest layer of the earth
Mantle
How are convection currents made (EQ)
1) Radioactive decay of some of the elements in the core and mantle generate a lot of heat.
2) When lower parts of the magma heat up they become less dense and slowly rise.
3) As they move towards the top they cool down, become more dense and slowly sink.
4) These circular movements of semi-molten rock are convection currents.
5) Convection currents create a drag on the base of the tectonic plates and this causes them to move.
What are four types of plate boundaries
-Destructive
-Constructive
-Conservative
-Collision
What happens at a destructive margin
As the plates collide, the denser oceanic plate subducts beneath the continental plate. The friction as the plate sinks causes the mantle to melt to magma causing pressure to build. The magma escapes through weaknesses in rock forming composite volcanoes. Causes earthquakes and volcanoes.
What happens at a constructive margin
Two plates move apart causing new magma to reach the surface through the gap to form shield volcanoes. Can cause earthquakes.
What happens at a conservative margin
Two plates move past each other side by side at different speeds. Pressure is built from the friction causing earthquakes when the energy is released.
What happens at a collision margin
Two continental plates collide, where neither can sink so the land buckles upwards and forms fold mountains. Causes earthquakes.
What is the focus in an earthquake
The point of which pressure is released.
What are seismic waves in earthquakes
Energy waves that travel out from the focus
What is the epicentre in earthquakes
The point directly above the focus, where seismic waves reach first.
What measures the magnitude
The Richter Scale
How do earthquakes happen (EQ
When two plates become lockes causing friction to build up which causing pressure to build. The pressure is eventually released triggering the plates to move into a new position. This movement causes energy in the form of seismic waves to travel from the focus towards the epicentre. As a result, the crust vibrates triggering an earthquake.
What are the two ways of earthquake management
- Predicting
- Prevention
List ways of predicting earthquakes
-Satellite surveying
-Laser Reflection
-Radon gas sensor (Radon gas is released when plates move)
-Seismometer
-Water table level
-Seismic records to predict next event.
List ways of preventing damage from earthquakes
-Build earthquake resistant buildings
-Raise public awareness
-Improve earthquake prediction.
What are features of earthquake resistant buildings (EQ)
-Several emergency staircases and exits to speed up evacuation.
- Deep foundations into solid rock.
-Shock absorbers in foundations to absorb seismic waves
- Roof covering area outside the building to prevent pedestrians being showered with broken glass
-Weights on roof to counterbalance shaking
-Cross braing to provide extra support to strong steel frames.
LIC Case Study: Context of Nepal Earthquake
-On 25th April 2015
-7.8 magnitude
-In Barpak, 80 km NW of the capital Kathmandu
-Eurasian plate and Indian Plate at a collision plate margin
-In the Himalayas
LIC Case Study: What are the primary effects of earthquake in Nepal
-8841 died
-16800 injured
-over 1 million homeless
-modern buildings collapsed due to lack of building regulations
-26 hospitals and 50% of schools destroyed
-352 aftershocks.
LIC Case Study: What are the secondary effects of earthquake in Nepal
-Triggered an avalanche on Mt Everest. 19 died.
- Tourism/Employment
/Income Shrink
-2/3 of population depend on rice farming for food, but rice seed was ruined in rubble causing food shortage and income loss.