The challenges of Natural Hazards Flashcards
(37 cards)
whats the crust ?
The crust varies in thickness (5-10 km) beneath the ocean. Made up of several large plates.
Whats the Mantle?
Widest layer of the Earth (2900 Km thick). The heat and pressure means that the rock is in a liquid state of convection.
Name the part of the Earth that is the hottest section (5000 degrees). Mostly made of iron and nickle and is 4x denser than the crust. The inner section is solid whereas the outer section is liquid.
The inner core and the outer core.
Ash Could?
Small pieces of pulverized rock and glass which are thrown into the atmosphere.
What is the name called that the sulfur dioxide,water vapor and carbon dioxide come out of the volcano?
Gas
Lahar ?
A volcanic mud flow which usually runs down the valley on the side of the volcano.
What is the fast moving current of super heated gas and ash (1000 Celsius ). They travel at 450 mph?
Pyrolastic flow
Volcanic bomb?
A thick (vicious) lava fragment that is ejected from the volcano.
Warning signs of a volcano?
- Small earthquakes are caused as the magma rises up.
- Temperature around the volcano rises as the activity increases.
- When the volcano is close to erupting it start to release gases.
Monitoring techniques of a volcano?
- Siesmometres are used to detect earthquakes.
- Thermal imaging and satellite cameras can be used to detect heat around the volcano.
- Gas samples may be taken and chemical sensors used to measure sulfur levels.
Preparation for a volcano ?
- Creating an exclusion zone around the volcano.
- Being ready and able to evacuate residents.
- Having an emergency supply of basic provisions such as food.
- Trained emergency services and a good communication system.
What is a convection current?
The crust is divided into tectonic plates that are moving due to convection currents in the mantle.
Explain a convection current
1) Radioactive decay of some of the elements in the core and mantle generate a lot of heat,
2) When lower parts of the mantle molten rock (magma) heat up they become less dense and slowly rise.
3) As they move towards the top they cool down becoming more dense and slowly sink.
4) The circular movements of semi-molten rock are convection currents.
5) Convection currents create drag on the base of the tectonic plate and this causes them to move.
Natural Hazard?
A natural hazard is a natural process which could cause death,injury or disruption to humans,property and possessions.
What type of hazard are hazards caused by the land and tectonic processes?
Geological Hazards
Meteorological Hazard?
These are hazards caused by weather and climate
What causes an earthquake to occur?
Earthquakes are caused when two plates become locked causing friction to build up. From the stress the pressure will eventually be released this triggers the plates to move into new positions. This movement causes energy in the form of seismic waves to travel from the focus towards the epicenter. As a result the crust vibrates triggering and earthquake.
Atmospheric circulation ?
Is the large scale movement of air by which heat is disturbed on the surface of the earth.
Hadley cell?
Largest cell which extends from the equator to between 30 to 40 degrees north and south.
Ferrel Cell?
Middle cell where the air flows pole ward between 60 and 70 degrees latitude.
Whats the name of the cell that the smallest and weakest cell that occurs from the poles to the Ferrel cell?
Polar Cell
Describe the distribution of tropical storms
They are known by many names including hurricanes, cyclones and typhoons. They all occur in a band that lies roughly 5-15 degrees either side of the equator.
Describe the stages of the formation of a tropical storm
1) The suns rays heat large areas of the ocean in the summer and the autumn. This causes warm, moist air to rise over particular areas.
2) Once the temperature is 27 degrees Celsius the rising warm, moist air leads to low pressure. This eventually turns into a thunderstorm. This causes air to sucked in from the trade winds.
3) With the trade winds blowing in the opposite direction and the rotation of the earth involving the thunderstorm will eventually start to spin.
4) When the storm spins faster than 74 mph a tropical storm is officially born !
5) With the tropical storm growing on power more cool air sinks to the center of the storm, creating a calm,clear condition called the eye of the storm.
6) When the tropical storm hits land it loses its energy source and it begins to lose strength. Eventually it will blow itself out.
What are the primary effects of a tropical storm ?
- The intense winds of tropical storms can destroy whole communities,buildings and communication networks.
- As well as their own destructive energy the winds can generate abnormally high waves called storm surges.
- Sometimes the most destructive element of a storm are these subsequent high sea flooding they cause to coastal areas.