Hazardous Earth Flashcards
Why are there differences in Pressure?
Land and sea heat up differently - Dark surfaces on land absorb sunlight, which is converted to heat. Land heats quickly in summer and cools quickly in the winter. The seas take longer to heat and longer to cool. This causes areas of high pressure.
How do ocean currents circulate heat?
In the north atlantic, salt water is heavy and sinks. This sets up a convection current which drags surface water down. The current draws warmer salty water from areas such as the gulf of mexico, nearer the equator. This cools and sinks in the greenland seas, and then flows south towards the equator where its warmed again.
What are the natural causes of climate change?
- Eruption theory - Volcanoes can change the earths climate, ash and sulphur dioxide gas rise they get spread around the stratosphere, stopping sunlight from reaching the earths surface. This cools the planet.
- Sunspot theory - Astronomers observed spots on the sun appear as black spots on the sun. The spots tell us that the sun is more active than usual. This means more solar energy reaches earth and the temperature increases.
What are the human causes of climate change?
- Greenhouse effect - The greenhouse effect is a natural process but humans producing more carbon dioxide than there should be in the atmosphere can increase the temperatures beyond the natural levels.
Where do cyclones occur?
Cyclones are formed over the south pacific and indian oceans. They form at 5 degrees - 30 degrees
Impacts of cyclones/Hazards
Tropical cyclones are one of the biggest threats to life and property even in the formative stages of their development. They include a number of different hazards that can individually cause significant impacts on life and property, such as storm surge, flooding, extreme winds, tornadoes and lighting. Combined, these hazards interact with one another and substantially increase the potential for loss of life and material damage.
What are the layers of the earth?
Crust, lithosphere, asthenosphere, mantle, meopsphere, outer core, inner core.
What are tectonic hazards?
Tectonic hazards occur when the earths plates move. This what causes earthquakes.
What are climatic Hazards?
When a region has certain weather hazards eg flooding, hurricanes etc
Plate tectonics theory -
Slab pull is what is now commonly believed to move the tectonic plates around. They sit on top of the mantle and where older denser tectonic plates sink into the mantle at subduction zones, it pulls newer and less dense sections of plate behind with it.
Where are earthquakes usually present?
Along plate boundaries - BUT ONLY AT CONSTRUCTIVE and DESTRUCTIVE plate margins.
Where are volcanoes located?
Volcanoes are located around the plates. Lots of volcanic activity occurs in the ‘‘ring of fire’’ which is located along the plate margin of the pacific plate.
Define Convergent plate boundaries
A convergent plate boundary, also known as a destructive plate boundary usually involves an oceanic plate and a continental plate. The plates move towards each other and can cause earthquakes
Define a divergent plate.
Divergent plates move away from each other. Magma in the mantle rises up to make new land in the form of a shield volcano
Developed country Earthquake - Japan
On Friday 11th march 2011 a 9.0 magnitude earthquake occured in Japan. The epicentre was 30km below the Pacific Oceanbed. It caused a devastating tsunami.
The waves travelled as far as 10km inland - as far as sendai.
Tsunami flooded an area of approximately of approximately 561 square km.
Ports and airports in Sendai were damaged.
Massive surge destroyed 3 storey buildings where people gathered for safety.
The nuclear power plant melted down.
