Environmental Hazards Flashcards
What happens at conservative plate boundaries and where are they found
Found between the Pacific and North America plate. Plates slide past each other. Movement isn’t smooth and pressure build up until plates jerks past each other. Cause earthquakes
What happens at collision plate boundaries and where are they found
Found between Indian and Eurasian plate boundaries
Two continental plates move together. Crust is too light to sink so it’s forced upwards as plates move together. Causes mountain ranges and earthquakes
What happens at destructive plate boundaries and where are they found
Found at Eurasian and Pacific plate. 2 plates moving together. Involves the oceanic plate and continental plate. Oceanic plate is heavier so is pushed down to the mantle where it melts. This forces magma into the earth. Can form fold mountains and cause earthquakes
What happens at constructive plate boundaries and where are they found
Found between the Pacific and Naza plate. When two plates move apart. The crust cracks and splits moving apart allowing magma to reach the surface. Cause volcanic eruptions and sometimes earthquakes
What types of volcanoes are there
Still active
Dormant
Extinct
Where are volcanoes distributed around the world
Active volcanoes occur mainly along fault lines or plate boundaries at edges of tectonic plates. Can occur at destructive or constructive plate boundaries. Volcanoes are confined to specific belts or areas. Around the Pacific Ocean, active volcanoes form the ring of fire. In the centre of the Atlantic Ocean, a line of volcanoes form the Mio Atlantic Ridge
Describe the Mount St Helen Eruption
Erupted on 18th May 1980 at 08:32 in Washington State, West Coast of USA
What caused the Mount St Helen Eruption
It lies close to a destructive plate boundary where the smaller Juan de Fuca plate is being forced under the North American Plate
What impacts on the landscape did the Mount St Helen Eruption have
All plant and animal life living within 25km radius were killed, including full grown trees by blast and pyroclastic flow. The eruption left a horse shoe shaped crater 1-2 miles wide and 0.5 miles deep. Lahars poured down the valley below killing fish, choking rivers with rock debris and ripping trees from their roots
What impact on the people did the Mount St Helen Eruption have
61 people died and 198 people had to be rescued. Mudflows destroyed roads, bridges, houses and logging camps. The exposition flattened buildings and trees destroying power supplies. Ash clouds resulted in flights being cancelled. Ash caused £100 million damage to farming industry and crops. Ash clogged up car engines. Tourists no longer visited area causing reduction in economy
How could scientists have predicted the Mount St Helen Eruption
Measuring the frequency of earthquakes on the mountain ( greater the frequency, nearer the eruption ). Measuring the size of the volcanic cone to show the build up of magma in the vent. Increasing numbers of sulphur dioxide at the crater could indicate an eruption. Increase in water temperatures could indicate an eruption
How effective are prediction methods for volcanic eruptions
Scientists can’t give precise dates of any eruptions. Scientists didn’t predict that the Mt St Helen Eruption blast would occur on the north face which resulted in people being killed outside the exclusion zone
Describe short term aid of Mt St Helen Eruption
Parts of St Helens were closed off just before the eruption to reduce the loss of life however it wasn’t effective as the exclusion zone was inaccurate. Rescue centres were set up which helped shelter those who had lost their home. Ash was cleared up which took 10 weeks and cost £1 million. Electricity was restored to the area. 200,000 people were temporarily employed to clean up minor damage to clear roads to resume traffic.
Describe long term aid of Mt St Helen Eruption
US Government gave $145 million to rebuild houses, repair roads and construct a new highway for locals. Millions of trees were replanted which restores the oxygen that the trees provide to area. Local rivers were dredged to remove logs and levees which reduced flooding. Farmers were compensated for loss of crops. $50 million of federal money was invested into Mt St Helen Visitor Centre to help attract visitors back to area. $1 million was spent to remove 1 million tonnes of ash from roads and airports.
Describe effectiveness of aid from Mt St Helen Eruption
The money given by the federal government allowed quick recovery. Tourism is more popular than ever. Environmentally, the area has taken longer to restore. Trees will not fully grow back until 2059 meaning normal levels of wildlife won’t be back to normal until then either.
Describe where earthquakes are located
Found along the edge of tectonic plates. Band of earthquakes around the Pacific Ring of Fire. Most earthquakes occur under the sea. The west coast of North and South American are earthquake zones
How are earthquakes caused
At destructive plate boundaries the plates are moving towards each other and one plate if forced down into the mantle and as pressure builds up the plate jerks. This causes shockwaves that are felt as earthquakes. At constructive plate boundaries, plates are moving away from each other where rocks move and crack apart sharply which causes shock waves to the earths surface. At conservative plate boundaries, plates are sliding past each other and pressure gradually builds up then send shock waves.
What are the 3 types of shock waves
P waves ~ makes rocks move up and down ( fastest ). S waves ~ makes rocks move side to side ( travel up to 2/3 of the speed of p waves ). L waves ~ spread out along waves in the surface ( slowest )
What plates were involved in the Japan Earthquake
Eurasian and Pacific
When was the Japan Earthquake
11 March 2011
What impact did the Japan Earthquake have on people
Cancer risks increased. Approx 19,000 people died. 500,000 people were made homeless and suffered from hypothermia. No electricity or phone lines (destroyed)
What impact did the Japan Earthquake have on the landscape
Coastline shifted 4m to the east. Earthquake caused a tsunami which flooded the land. Fukushima nuclear power plant damaged. Old refineries were on fire.
Effectiveness of Japan’s planning
Majority of buildings survived. Many lives were saved. People knew what to do from the early warning signs. Schools had emergency earthquake kits and regular drills. Within 32 seconds automatic warnings were sent out. The sea wall was breached. Earthquake caused defence walls to sink. People were told to head for higher land but was too far away.
Japan aid
Immediate disaster relief to restore area back to normal. Humanitarian aid like blankets, tents etc to help people who lost homes to keep safe and warm. Disaster victim identification to help find injured/trapped/lost people
How can countries protect against earthquakes
Earthquake resistant buildings ~ deep foundations, rubber shock absorbers and reinforced concrete with steel. Sprinkler systems to prevent fire spreading.
How can countries prepare for earthquakes
Earthquake drills to practice what to do in the event. DROP COVER HOLD. Emergency plans. Supplies collected like water, tinned food, blankets etc. Warning systems
How can countries predict earthquakes
Laser beams can be used to detect plate movements. Seismometers are used to pick up vibrations. Radon gas can escape from cracks in the earth surface
Where are tropical storms located
Only in oceans 30 degrees North and South of the equator
Where are tropical storms distributed
They originate over the eastern side of oceans and move westwards where they then cross land
What causes tropical storms
Occur in sea temperatures over 27 degrees. Very damp moist air spiralling upwards 60% humidity. Low air pressure. Large expanse of water. Location between Tropic of Cancer and Tropic of Capricorn
What impacts did Hurricane Katrina have
$300 billion of damage. 300,000 homes were destroyed. Cotton and sugar cane crops were destroyed. 1 million people were made homeless. Tourism decreased. Forced 16 National Wildlife Refugees to close. 3 million people were left with no electricity.
Describe short term aid for hurricane Katrina
Hundreds of thousands of people were rescued. Other countries sent rescue workers to find trapped people. Rescue equipment to move heavy obstacles. Food and water to help homeless people. Shelters, beds and blankets for people whose homes were destroyed. First aid kits and doctors sent over.
Describe long term aid for hurricane Katrina
Money to rebuild roads, schools, hospitals and housing. Money to help affected victims. Only $44 billion of the $110 billion has been spent on rebuilding the area.
How effect was the aid for hurricane Katrina
Rescue teams and equipment helped to save many lives. Without the temporary shelter, food and doctors many people wouldn’t have survived. The money used for rebuilding the area has not been used very well. Recovery has been slow. 7 years after the disaster and 5,000 people still homeless
Why are the effects of earthquakes and volcanoes much greater in LEDCs than MEDCs
LEDCs have to rely upon and wait for international aid. LEDCs have less money. Buildings in LEDCs are built poorly. LEDCs have less defences and worse prediction rates. LEDCs have low numbers of hospitals and not well prepared
Why is human response quicker in MEDCs than in LEDCs
MEDCs are richer and better prepared. MEDCs have trained emergency services which are always available. MEDCs have warning systems, evacuation routes and earthquake drills.
