Earthquakes

• Occur when a part of the earth’s crust suddenly fractures and shifts to relieve stress.

• Energy is released in the form of shock waves

The Richter scale

• Measures the intensity of the shockwaves

• Each unit (for example 4 to 5) has 10 times more amplitude

• A magnitude 6 earthquake has 100 times more magnitude than a magnitude 4 quake.

Scale

• <4 insignificant

• 4.0-4.9 minor

• 5.0 – 5.9 damaging

• 6.0-6.9 destructive

• 7.0-7.9 major

• >8.0 great

Primary effects

• Shaking of ground

• Permanent vertical or horizontal displacement of the ground

• Buildings, pipelines, roads, bridges derange

Secondary effects

• Rock slides

• Land slides

• Urban fires

• Flooding caused by subsidence of land

• Coastal flooding

• Tsunamis

Earthquake readiness

• Enforce building code for property in high risk areas

• Limit height of buildings

• Re-inforcing structures

• Monitoring activity

Expected damage from earthquakes in the US and Canada

Volcanic Activity

•Some volcanoes erupt quietly and release flows of molten rock but others erupt explosively and spew large chunks of rock, ash and harmful gases into the atmosphere

Disadvantages:

Advantages:

summizing

Advantages Disadvantages

New rock, new minerals SO2 gas emitted forms H2SO4 (sulfuric acid)

Land forming CO2 gas emitted forms H2CO3 (carbonic acid)

Renews mineral resources Acid droplets reflect sunlight resulting in cooling effect of the atmosphere

Types of rock

Igneous

Basalt

Granite

metamorphic

Produced by pressure and temperature exerted on existing rock

sedimentary

Formed from sediment by weathering and erosion and subsequent cementation

Non-renewable Mineral Resources

Mineral resources are non-renewable materials that we can extract from the earth’s crust.

We extract over 100 nonrenewable minerals from earth’s crust

• Iron Copper• Aluminum Salt• Clay Sand• Phosphates Soild• Coal Oil • Natural gas uranium

Natural Capital

Identified: known location, quantity and quality

Reserves: identified resource from which a usable Nonrenewable mineral can be extracted profitably

Undiscovered: potential supplies based on geologicKnowledge

Other resources: undiscovered identified resourcesNot classified as reserves

How are mineral deposits found?

•Aerial photography•Studying rock outcrops•Radiation measurements•Magnetometer•Gravimeter

• Drilling• Sample extraction• Seismic surveys (detonations)• Chemical analysis

How are buried mineral deposits removed?

Surface mining

• Uses mechanized equipment to strip away overburden of soil and rock which are discarded as spoils.

• Process depends on resource being mined and local topography

• Leaves great environmental damage

• USA Surface Mining Control and Reclamation Act of 1977 requires mining companies to restore land;

• However, strong lobbying of elected officials have weakened the law

Types of surface mining

• Open pit (iron, copper, sand, gravel stone)

• Dredging (underwater deposits)

• Area strip mining (dig trenches and fill them with overburden; leaves wavy series of highly erodible rubble called spoil banks)

• Contour strip mining (used in hilly areas, cuts series of terraces into side of hill; overburden of new terrace is dumped on terrace below)

• Mountaintop removal (using explosives; very damaging to environment; practiced in West Virginia.

Subsurface mining

• Removes coal and ores deep under the surface

• Uses vertical and horizontal shafts

• Disturbs less than 1/10th of the land as surface mining and produces less waste materials.

• More dangerous

• More expensive

• Health hazards

Environmental EffectsExtracting , processing and using mineral resources disturbs the land, harms workers, erodes the soil , produces large amounts of solid waste and pollutes the air, water and soil

Environmental Cost of Mining

• Scarring and disruption of the land surface

• Susidence (land above mine shafts collapses)

• Toxin – laced mingin wastes

• Acid mine drainage

• Toxic emissions from ore processing

Metal ore metal + gangue (waste)

Removing gangue produces tailings

Tailings are toxic and can be carried by wind or leach andContaminate ground waters

Mining has polluted about 40% of western watersheds

Steps Environmental Effects

exploration, extraction

MiningDisturbed land; mining accidents;health hazards; mine waste dumping;oil spills and blowouts; noise;ugliness; heat

Solid wastes; radioactive material;air, water, and soil pollution;noise; safety and healthhazards; ugliness; heat

Processing

transportation, purification,manufacturing

Use

transportation or transmissionto individual user,eventual use, and discarding

Noise; ugliness;thermal water pollution;pollution of air, water, and soil;solid and radioactive wastes;safety and health hazards; heat

Figure 16-13Page 343

Smelting separates pure metal out

Lots and lots of air pollution

Greatest cost of mining to environment..

is not the mining process (or exhausting mineral resources)

BUT

The extraction, processing and conversion to products

To make these

ProducesAbout 6 tons ofMining waste

To make a fistful of gold

Produces the amount of 50 of these

Cyanide heap leaching

Is a cheap way to extract gold from very low grade ore.

Cyanide is toxic and is use to extract 85% of gold from ore.

Who pays for all the damage?

• The companies? NO

• The consumers, by paying a higher price? NO

• HA HA IT’S YOU! THE FUTURE GENERATION.

• Time to wake up

Depletion curve for nonrenewableResource using three sets of assumptions. DashedVertical lines represent times when 80% depletionOccurs.

What does the future hold?

1. Should government subsidize mining ?

2. Should more public land be made available for mining companies

3. Are there technologies out there that can save us?

4. What are metals used for and are there alternatives for them?

how long will we have…

Metal Time

Aluminum 2139

Copper 2039

coal 2158

Gold 2025

http://terresacree.org/aluminiumanglais.htm