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32 Cards in this Set

  • Front
  • Back
Artificial Control of natural Processes
1. Minimal effect, and can often serve to increase the problems related to the hazard.
Global Climate and Hazards
1. Global and regional climatic change may significantly affect the incidence of hazardous natural events such as storms, landslides, drought, and fires.

2. Sea level will rise, increased flooding and desertification (could cause wars)

3. Worse weather-related disasters (more frequent and higher magnitude).
Population increase and hazardous events
1. The greatest loss to life during natural disasters has occurred when people are concentrated into smaller and smaller areas.

2. High-rise construction, as well as lax building standards, has led to losses during earthquakes to the tune of 100’s of thousands of people in single events.
Land-use change and hazardous events
1. Higher population sizes also increase the rate at which natural resources are used. This can increase the rate of activities that would or may cause the problem, or it can increase the problem.
1. Energy released by sudden movement of the rocks at or beneath the ground surface.

2. Focus
place beneath the surface where the energy was released.

3. Epicenter
place on the earth’s surface above the focus.

4. There are approximately 1 million earthquakes felt by people each year.
1. Describes the severity of the shaking during an earthquake

2. Modified Mercalli Scale
1. Measure of the energy released by an earthquake

2. Reported using the modified Richter scale where each level is 10 times greater than the one before it.
Earthquake Locations & Processes
1. Plate Boundaries

2. Volcanoes

3. Faults
Earthquakes Caused by Human Activities
1. Loading the Earth’s crust, as in building a dam and reservoir

2. Disposal of waste deep into the ground through injection wells.

3. Underground nuclear explosions.
Earthquake Damage
1. Shaking and ground rupture

2. Liquefaction

3. Landslides

4. Fires

5. Disease

6. Tsunamis
Earthquakes -Usually stupid people
1. Since we know where most earthquake activity will occur, you would think that we would not build there, but no!

2. Most earthquakes, at least since the early 1900’s, have occurred where they occurred before.

3. You can see the San Andreas and other transform faults (Iran) from space. They are not very well hidden by nature.
Tsunami Activity
1. December 28, 2004

2. Over 300,000 dead

3. Entire villages wiped off the face of the map

4. San Diego- 1812, 1927, 1960
Volcanism & Volcanoes
1. Volcanoes form where magma reaches the surface.

2. Volcanic activity can vary from the quiet type, such as found in Hawaii, or explosive types, such as Mount St. Helens.

3. Volcanic Activity can include:
Hot, sometimes poisonous gases

Incendiary mixture of gases and ash

Lava flows

Volcano Types
1. Cinder Cone

2. Shield

3. Composite- Stratovolcano
Cinder Cone
1. More explosive or spattery eruptions

2. Higher viscosity magma
1. More fluid eruption
2. Characteristically basaltic (oceanic)
3. Very large, with gentle slopes
Composite- Stratovolcano
1. Mixture of spattery and fluid eruptions

2. Broad slopes and steep caldera
Volcanic Hazards
1. Lava Flows – The Frankenstein Monster of Threats

2. Pyroclastic Activity
Ash Fall

Ash Flows

Nuee ardentes
Glowing cloud over 500 degrees C.

3. Poisonous gases
Buildup in Calderas (Lake nyos in Africa)

4. Debris flows and Mudflows (Central and South America)
Examples of Volcanic Hazards
1. Mt. Pinatubo
Philippines, June 15 and 16, 1991

Second largest volcavic eruption of the twentieth century.

300 deaths, could have beev more, but the area was ordered evacuated

Also resulted in the death of Pierce Brosnan’s wife from Dante’'s Peak.

2. Mount St. Helens
May 18, 1980

The eruption was unique and complex.

It had been dormant for 120 years.

The eruption occurred with a lateral blast to the north and northwest leveling everything before it.

54 people died and 800 million board feet f lumber was flattened.
Volcanoes- Usually Stupid people
1. If you live near a volcano, particularly one that has erupted in historic time, it may erupt again.

2. If you want to avoid volcanic eruptions, don’t live near a volcano.

3. If you are a poor farmer in Mexico out plowing your field one morning, and you see several volcanoes in the area around your farm, and you have a very fertile and young soil, and there is a smoke coming out of the ground in your field one morning, then you can be surprised that a volcano is now forming in your field, but not that there was a chance of it.
Landslides & Subsidence-Slope Processes & Types of mass wasting
1. Mass wasting

2. Fall

3. Slide

4. Slump
Landslides & Subsidence- Mass wasting
the downslope movement of 1. rock or regolith under the influence of gravity.
Landslides & Subsidence- Fall
1. Freefall of rock or regolith through the air.
Landslides & Subsidence- Slide
1. Movement of rock or regolith along a defined surface.
Landslides & Subsidence- Slump
1. Rotational failure in regolith, usually occurs after the slope has been steepened or wetted.
Rates of movement
1. Creep

2. Flow

3. Avalanche
Human use and Landslides
1. Many landslides have been caused by interactions of adverse geologic conditions, excess moisture, and artificial changes in the landscape and slope material.
Human use and Landslides
- Timber Harvesting
1. Seen in northern California, Oregon and Washington

2. These areas are characterized by earthflows, soil slips, and debris avalanches.

3. Logging on weak, unstable slopes have increased landslide erosion several times.

4. There is an allegation that logging has increased sediment content of the river flow and the degree of flooding after heavy rainfalls.
Human use and Landslides
- Urbanization
1. Steepened slopes

2. Removal of groundcover

3. Construction Vibrations

4. Decreased infiltration
Minimizing landslide Hazards
1. Drainage Control
Water increases weight and decreases friction.

2. Grading
Decreasing the steepness of slopes

Angle of Repose
maximum angle at which sediment is stable.

3. Slope Supports
Retaining walls

Concrete, Steel or wooden beams

4. Vegetating Slopes
Quickly growing ground cover

But kudzu is a really bad idea.
Snow Avalanches
1. Rapid downslope movement of snow and ice, sometimes with the addition of rock, soil and trees.

2. Thousands occur every year, with some blocks weighing several millions of tons moving downhill at high velocities, sometimes riding on a cushion of air.

3. They occur from oversteepening of the slope and vibration.
Snow Avalanches
- Usually Stupid People
1. Don’t build at the bottom of a steep slope.

2. Don’t steepen a slope that is already steep.

3. Don’t upset the people who live uphill.