Geological Hazards

Landslides involve gravity, while earthquakes deal with pressure between slip planes

• Water weakens earth materials in five ways:
• 1. Weight - Driving masses of slope is increased with water
• 2. Interplay with clay minerals - Water molecules can attach their positive sides with the negatively charged clay surfaces
• 3. Decreasing the cohesion of rocks -Water flowing through rocks dissolves the minerals that bind the rock together
• 4. Subsurface erosion - (Piping) causes a system of caverns which weakens the hill
• 5. Pressure in pores of rocks and sediments -Pressure on sediments and pore water at the surface making a collapse more likely

Limestone (Karst) - formed extensively in the past when the central and southeastern US were flooded by shallow warm ocean water. The removal of water during a drought or pumping of groundwater lessens the internal support.

No, because there would be much less groundwater pumping/removal.

Yes - Sacred Falls, Oahu, Hawaii

Considered to be known as the largest landslides in history

Compares to the PNG event, in that both were underwater landslides which resulted in tsunamis

"Conditions inside the Earth" Shows the curve in which solid earth misses the curve, but not by much.

• 1. Earthquakes
• 2. Bulges in the ground
• 3. Emissions of steam

• 1. Mud flows
• 2. Ash flows
• 3. Ash falls

• Basaltic Volcanism (Shield Volcanoes):
• 1. Hotter Magma
• 2. Less Viscous
• 3. Relatively dry magma
• 4. Gases easily erupted
• 5. "Peaceful Eruptions"

• Andesitic Volcanism (Strato Volcanoes):
• 1. Colder Magma
• "Rhyolites"
• 2. More Viscous
• 3. Wetter Magma
• 4. Gases build up before
• 5. "Angry" explosive eruptions

Oceanic volcanoes are peaceful - Volume of magma released is larger in spreading centers.

Cause the tall mountains seen at the edges of the continents, but the volume of magma released at subduction zones is small compared to that of spreading centers.

Subduction zone volcanoes are explosive

• Shield Volcano: Flows easier, 15° (Hawaii)
• Strato Volcano: Has difficulty flowing, 45° (Andes, St. Helens, Fugi)

Basaltic "Shield" Volcano

Pieces of the Earth's crust hurtled from the volcano as projectiles

Volcanic depressions; formed by roof collapse into partially emptied magma reservoirs

Icelandic Volcanic eruption

Hurricanes convert the heat energy of the tropical ocean into winds and waves

Warm tropical waters in the Atlantic only occur during summer months.

Coriolis Effect; point of the surface facing eastwards by its rotation. Entrained more at low latitudes

Lack of warm tropical water prevents its strengthening, and also breaks up due to the landscape

• Failures in:
• 1. Land-use planning
• 2. Evacuation

Shape of the river is important - (Two humps) result of flooding and dumping of sediment - during the spring lots of water is dumped on the city - reason it is important is because New Orleans levee was made to accommodate the flooding from the Mississippi and not a storm surge from a hurricane like Katrina.

Rapid combination of oxygen with carbon, hydrogen, and other elements of organic material that produces flame, heat, and light.

• 1. Heat
• 2. Fuel
• 3. Oxygen

Absent one of there, and a fire cannot burn

No - Wisconsin fire was much worse

Tornadoes - up to 500 km/h winds in its weather system

Tornado scale probably more empirical than the Richter Scale - Have a set range of wind velocities - more empirical and less precise. Applies to the hurricane category scales as well.

Makes the system unrestrainable- Forces enormous condensation, releasing massive amounts of latent heat and resulting in higher wind speeds

False - Mostly occurs in the spring, but can occur anytime

False - Tornadoes do not discriminate, but because city buildings are generally stronger, there is less perceived damage.

• Magnitude - 6.9
• 1. Largest recorded earthquake in Idaho
• 2. Surface faulting associated with the earthquake
• 3. Geologic effects included rockfalls and landslides, water fountains and sand boils, changes in the flow of spring water, and water well levels

• Magnitude - 6.8
• 1. 25,000 killed, 19,000 injured and 500,000 homeless
• 2. 16.2 Billion dollars in damages
• 3. Surface faulting of 10km occurred

• Poor Building Codes/Lack of enforcement
• Bad timing (children at school)
• Power plants/hospitals destroyed

• Magnitude - 6.9
• 1. Killed 63 people
• 2. Occurred during the world series

• 200-300,000 deaths
• Lack of fortified housing and the fact that most of the housing was built on soil containing fluids led to liquefaction, in which all of the support structure collapsed.

Drives plate tectonics - expels heat from the Earth

• Worst hit from the tsunami generated from the earthquake off the coast of Sumatra.
• 167,000 died and many more were injured

Result of education about tsunami evacuation to the public - Earthquake caused spontaneous self-evacuation. Out of the 500 residents, only 3 died

• *Was not a very large earthquake (6.8)
• 1. 2200 people killed
• 2. 10 villages eradicated
• 3. No far field tsunami

Generated by underwater delayed landslide (slump) triggered by the earthquake

• *Tsunami wasn't picked up at the Alaska west coast DART sites, but a new station close to the epicenter recorded the tsunami. Was interpreted that there was not a large source size, which allowed them to call off the alert.
• 1. First successful operational use of DART sensors to call off an alert

• 1. Generation into shallow water
• 2. Generation where there is an island, not water

• 1. Harbor struck 8.5 hours after seismic O.T
• 2. Damage reached 700,000
• 3. Wave height reached 1.7m

Pillared structures

• 1. Small dimension of the structure and steep slope minimize obstruction to the tsunami
• 2. Run up observed is very low

Uses a pressure sensor at the bottom of the ocean to detect the overpressure caused by the passage of the tsunami. Then relays information by satellite through a bouy

• 1. Very complex technology - expensive to build, deploy, and maintain
• 2. Vandalism