Midterm #1 Content Flashcards
What’s the most frequent natural hazard in Canada?
Floods
Differentiate between a hazard, disaster and catastrophe
Hazard < disaster < catastrophe.
Hazard: natural event that is a potential threat to human life/property.
Disaster: hazardous event that occurs over a limited time in a defined area
Catastrophe: massive disaster that requires significant amount of money or time to recover
Uniformitarianism: “The ______ is the key to the _____.”
present; past
Prediction vs. forecast
Prediction: specific date, time, and magnitude of event
Forecast: range of probability for the event
Some hazards can be predicted; most can be forecasted.
What is the internal structure of earth, from outside to in?
Crust > Lithosphere > AsthenosphereW
What are the types of plate boundaries?
Divergent: Ocean spreading.
Convergent (subduction): ocean-continent. Ocean plate sinks beneath continental plate.
Convergent (subduction): ocean-ocean. Ocean plate sinks beneath other ocean plate.
Convergent (collision): continent-continent. They compress.
Transform (ocean-ocean or continent-continent): Plates slide.
What created the Himalayas?
India crashing into China
What are the hazards of different plate tectonics/boundaries?
Divergent = earthquakes and volcanoes
Transform = earthquakes
Convergent subduction = makes volcanoes and earthquakes
Convergent collision = makes mountains and earthquakes
What is faulting?
Process of fault rupture. Sliding one rough board past another.
Differentiate between a normal, reverse, and strike dip-slip fault.
Normal: Hanging wall moves DOWN relative to footwall. TENSIONAL stress.
Reverse: Hanging wall moves UP relative to foot wall. COMPRESSIONAL stress.
Strike: Crust moves. SHEARING stress.
What does the Richter scale measure?
Earthquake magnitude.
Strong = 6-6.9, Major = 7-7.9, Great = 8+
What plate boundary is the site of the largest earthquakes?
Subduction zones
What natural hazard is most closely linked with earthquakes?
Landslides
How do humans contribute to causing earthquakes?
- Loading earth’s crust, like building a dam or reservoir, adding weight or creating new faults/lubricating old ones
- Injecting liquid waste deep into the ground through disposal wells, creating pressure on faults
- Creating underground nuclear explosions
Approximately 2/3 of active volcanoes are within the ______ __ _____.
Ring of Fire
What is the ring of fire?
Surrounds the Pacific Ocean basin.
Subduction zones are responsible for this.
A large, continuous, horseshoe shape of volcanoes, both under water and above ground
What have been some of the biggest disasters in the ring of fire?
- Mount St Helena, Mount Rainer, Mount Lassen in the US
- Mount Fuji, Mount Uzden in Japan
Magma properties are describes by _______ ________ and amount of ________ ________.
silica content; dissolved gases
What do viscosity and volatile content mean regarding magma?
Viscosity: resistance to flow
Volatile Content: Determines how explosive the eruption will be
What are stratovolcanoes?
Big cone shaped mountains. High viscosity magma. Lava does not flow far, resulting in steep sides (cone!). Can be extremely explosive; responsible for 80% of eruptions. Common in the Ring of Fire.
What are lava domes?
Small dome with steep sides. Made from highly viscous magma; highly explosive eruptions. Common in the Ring of Fire.
What are shield volcanoes?
LARGEST volcanoes in the world. Wider than they are tall. low viscosity, low volatile content. Gently flowing lava, generally non-explosive.
What are cinder cones?
Cone shaped with a summit crater. Low-intermediate explosivity. AKA Scoria cones.
What are Continental Caldera?
Large summit depression. Collapse of the land surface or volcanic edifice. VIOLENT explosions. They form by explosion of a stratovolcano, which collapses.
How do earthquakes cause a tsunami?
1) Seafloor movement (common)
2) Triggering a landslide
How big must an earthquake be to trigger a tsunami?
M = 7 or greater
What is the four stage process of a tsunami?
1) Earthquake uplifts or downshifts the seafloor
2) Tsunami moves rapidly in deep ocean
3) Tsunami nears land, loses speed, gains height
4) Tsunami moves inland, destroying everything in its path
What was the world’s largest earthquake and therefore tsunami?
2004 Indonesian Tsunami
Most lethal in recorded history
Education (lack of) was a major reason for so many deaths
Killed people on both sides of indian ocean
How can we minimize the tsunami hazard?
- Detection and warning
- Structural control
- Land use
- Run maps
- Probability analysis
What are the evacuation stages for a tsunami in British Columbia?
1) Evacuation order; leave the area.
2) Evacuation alert; be ready to leave on short notice.
3) Declaration of local state of emergency
4) Evacuation rescinded; all good
Differentiate between tsunami warning, advisory, and watch
Warning > Advisory > Watch.
Warning is the highest level. Imminent threat.
Advisory is the second highest level. Potential threat.
Watch is the third highest level. No confirmation of threat, but maybe.
What are the 3 types of landslides?
Falling: free fall of earth material
Sliding: movement of material as a coherent block
Flow: movement of unconsolidated material; very slow
What are the two common types of avalanches?
1) Loose snow
2) Slab avalanches
How can landslides be prevented?
1) Drainage control
3) Grading; increases slope stability (making a soil cement wall)
3) Slope supports; retaining wallsW
What was the event of La Conchita?
BIG LANDSLIDE
What are the three tpyes of magma, based on silica content? (Low to high)
Basaltic, andesitic, rhyolitic (BAR)
