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.
