Chapter 10 Tectonics, Earthquakes & Volcanism Flashcards
Topography
Studies shapes and features of Earth. “The Lay of the land”
Earth’s Topography
Three orders of relief
1st Continents/Oceans
2nd Mountain ranges, plains,
lowlands, mid-ocean ridges
3rd Mountain, hill, cliff, valley
Faults
Large scale fracture in lithosphere
Where movement occurs
Occurs at plate boundaries or within plates
Some faults active, others not
Normal Faults
Cliff-steep landscapes
Reverse/Thrust Faults
Creates mountains, volcanoes, earthquakes
Strike-Slip Faults
Result from side-to-side motion
Orogenesis
Birth of Mountains
Oceanic and Continental Plates
Creates Pacific Coast Mountain Range compression causes crust to uplift and buckle.
Ex: Pacific Coast
Oceanic and Oceanic Plates
Creates volcanic islands by creating a deep ocean trench forcing magma upward.
Ex: Southwestern Pacific to
Western Pacific
Continental and Continental
Plates
Both plates are light forming large mountain ranges.
Ex: Himalayas
When Earthquakes occur what happens?
Release of built-up energy caused by stress in rock
Occur when new faults are formed
Occur when existing faults move
Focus
Location at which earthquake originates inside earth
Epicenter
Location at the surface of the Earth that is directly above the focus
Foreshock
Earthquake before main shock
Important for large earthquake forecasting
Aftershock
Earthquake that occurs after main shock
Shares general area of epicenter
Magnitude
The amount of ground shaking
Earthquake Measurement
Moment Magnitude Scale
Formerly the Richter Scale
Each number represents 10 times increase of ground shaking
Liquefaction
The conversion of unconsolidated
material into liquid state caused by movement, pressure, and presence of water
San Francisco 1906
Most famous U.S. quake - April 18th at 5:12am - 7.9 magnitude - 450-700 dead - Fires caused more damage than quake itself
Tsunami
Seismic Sea Wave (not tidal)
- Caused by earthquakes at sea
Volcanoes
Four types
- Composite (Stratovolcano)
- Shield
- Cinder Cone
- Dome
Volcano Activity Categories
•Active
- Erupted within recorded history
• Dormant
- Evidence of activity, but not observed
• Extinct
- No sign of activity
- Severe erosion, well-developed soil,
lush vegetationComposite (Stratovolcano)
Largest Volcano
Violent, explosive eruptions
Layer of lava and tephra
Examples: Mt. St. Helen and Mt. Shasta
Shield
Very Wide Circular Exterior Lava flows slowly in all directions Effusive eruptions Example: Hawaiian Islands
Cinder Cone
Most Common type of volcano Small, cone shaped hill Low in elevation Top formed cinders during eruption Emits pyroclastic flow/cinder rock Example: Northern Arizona
Dome
Small to medium sized Explosive eruptions Composed of felstic lava Cooling of lava creates cylinder shape Slope created from erosion Examples: Lassen Peak, Mono-Inyo Craters
Earthquakes occur when
Faults form and move
The San Andreas Fault is an example of
Strike-Slip fault
