Module 6 Flashcards
Zones of earthquakes
1) Divergent boundaries (new crust formation, magma emergence)
2) Convergent boundaries (subduction, compression, heat, friction)
Divergent boundary
Linear feature that exists between two tectonic plates that are moving away from each other. Divergent boundaries within continents initially produce rifts, which eventually become rift valleys.
Examples include:
Mid-Atlantic Ridge
East African Rift System
Convergent boundary
Where two or more lithospheric plates collide. One plate eventually slides beneath the other (subduction). The subduction zone can be defined by a plane where many earthquakes occur.
Examples include:
Pacific Ring of Fire
Himalayas
Transform boundary
Fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subduction zone.
Examples include:
San Andreas Fault in California
Zones of effusive volcanic eruptions (mafic)
Oceanic hotspots + divergent boundaries.
Thermal plume heats crust, causing expansion, swelling, cracking, and fracturing
Zones of explosive volcanic eruptions (felsic)
Characteristics of a volcanic region
- Increased rainfall, by forcing moist air to rise and form clouds
- large areas of bare ground
- Soils are young and fertile
- biologically diverse with many habitats
Weather vs Climate
Weather: is what conditions of the atmosphere are over a short period of time
Climate: is how the atmosphere “behaves” over relatively long periods of time.
High and low pressure systems
High pressure region: Regions of sinking air are called highs
- Dense air is forced downwards
- Clear skies and fair weather
Low pressure region: Regions of rising air are called lows
- Air is dragged in and forced upwards
- Clouds, rain and strong winds often occur in these regions.
Hailstorms
Hail is precipitation that falls in the form of ice…
Depth of earthquake focus at convergent boundaries
Shallow/ deep focuses
1) Deep: up to 700km, occurs from friction of descending plate
2) Shallow: occurs from movement along fault lines (fold mountains) or rocks displacing when magma rises/falls
Depth of earthquake focus at divergent boundaries
Only shallow focus
Cause of earthquakes
Sudden slip on fault- when stress on edge overcomes friction, earthquake releases seismic waves
Earthquake hazard: Ground motion
Earth shakes from seismic waves, creates infrastructure destruction and fatalities.
Eg. Turkey earthquake October 30th 2020 → building collapse, “locals search for residents trapped in debris of collapsed building”
Earthquake hazard: Tsunamis
Displacement of sea floor displaces water above it, generating large waves
Eg. Indian Ocean earthquake (9.1-9.3 magnitude) created tsunami → epicentre off the west coast of Northern Sumatra → 227,898 dead
