Earthquakes Flashcards
What is the focus?
The point of fracture, where energy is suddenly released
What is the epicentre?
Directly above the focus
What are faults?
Pressure builds and cracks along the crust fractures
What are the body waves?
Waves that move through the earth’s surface
What does a primary wave move through?
Solids and liquids
What does a secondary wave move through?
Solids
How do primary waves move?
Compresses then expands
How do secondary waves move?
Vertical movement
What are surface waves?
Waves that travel through the surface of the crust
What are the body waves?
Primary and secondary waves
What are the surface waves?
Love and rayleigh waves
How is magnitude measured?
Moment magnitude scale
What is magnitude?
The amount of energy released at the epicentre
What is intensity?
The earthquakes effect on people, structures and natural environment
What scale does the moment magnitude use?
1-10log
How is intensity measured?
Mercalli intensity scale
What scale does the mercalli intensity use?
I - X1
What are the primary effects of earthquakes?
Ground shaking- causes infrastructure to collapse
Crustal fracturing- seismic energy causes the crust to crack at surface
What are the secondary effects of earthquakes?
Tsunami- submarine earthquake
Fire- power line + gas pipes break
Liquefaction- violent shaking leads to surface rocks losing strength
Landslides+ avalanches- ground shakes and places stress on slopes which leads to landslides
What is theory one of intra plate earthquakes?
Stress builds along ancient faults causing them to activate again
What is theory two of intra plate earthquakes?
Crust that was once weighed down by glaciers is rebounding from mantle triggering earthquakes
