Deck 3 - Tectonics: Earthquake hazards and factors impacting risk and vulnerability Flashcards
What force causes earthquakes to occur?
Friction
How does friction result in an earthquake?
Friction causes tectonic plates to slow or stop in their movement past each other leading to the build up of pressure. When the friction is overcome, the pressure is released as an earthquake.
What is released during an earthquake?
Energy is released as seismic waves
What is the point in the ground where an earthquake begins called?
Focus
What is the point on the surface directly above where an earthquake begins called?
Epicentre
What is the plane along where the plates move called?
Fault plane
What depths do earthquakes with a shallow focus occur at?
70km or less
What depths do earthquakes with an intermediate focus occur at?
70-300km
What depths do earthquakes with a deep focus occur at?
300km+
What is the difference between body and surface waves?
Body originate and travel within Earth’s whereas surface waves form and travel on the surface
What are two types of body seismic wave?
Primary and secondary waves
What are two types of surface seismic waves?
Rayleigh and love waves
What are the characteristics of primary waves?
Travels the fastest, smallest amplitude, compressional wave that cause the Earth to move horizontally in the same direction as the wave is travelling
What are the characteristics of a secondary wave?
Travels the second fastest, have a higher amplitude than primary waves and produce vertical movement as the ground moves perpendicular to the direction the wave is travelling
What are the characteristics of love waves?
Travels more slowly and has a large amplitude. Love waves move the ground horizontally back and forth as they move forward