Seisimic Hazards Flashcards
How does an earthquake occur?
Crust constantly moving
Slow build up of energy stress
When pressure is released parts of surface experience intense shaking motion
Where do earthquakes occur?
Destructive plate margins
Conservative plate margins marked by a fault
What does the nature of seismic activity depend upon?
Type of boundary
Depth of focus ( shalllwer more damage)
What is the Richter scale?
Logarithmic scale between 3.0 and 7.0
Max wave amplitude
Not the total energy
What scale is more used nowadays instead of the Richter scale?
Moment magnitude scale
Measures size in terms of energy realised
Increase in one unit means 30x more energy and 10x More amplitude
What is the Mercalli scale?
Measures intensity and impact
12 point scale
Roman numerals
What are the primary effects of earthquakes
Ground shaking or ground rupture
What are the secondary effects of earthquakes?(4)
Soil liquefaction
Landslides
Tsunami
Fires
What is soil liquefaction?
When soils with high water content lose mechanical strength and start to. Behave like a fluid
