Introduction

• What causes earthquakes?

  The release of frictional force/energy when tectonic plates move against each other.
• Where do earthquakes occur?

  85% in Circum-Pacific Belt

  15% in Mediterranean-Asiatic/Alpine belt

  5% in interior plates e.g. at yellowstone 1k-3k Mag 2.0/year

  Mid-atlantic ridge produces very deep earthquakes

  ~150,000 earthquakes/year
• Characteristics

  Shallow (0-70km), intermediate 70-300km), deep (300-700km)

  Shallow at constructive and Conservative

  Shallow + deep in destructive (deep because of fold mountains going downwards and benioff zone)
• Characteristics of waves: Siesmology

  1Focus: point of pressure release

  2. Epicenter: point directly above the Focus

  3. Body waves- slower= more damage

  P-waves (6km/s) S-waves(3.5/s)

  4. Surface waves- slowest

  Raleigh waves (epilictical up, down motion), Love waves (side-side)
• Measuring seismic energy

  Richter scale: open-ended logarithmic scale of seismic energy

  Modified Mercalli scale: Measures intensity of impact and is based on observation and description

  Moment Magnitude Scale (Mw): most accurate in measuring energy and relates to the geology around the EQ for damage output