1.5A measuring magnitude and intensity

• magnitude = size of the tectonic event
• Moment magnitude scale (MMS) =

  • measures the energy released during an earthquake
  • related to the amount of slip on the fault lane and the area of movement on the fault plane
• Mercalli:

  • measures earthquake intensity on a scale of I-XII
  • cannot be used to easily compare earthquakes as shaking experienced depends on building type and quality, ground conditions and other factors
• Volcanic explosivity index:

  • measures that magnitude of a volcanic eruption