Different Types of
Earthquake Measurement Scale:
- Richter Scale: Measures the height of the wave. Loses accuracy in large earthquakes. It is used often so it is good to compare with. Used by scientists.
- Moment Magnitude Scale (MMS): Measures the total energy released. Newer and more accurate. Doesn’t show the damage, but is designed to match the Richter Scale so the numbers are the same for each earthquake. Better for scientists.
- Mercalli Scale: Experienced impacts, descriptions of damage. Measures intensity, easy to understand but has less flexibility. Good for practical purposes as you can access damage levels quickly. Good for locals and aid workers.
Richter
Scale Examples:
- 2-2.9: Hanging objects may swing
- 5-5.9: Furniture moves, plastic may fall from the walls
- 7-7.9: Buildings displaced, cracks in earth, underground pipes may break
- 9 or over: Near total destruction, waves move through the visible eyes.
Measuring
The Magnitude Of Volcanic Eruptions:
- Volcanic Explosivity Index (VEI) is used to measure volcanic power.
- Measures the volume of ejection levels (duration of eruption)
- Humans have never experienced VEI 7 or 8
- VEI means the size of the volcano
- VEI 5-6 for Mount Pinatubo (largest in living memory)
- Most eruptions are small e.g Hawaii was VEI 1
Hazard
Profiles:
- A way of listing characteristics of a hazard or profile.
- Useful for insurance companies, government planners and aid charities
- Allows for easy comparison of different hazards on the same profile.
- Used to compare hazards with factors such as frequency.
What
They Include:
- Magnitude: How big the event is
- Speed of Onset: How fast the event is
- Area Extent: How big the area affected is
- Duration: How long was the event
- Frequency: How often the event happens
- Spatial Predictability: How easy it is to predict where the event happens
Frequency:
|
Frequent:
|
Rare:
|
|
Duration |
Long |
Short |
|
Area Extent |
Widespread |
Limited |
|
Magnitude |
High |
Low |
|
Speed of Onset |
Slow |
Fast |
|
Spatical
Predictability |
Random |
Regular/predictable |
|
Temporal Spacing
|
Regular |
Random |