1.5B - Hazard Profiles
Comparing the characteristics of earthquakes, volcanoes and tsunamis (magnitude, speed of onset and areal extent, duration, frequency and spatial predictability) through hazard profiles.
Tectonic events can be compared using hazard profiles. These allow a better understanding of the nature of hazards, and therefore risks associated which each. For example, there may be a continuous line ranging from least to greatest (for example, short to long with duration), with each hazard event located on this line (in relation to their duration in this example.) It gives more information than just ranking them, since it shows the difference between each event, and can be used to compare multiple aspects of different hazards (or different types of the same hazard, e.g. volcano).
Hazards with the following characteristics present the highest risk:
- high magnitude, low frequency events - these are the least 'expected' as, by definition, they are unlikely to have occurred in living memory
- rapid onset events with low spatial predictability - they could occur in numerous places and without warning
- regional areal extent - affecting large numbers of people in a wide range of locations
Basaltic shield eruption
Magnitude: small
Speed of onset: fairly slow
Areal extent: local
Duration: fairly long
Frequency: quite high
Spatial predictability: fairly precise
Andesitic composite cone eruption
Magnitude: almost middling
Speed: middling
Areal extent: closer to local than regional
Duration: medium
Frequency: fairly low
Spacial predictability: fairly precise (but less so than basaltic shield)
Subduction zone earthquake
Magnitude: more than medium
Speed: very rapid
Size: closer to regional than local
Duration: shortest
Frequency: closer to low than high
Spatial predictability: fairly random
Tsunami
Magnitude: largest
Speed of onset: rapid
Areal extent: largest
Duration: quite short
Frequency: high
Spatial predictability: highest
See how much easier and more efficient the profile makes it!
Arguably, major earthquakes at subduction zones and collision zones are the most dangerous tectonic hazards. They can have magnitudes of 8-9 MMS, cannot be predicted and could occur along any of tens of thousands of kilometres of plate margin, instantaneously.