Lesson 6 - Hazard Distribution: Earthquakes Flashcards
Where are the main earthquake zones found?
Along plate boundaries
Often in clusters
Where are roughly 70% of all earthquakes found?
The Pacific Ring of Fire
Which plate margins are the most powerful earthquakes typically associated with?
Destructive margins
What type of plate convergence is typically associated with earthquakes of magnitude 9Mw and above?
Oceanic - Continental convergence
Describe the pattern of tectonic activity revealed by the distribution of earthquakes
Earthquakes tend to occur at: The OFZ
The CFZ
Continental Interiors
What is the OFZ?
Oceanic Fracture Zone
Belt of earthquake activity through the oceans along mid-ocean ridges
Comes ashore in Africa, The Red Sea, Dead Sea Rift + California
What is the CFZ?
Belt of activity following the mountain ranges from Spain, via the Alps to the Middle East
+ The Himalayas to the East Indies and circumscribing the Pacific
What are the 3 ways plates can move in respect to one another?
Pull away
Slide past
Crunch into one another
Where do plates pull away from one another?
Divergent ‘spreading ridges’ in the oceans
What does this create?
Thin + dense oceanic crust
Describe the earthquakes that take place as a result (Divergence)
Frequent
Small
Low risk hazard due to geographical placement
Tend not to trigger tsunami
Where do plates slide past one another?
Convergent margins (E.g., San Andreas Fault)
What occurs as they slide past each other?
One slides underneath the other
Friction builds + is eventually released
Earthquakes produced
Describe the earthquakes that take place as a result
Very large
Highly damaging
Give an example of an earthquake produced by this plate movement (Convergence)
Japan 2011
Indonesia 2004
