Sources of Earthquakes

Earthquakes commonly occur at plate boundaries.

Convergent Plate Boundaries

• Subduction Zones
• Continental-Continental Collision Zones
• the largest earthquakes occur in these areas!

Faulting

• Strike-slip
• Normal
• Reverse/Thrust

Divergent Plate Boundaries

In Western America, these areas are close to densely populated areas, putting millions of people at risk:

Convergent Plate Boundaries

• Cascadia Subduction Zone
• Middle America Trench

Faulting

• San Andreas Fault Zone

Divergent Plate Boundaries

• East Pacific Rise

The USGS National Seismic Hazard Map shows where in the US the greatest risk of earthquakes are found.

1. West Coast
2. Alaska (Aleutian islands)
3. Hawaii
4. Yellowstone
5. New Madrid Seismic Zone
6. Charleston, South Carolina