Glossary

Fault

A fault is a break in rock along which two blocks have moved. There are three main types. A normal fault forms when the crust stretches, a reverse fault when it is compressed, and a strike-slip fault when the blocks slide horizontally.

An active fault can stay locked for a long time while building up energy, then rupture suddenly. That rupture is what produces an earthquake. The map shows more than 9,000 active faults, visible when zoomed in.

Examples on the Map

• Active Faults
• Main Frontal Thrust (Himalaya)
• Wasatch Fault

Other Definitions

• Tectonic Plate
• Subduction
• Mid-Ocean Ridge
• Transform Fault
• Earthquake, Epicentre and Hypocentre
• Magnitude
• Intensity (Mercalli Scale)
• Aftershock
• Tsunami
• Active Volcano
• Stratovolcano
• Shield Volcano
• Caldera
• Volcanic Explosivity Index (VEI)
• Pyroclastic Flow
• Lahar
• Hotspot
• Tropical Cyclone, Hurricane, Typhoon
• Saffir-Simpson Scale
• Aurora and Kp Index