Faults and Motion
This fault type occurs at transform boundaries with horizontal sliding.
Strike-slip fault
The fastest seismic wave that travels through solids, liquids, and gases.
P-wave (primary wave)
The record produced by a seismograph.
Seismogram
This type of sediment amplifies seismic vibrations
Soft
Smaller quakes that follow the main event.
Aftershocks
Gradual displacement along a fault without major quakes.
Fault creep
These waves travel just below the surface and cause the most property damage.
Surface waves
A base-10 logarithmic scale that measures wave amplitude but fails for very large quakes.
Richter scale
When soft material turns into a mobile fluid during shaking.
Liquefaction
The study of ancient earthquake timing and location.
Paleoseismology
Thrust fault at a subduction zone that produces Earth’s largest earthquakes.
Megathrust fault
Body waves that move perpendicular to their direction of travel and only through solids.
Megathrust fault
Scale using Roman numerals and standardized damage observations.
Modified Mercalli Intensity Scale
Enormous ocean waves caused by seafloor displacement.
Tsunamis
Areas along faults without quakes for centuries, likely due soon.
Seismic gaps
Harry Fielding Reid proposed this theory after the 1906 San Francisco quake showed 9.7 m of plate slip.
Elastic rebound theory
Seismic waves do this when they change direction passing between layers.
Refraction
Magnitude type calculated from fault slippage and rock strength.
Moment magnitude
The first sign of a tsunami is this
Receding tide; its trough
Seismic waves are used like this medical imaging technique to study Earth’s layers.
Ultrasound
Reid compared Earth’s crust deforming to this object snapping under stress.
Stick
The instrument with a suspended weight and rotating drum attached to bedrock.
Seismograph (or seismometer)
Online surveys create this kind of intensity map using public reports.
Community Internet Intensity Map
Liquefaction can eject material, forming these
Sand volcanoes
Most earthquakes occur along these two major global belts (name one).
Circum-Pacific belt; Alpine-Himalayan belt