| A | B |
|---|
| seismic waves | vibrations that travel through Earth and are caused by events like earthquakes or human-made blasts |
| seismologist | a scientist who detects and interprets seismic waves |
| disturbance | a movement that begins in one location and sets things in motion farther away. |
| P-waves | seismic waves that move with forward-and-backward motion. These waves are faster than S-waves and travel through solids and liquids |
| S-waves | seismic waves that move with a side-to-side motion, are slower than P-waves, and only travel through solids |
| crust | the outermost layer of Earth |
| mantle | the hot, flowing solid layer of Earth between the crust and the core |
| lithosphere | a layer of Earth that includes the crust and upper mantle |
| asthenosphere | the lower part of the upper mantle; lithospheric plates slide on this layer |
| core | the center of Earth; it is divided into inner and outer core |
| inner core | made mostly of iron, but is solid (from high pressure) |
| outer core | made mostly of iron, but is liquid. electric currents formed as liquid outer core moves, Earth's magnetic field |
