Term | Definition |
Earthquake | Energy waves passing through Earth, caused by a sudden shift along a fault line, or by volcanic activities. |
Crust | Outermost, rocky layer of Earth. |
Fault | Crack within Earth's rocky crust, where rocks move past each other. |
Mantle | A layer of Earth's surface, lying just below the crust and above the inner core. |
Lithosphere | Outermost layer of Earth's surface which is rocky and solid; includes the crust and the rigid part of the upper mantle. |
Lithospheric Plates | One of the pieces of Earth's rocky crust that rests and moves on the semi-liquid mantle. |
Seismologist | A person who studies earthquakes. |
Epicenter | The point on the surface directly above the focus. |
Focus | The point at which a rock under stress breaks and triggers an earthquake. |
Seismic Waves | Energy an earthquake releases. |
P-Waves | Causes buildings to contract and expand. |
S-Waves | Shakes buildings from side to side. |
Surface Waves | Shakes buildings violently. |
Seismograph | A device that records the ground movements caused by seismic waves. |
Richter Scale | Determines the magnitude by measuring seismic waves and fault movements. |
Mercalli Scale | Determines the rate of an earthquake by looking at the damage. |
Moment Magnitude Scale | Estimates a rating system. |
Liquefaction | The process in which an earthquake's violent shaking turns loose, soft soil into liquid mud. |
Tsunami | Large ocean waves usually caused by strong earthquakes below the ocean floor. |
Aftershock | An earthquake that occurs after a large earthquake centered in the same area. |
Base Isolators | Reduces the amount of energy that reaches a building during an earthquake. |
Shear Core Wall | Walls used to protect a building from falling over in an earthquake. |
Tension Ties | Tie the floor and ceiling of a building together. They scatter the damage, reducing the energy. |
Cross Braces | Placed between stories to stiffen a buildings frame and absorb the energy during an earthquake. |
Mass Damper | Absorb most of the energy from seismic waves. Reduce great damage. |
Flexible Pipes | Pipes that bend while earthquake energy passes through them. Prevent fires and floods. |
Shearing | Stress that pushes masses of rock in opposite directions in a sideways movement. |
Plateau | A land form that has high elevation and a more or less surface. |
Tension | Pulls on the crust, makes the middle of the rock thinner. |
Compression | Squeezes the rock and folds or breaks it. |
Normal Fault | The hanging wall slips downward below the footwall. |
Reverse Fault | The hanging wall slides up and over the footwall. |
Strike-Slip Fault | There is little up-or-down motion. |