| A | B |
|---|
| foreshock | a small burst of shaking that occurs before a large earthquake. |
| aftershock | a small tremor that follows an earthquake. |
| earthquake | the movement of Earth’s crust resulting from the release of built up potential energy between two stuck lithospheric plates. |
| focus | the point below Earth’s surface where a rock breaks or slips and causes an earthquake. |
| fault | a region on Earth’s surface that is broken and where movement occurs. |
| epicenter | a point on Earth’s surface right above the focus of an earthquake. |
| seismograph | an instrument that measures and records |
| body waves | seismic waves that travel through the interior of Earth. |
| survace waves | seismic waves that reach and travel along Earth’s surface. |
| Richter scale | a scale that ranks earthquakes according to the size of the seismic waves. |
| Moment Magnitude scale | a scale that rates the total energy released by earthquakes. |
| Modified Mercalli scale | a scale that rates the damage experienced by buildings, the ground, and people during an |
| volcano | an erupting vent through which molten rock and |
| magma | underground melted rock. |
| magma chamber | a location where magma collects inside Earth. |
| lava | magma that has reached and cooled on Earth’s surface. |
| viscosity | the property of a fluid that resists the force tending to cause the fluid to flow. |
| silica | the amount controls the viscosity, or the resistance of a substance to flow. The higher the level, the more viscous the magma is; therefore, the volcano eruption is greater and more explosive. |
| shield volcano | a flat and wide volcano that has low silica magma |
| cinder cone | a volcano that has low silica magma and lava with |
| composite volcano | a tall, explosive, coneshaped volcano formed by layers of silicarich lava and ash. |
| Ring of Fire | a region of Earth’s plate boundaries where oceanic |
