| A | B |
|---|
| crater | a bowl shaped depression that forms around the central vent at the top of the volcano |
| caldera | a larger crater that can form when the summit or side of a volcano collapses into the magma chamber during or after an eruption |
| cinder cone volcano | a steep-sided generally small volcano; made when cinders are ejected high into the air |
| composite volcano | a large volcano built by alternating layers of cinders and lava |
| shield volcano | a broad volcano with gently sloping sides built by non-explosive erruptions of lava |
| vent | opening in the top of the volcano through which the lava erupts |
| basaltic magma | low viscosity, non-explosive magma |
| andesitic magma | medium viscosity, medium explosive magma |
| rhyolitic magma | high viscosity, explosive magma |
| viscosity | the internal resistance to flow |
| lava | when magma reaches the surface |
| epicenter | the point on the Earth's surface directly above the focus of the earthquake |
| fault | the fracture or system of fractures along which movement occurs |
| focus | the point under the surface where the earthquake originates |
| primary wave | seismic waves that squeeze and pull the rock in the same direction that wave travels, causing the rock particles to move back and forth |
| secondary wave | seismic wave that causes rock particles to move at right angles to the direction of the wave |
| seismogram | instrument used to measure motion during an earthquake |
