| A | B |
|---|
| viscosity | the internal resistence to flow |
| basaltic magma | forms when rocks in the upper mantle melt |
| andesitic magma | found along continental margins where oceanic crust is subducted into Earth's mantle |
| Rhyolitic magma | forms when molten material rises and mixes with the overlying silica- and water-rich continental crust |
| vent | where lava erupts through an opening in the crust |
| crater | located at the top of a volcano, around the vent |
| calderas | can be up to 50km in diameter, can form when the summit or the side of a volcano collapses into the magma chamber that once fueled the volcano |
| shield volcano | mountain with broad, gently sloping sides and a nearly circular base |
| cinder-cone volcano | forms when material ejected high into the air falls back to Earth and piles up around the vent |
| composite volcano | forms when layers of volcanic fragments alternate with lava |
| tephra | rock fragments thrown into thte air during a volcanic eruption |
| pyroclastic flow | rapidly moving volcanic material |
| hot spots | unusually hot regions of Earth's mantle where high-temperature plumes of mantle material rise toward the surface |
| stress | the forces per unit area acting on a material |
| strain | the deformation of materials in response to stress |
| fault | the resulting fracture or system of fractures, along which movement flows |
| reverse faults | fractures the form as a result of horizontal compression |
| normal faults | fractures caused by horizontal tension |
| strike-slip faults | fractures caused by horizontal shear |
| P-waves | squeeze and pull rocks in the same direction along which the waves are traveling |
| S-waves | cause rocks to move at right angles in relation to the direction of the waves |
| surface waves | move in two directions as they pass through rock |
| focus | the point where the earthquake originates |
| epicenter | the point on Earth's surface directly above the focus |
| seismometers | vibrations from earthquakes are detected and recorded by sensitive instruments |
| seismogram | the recors produced by a seismogram |
| magnitude | the amount of energy released during as earthquake |
| Richter Scale | how an earthquake is rated based on the size os the largest seismic waves |
| Mercalli Scale | rates the types of damage and other effects of an earthquake as noted by observers during and after its occurence |
| tsunami | large ocean wave generated by vertical motions of the seafloor during an earthquake |
