| A | B |
|---|
| A vent from which magma, sold rock debris, and gas are erupted | Volcano |
| Ways to characterize magma | Range of compositions, ability to flow, high temperatures |
| 50% SiO2, very little dissolved gases | Basaltic |
| 60% SiO2, lots of dissolved gas | Andesitic |
| 70% SiO2, highest gas content | Rhyolitic |
| Depends on temperature and composition | Viscosity |
| more viscous, less able to flow | Rhyolitic |
| Medium | Andesitic |
| least viscous, greatest ability to flow | Basaltic |
| what happens when lava flows/becomes more viscous | Slows to a halt |
| what eruptions are determined by | How they erupt |
| Eruption with low viscosity magma and low-dissolved has levels; basaltic magma | Nonexplosive |
| Eruption that has a higher silica content, erupt at lower temperatures | Explosive |
| fragment of hot, shattered magma erupted | Pyroclasts |
| Basically ash | Tephra |
| Broad, roughly dome-shaped mound; formed by quiet, non-violent eruptions | Shield |
| Explosive eruptions, steep-sided, loose slopes | Cinder Cone |
| Quiet or violent, steep slopes, alternating layers of ash | Stratovolcano |
| The point a which a rock under stress breaks and triggers an earthquake | Focus |
| The point on the surface directly above the focus | Epicenter |
| Waves that carry the energy of an earthquake away from the focus | Seismic Waves |
| Compress/expand the ground; fastest, go through both solids and liquids | P-Wave |
| Vibrate from side to side/up and down | S-Wave |
| Move slowly, produce most severe ground movements | Surface Waves |
| Wave that causes the most damage | Surface Wave |
| Rates earthquake according to amount of damage | Mercalli |
| Rates earthquake by magnitude based on seismic waves | Richter |
| Estimates the total energy released | Moment Magnitudes |
| A device that records the ground movements caused by seismic waves | Seismograph |
