| A | B |
|---|
| lithosphere | crust and upper mantle |
| plates | large pieces of the lithosphere that float on melted rock in the mantle |
| Theory of plate techtonics | The idea that the earth's crust is made up of moving plates |
| plate boundaries | places where tectonic plates meet |
| earthquake | the release of energy resulting in vibrations of the surface of the earth |
| faults | breaks in the earth's surface |
| reverse fault | rocks push together until they force a section of the rock upward |
| normal fault | rocks move apart, molten rock may fill the gap |
| strike-slip fault | rocks move horizontally past each other |
| focus | the beginning point of an earthquake (under the ground) |
| seismic waves | vibrations of an earthquake |
| epicenter | the point on the surface of the earth directly above the focus |
| body waves | seismic waves beneath the surface of the earth |
| P waves | fastest moving body waves, travel in a push and pull motion |
| S waves | slower body waves, move in an up-and-down zigzag pattern |
| L waves | land waves |
| Love waves | fastest moving land waves, move in a zigzag pattern |
| Rayleigh waves | land waves that move along the ground in a rolling motion |
| seismologists | scientists that study the movement of the earth |
| seismograph | an instrument used to detect, time, and measure the movements of the earth |
| magnitude | strength of the seismic waves of an earthquake |
| Richter scale | a decimal scale to measure the magnitude of an earthquake, each decimal number is 10x greater than the previous one |
| Mercalli scale | based on the amount of destruction that an earthquake causes |
| tsunami | giant waves caused by an earthquake, volcano, or mudslide under or near the ocean |
| magma | molten rock |
| volcano | a crack in the earth's surface that allows magma and gases to come to the surface |
| volcanologist | scientist that study volcanoes |
| magma chamber | pocket of molten rock |
| lava | magma above the surface of the earth |
| vent | opening at the top of a volcano |
| crater | the bowl shape at the top of a main vent |
| flank eruption | an eruption that flows through side vents |
| ash | jagged bits of crushed rock |
| cone | funnel shaped mound |
| Ring of Fire | an area of active volcanoes around the Pacific Ocean |
| submarine eruption | underwater volcano |
| hot spot | place where a pool of intensely hot magma rises toward the surface |
| shield volcano | volcano with gradually sloping sides, formed by a continual flow of lava |
| cinder cone volcano | cone shaped volcano with one main vent, explosive eruption |
| composite cone volcano | large cone shaped volcano with steep sides made of layers of hardened lava and tephra |
| tephra | mixture of cinders, ash, and rock |
| cinder | bits of lava expelled by a volcano |
| active volcano | volcano that has erupted at some point during a recorded time period and is expected to erupt again |
| dormant volcano | volcano that has erupted during the distant past but is currently inactive and not expected to erupt in the future |
| extinct volcano | volcano with no recorded eruption, not expected to erupt again |
| Hawaiian eruption | volcano with runny lava and little or no cinder, ash, or steam |
| Strombolian eruption | volcano with a fountain of lava that runs down the side |
| Vulcanian eruption | violent eruption that sends lava, ash, cinders, and gas into the air |
| Pelean eruption | violent eruption that includes pyroclastic flow |
| pyroclastic flow | avalance of red-hot dust and gases |
| Plinian eruption | the most violent eruption - spews out lava, blows gases, ash and debris high into the atmosphere |
| vog | volcanic fog |
| debris flow | mountain collapses and mud and rock fragments surge down the mountain |
| igneous rock | rock formed by volcanoes |
| pumice | lightweight igneous rock |
| obsidian | hard, glassy igneous rock |
| granite | rock formed as magma cools underground |
| hot spring | a pool of ground water heated by magma |
| geyser | a hot spring that periodically blows steam and hot water into the air |
| mud pot | a hot spring that contains more mud than water |
