A ACTIVE - referring to a volcano that is presently erupting or has recently erupted ANDESITE -  a type of volcanic rock that has small crystals (sometimes too small to see), a gray color, lighter in color when compared to basalt (dark gray to black) ASH - small, dust-like particles emitted from a volcano ASH FALL - the emission of large amounts of ash from a volcano

B BANG - the sound of falling objects; in reference to sounds made by earthquakes BASALT - a dark colored igneous rock (dark color is caused by high amounts of iron and magnesium) with very small minerals, cooled relatively quick BOUNDARY - contact between two plates, can be converging, diverging, or transform; defined by an area that has active volcanoes and earthquakes; boundary refers to a large area, not just a single line

C CINDER - a very fine piece of partly burned pre-existing rock; usually red in color CINDER CONE - volcano made of cinders with steep sides COMPOSITE - volcano that has layers of igneous rocks (ash and lava), sides are not as steep as a cinder cone CONE - the general shape of volcanoes; looking like an upside down, fat ice cream cone CONTINENT - a large land mass that is above water, usually made of less dense material compared to the surface of the oceanic crust CONTINENTAL DRIFT - the movements of the continents over time; a historical term because the continents and oceans move together CONTRACTING - becoming smaller CONVECTION - movement in which a warmer substance rises because it is less dense than the surrounding cooler substances, as it rises it because cooler, hence more dense, and then sinks causing a cyclic movement CONVERGE - the movement toward each other; coming toward or to the same point; referring to large segments of the Earth's crust called plates CRASH - the sound of glass breaking during an earthquake CRATER - the concave top of a volcano, where the eruption is taking or took place CREST - the highest portion of an energy wave; the highest point CRUST - the outermost shell of the earth, about 71 km

D DAMAGE - harm to structures, animals, or humans during earthquakes and/or volcanoes DEBRIS - different sized rocks that have accumulated as a group; pile of rocks DIATOMITE - a very light, white rock that contains diatoms (one-celled plants), radiolarians (protozoa), and clay particles DISASTER - an event that causes much damage or harm DIVERGING - the movement of plates away from each other; going in different directions from a common point DOME - a volcanic shape; looking like an upside down soup dish DORMANT - a volcano that is temporarily inactive or "sleeping" DRIFT - referring to the movement of continents over time DRILL - to make a hole

E EARTH - one of the planets that evolve around the sun in the solar system EARTHQUAKE - a shaking or trembling of the earth EARTHQUAKE "EVENT" - the recording of an earthquake ENERGY - power or force that has the ability to do work; referring to an earthquake or volcano as the amount of energy liberated ENERGY WAVE - referring to an earthquake, the power released and moved through substances in a form described as wave motion EPICENTER - a point on the earth's surface that reflects where an earthquake originated (see focus) ERUPT - to force out or release suddenly and often violently ERUPTION - the process of erupting EVACUATION - to withdraw from an area EXPANDING - becoming larger EXTINCT - referring to a non-active volcano for a long time; will not erupt again

F FAULT - a fracture in the earth's crust where rocks are moving against each other FOCUS - a point inside of the earth where an earthquake originates FREQUENCY - the number of times that a complete wavelength repeats itself

G GAS - a substance with an expandable molecular structure that is often emitted from a volcano during an  eruption GEOLOGIST - a career that emphasizes any part of studying the Earth [paleontologist: studying fossils); seismologist (studying earthquakes); volcanologist (studying volcanoes), etc] GLASSY - referring to the texture of a rock or mineral when looked at through a broken edge, resembles broken glass GRANITE - a slowly cooled igneous rock that usually has many large, light colored minerals; usually has white, pinkish, and black minerals GROW - referring to volcanoes as they increase in size

H HAZARD-source of danger HOLE - referring to structures found on volcanic rocks that were formed as trapped gases within the lava escaped as the rock was forming, leaving behind depressions or indentations HORIZONTAL - level, parallel with the surface of the earth

I INNER CORE - the Earth's innermost shell, starting at 5000 km and ending 6371 km beneath the surface of the earth INTENSITY - a measure of the effects of an earthquake as estimated from the damage done; Mercalli scale is used IGNEOUS - referring to rocks that were at one time melted and cooled

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LAVA - molten material that is erupted from a volcano LAVA FLOW - lava that moves like a viscous liquid LANDSLIDE - unstable earth that flows downward LARGE EARTHQUAKE - an earthquake that causes damage, usually over a 7.0 on the Richter Scale LIQUEFACTION - to become liquid (usually refers to soil that "settles" during an earthquake LIQUID - a substance that flows

M MAGMA - a molten fluid which may consolidate into rock MAGNITUDE - a measure of the amount of energy set free in an earthquake; size or largeness of an earthquake, Richter Scale is used MANTLE - the part of the earth's interior between the crust and the outer core, roughly 71-2900 km beneath the earth's surface MERCALLI SCALE - a system for measuring the intensity of an earthquake in terms of the amount of damage caused MINERALS - naturally occurring, inorganic, crystalline substances that make up rocks MODERATE EARTHQUAKE - an earthquake that is neither weak nor strong MOUNTAIN - a large structure whose peaks lie above sea level MOUNTAIN BUILDING - creating mountain through the process of plate tectonics MOVEMENT - referring to the slow crustal displacement MUD FLOW - the movement, due to gravity, of very fine particles of earth that are mixed with water MUDSLIDE - the massive downward movement of mud MYTH - a story that serves to unfold part of the world view of people or explain a practice, belief, or natural phenomenon

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O OBSIDIAN - an igneous rock that cooled very quickly, therefore not allowing minerals to form OUTER CORE - the layer of the Earth between 2900 and 5000 km beneath the surface

P PLATE - a large piece of earth and ocean area that comprises the Earth's crust PLATE TECTONICS - the study of the movement of the Earth's crust due mainly to forces in the crust and upper mantle of the Earth's interior PRESSURE - a force exerted or extended over an area PRIMARY (P) WAVE - push-pull wave; first wave movement to be recorded on a seismogram after an earthquake PUMICE - a light colored, glassy, porous rocks that was formed by the passing of gases through molten lava PYROCLASTIC - composed of pieces of volcanic material

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R RICHTER SCALE - a system used to measure the magnitude of an earthquake by using mathematical analysis RING OF FIRE - the concentration of volcanoes along the rim of the Pacific Ocean ROCK - a hard substance that comes from the Earth's interior either by erosion (sedimentary), cooled molten materials (igneous), or changed under pressure and temperature (metamorphic) RUMBLE - referring to the sounds of an earthquake; a natural sound that the earth makes when it shakes

S SAFETY - keeping oneself free from harm SCORIA - pieces of rough, porous lava that have been erupted from a volcano; many times comes in a red color SEA COOKIE - a relative of the sand dollar (echinoderm), that lives in the sandy-mud offshore SEA URCHIN - a relative of the sand dollar that lives on rocks and ocean bottoms SECONDARY (S) WAVES - shear wave; the second wave to be recorded after an earthquake SEISMOGRAM - a pictorial representation of seismic waves SEISMOGRAPH - a machine that records earthquake wave energy SEISMIC WAVE - a wave caused by the release of energy during an earthquake SEISMICITY - having to do with earthquakes SHAKE - referring to the movement that is felt when an earthquake occurs SHAPE - the outlines of an object SHIELD - a volcano that has a low dome shape STRESS - a force applied to an area STRONG - referring to an earthquake of great intensity STRUCTURAL DAMAGE - referring to the damage of a building caused by the shaking of an earthquake; can include cracks, unstable bricks, and general weaknesses in the structures in a building

T THRUST - the movement of one layer over another; referring to plates that converge TIME - a measured period during which an action, process, or condition exists or continues; geologic time  refers to a vast amount of time TRANSFORM - a fault that has a slip/slide motion TROUGH - the lowest portion of a wave TSUNAMI - water waves created by a large earthquake (not a tidal wave)

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V VALLEY - a depression of low area usually between two mountain ranges VENT - the opening of a volcano where lava is expelled VERTICAL - upright; 90 degrees to the plane of the horizon (the line where the earth and the sky appear to meet ) VISCOUS - a liquid that moves slowly VOLCANO - formed when hot, melted rock erupts and builds a mountain-like structure on the surface of the Earth VOLCANIC BOMBS - rocks and fragmented material blown out when a volcano erupts VOLCANIC HAZARD - danger caused or imposed by a volcano VOLCANIC MUD - the mixture of volcanic ash with water

W WAVE - the undulation of a substance as energy passes through a substance WAVE FREQUENCY - change of the waveheight WAVE SPEED - the speed of a wave WAVELENGTH - the distance of a wave from crest to crest WAVEHEIGHT - the height of a wave (measure of the distance between a crest and a trough divided by two) WEAK - referring to a very mild shaking during an earthquake; in most cases not even felt

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