anomaly: A brief and unexpected difference; something that is unusual and especially outside the normal range of what occurs.
ash: (in geology) Small, lightweight fragments of rock and glass spewed by volcanic eruptions.
chemical: A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.
core: Something — usually round-shaped — in the center of an object. (in geology) Earth’s innermost layer. Or, a long, tube-like sample drilled down into ice, soil or rock. Cores allow scientists to examine layers of sediment, dissolved chemicals, rock and fossils to see how the environment at one location changed through hundreds to thousands of years or more.
crater: A large, bowl-shaped cavity in the ground or on the surface of a planet or the moon. They are typically caused by an explosion or the impact of a meteorite or other celestial body. Such an impact is sometimes referred to as a cratering event.
crust: (in geology) Earth’s outermost surface, usually made from dense, solid rock (in planetary science) the outermost surface of rocky planets, dwarf planets and natural satellites.
crystal: (adj. crystalline) A solid consisting of a symmetrical, ordered, three-dimensional arrangement of atoms or molecules. It’s the organized structure taken by most minerals. Apatite, for example, forms six-sided crystals. The crystalline components of a rock are usually too small to be seen with the unaided eye.
dissolve: To turn a solid into a liquid and disperse it into that starting liquid. (For instance, sugar or salt crystals, which are solids, will dissolve into water. Now the crystals are gone and the solution is a fully dispersed mix of the liquid form of the sugar or salt in water.)
earthquake: A sudden and sometimes violent shaking of the ground, sometimes causing great destruction, as a result of movements within Earth’s crust or of volcanic action.
eruption: (in geoscience) The sudden bursting or spraying of hot material from deep inside a planet or moon and out through its surface. Volcanic eruptions on Earth usually send hot lava, hot gases or ash into the air and across surrounding land. In colder parts of the solar system, eruptions often involve liquid water spraying out through cracks in an icy crust. This happens on Enceladus, a moon of Saturn that is covered in ice.
force: Some outside influence that can change the motion of an object, hold objects close to one another, or produce motion or stress in a stationary object.
geology: The study of Earth’s physical structure and substance, its history and the processes that act on it. People who work in this field are known as geologists. Planetary geology is the science of studying the same things about other planets.
Hawaii: This central Pacific island chain became the 50th U.S. state on Aug. 21, 1959. Moving from west to east, its eight major islands are Niihau, Kauai, Oahu, Molokai, Lanai, Kahoolawe, Maui, and Hawaii (also known as the Big Island). The entire crescent-shaped island chain spans some 2,400 kilometers (1,500 miles). Each of the state’s islands was created from one or more volcanoes that long ago sprang up from the ocean floor. The chain sits some 3,857 kilometers (2,397 miles) west of San Francisco, Calif., and 8,516 kilometers east of Manila, the Philippines.
Iceland: A largely arctic nation in the North Atlantic, sitting between Greenland and the western edge of Northern Europe. Its volcanic island was settled between the late 800s and 1100 by immigrants from Norway and Celtic lands (ones governed by the Scots and Irish). It is currently home to roughly a third of a million people.
information: (as opposed to data) Facts provided or trends learned about something or someone, often as a result of studying data.
lava: Molten rock that comes up from the mantle, through Earth’s crust, and out of a volcano.
liquid: A material that flows freely but keeps a constant volume, like water or oil.
magma: The molten rock that resides under Earth’s crust. When it erupts from a volcano, this material is referred to as lava.
mantle: (in geology) The thick layer of the Earth beneath its outer crust. The mantle is semi-solid and generally divided into an upper and lower mantle.
molten: A word describing something that is melted, such as the liquid rock that makes up lava.
population: (in biology) A group of individuals (belonging to the same species) that lives in a given area.
prehistoric: An adjective for something that happened tens of thousands to millions of years ago, periods before people began deliberately recording events.
pressure: Force applied uniformly over a surface, measured as force per unit of area.
Queensland: One of the states that makes up the northeast corner of the country of Australia.
rift: (v.) to break or split apart, such as a friendship. (in geology) The separation of a span of Earth’s surface along a geologic fault as a result of plate tectonics. (n.) The term for such a break or split.
risk: The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)
solid: Firm and stable in shape; not liquid or gaseous.
sulfur dioxide: A compound made of sulfur and oxygen. It is one of the pollutants that can form when a fossil fuel is burned. It’s also a gas naturally emitted during volcanic eruptions. Its scientific symbol is SO2.
tectonic: Surface activity on a large rocky body (such as a planet or moon) as liquid rock flows up to the surface where it solidifies, then slowly drifts atop molten rock, carrying surface features with it.
volcano: A place on Earth’s crust that opens, allowing magma and gases to spew out from underground reservoirs of molten material. The magma rises through a system of pipes or channels, sometimes spending time in chambers where it bubbles with gas and undergoes chemical transformations. This plumbing system can become more complex over time. This can result in a change, over time, to the chemical composition of the lava as well. The surface around a volcano’s opening can grow into a mound or cone shape as successive eruptions send more lava onto the surface, where it cools into hard rock.
volcanologist: A scientist who works on the science of volcanos.