Acoustic: Pertaining to sound.
Bathymetric map: A chart of ocean floor depths, similar to topographic maps on land.
Caldera: A depression formed at the summit of a volcano caused by collapse when magma is removed from the reservoir below.
Chemosynthesis: The process by which microbes mediate chemical reactions to produce into energy. In contrast to photosynthesis, because chemosynthesis does not require sunlight.
Contour profile: A cross-section of topography along a given line.
Degree: A unit of angular distance. There are 360 degrees in a circle (as on a compass).
Deposit feeder: Animals that consume small pieces of plant and animal material that settle to the ocean floor from the water column.
Epicenter: The point on the Earth's surface from which earthquake waves seem to radiate, located directly above the true center of the earthquake at depth.
Earthquake swarm: A sequence of many small earthquakes (10's to 1000's), all of similar size (<M4) and within a relatively short period of time (hours to weeks). Earthquake swarms are often recorded during volcanic activity.
Hydrophone: An instrument used to record sound under water.
Hydrothermal vent: A hot spring on the seafloor.
Latitude: Angular distance on the Earth's surface measured north or south of the Equator.
Lava: Molten rock after it has erupted from a volcano onto the Earth's surface.
Longitude: Angular distance on the surface of the Earth measured east or west from the prime meridian at Greenwich, England.
Magma: Molten rock that is underground before it has erupted onto the Earth's surface.
Microbes: Single-celled living organisms, such as bacteria and archaea.
Mid-ocean ridge: A type of tectonic plate boundary where two tectonic plates are moving apart (also called a "spreading center"). Volcanic activity creates a ridge at the boundary.
Minute: A unit of angular distance that is one-sixtieth of a degree.
Observatory: A site for long-term scientific observations.
ROPOS: The name of the remotely operated vehicle usually used at NeMO. ROPOS stands for Remotely Operated Platform for Ocean Science.
Rumbleometer: (pronounced rum-ble-om'-i-ter) A seafloor instrument that measures temperature and pressure (among other things) to help monitor submarine volcanoes.
Seamount: An undersea mountain rising over 1000 meters above the surrounding seafloor.
Seismometer: An instrument that detects ground movement from earthquakes.
Sessile: Permanently attached at the base; fixed in one place and unable to move around.
Spreading center: See mid-ocean ridge
Subduction zone:
A type of tectonic plate boundary where two tectonic plates are converging (moving toward each other) and one plate is forced under the other.
Sulfide chimney: Formations made of sulfide minerals deposited directly from hydrothermal vent fluid at high-temperature seafloor hot springs.
Symbiotic: The relationship of different organisms in a close association that is mutually beneficial. Many vent animals have symbiotic relationships with chemosynthetic microbes.
Tectonic plates: Large intact pieces of the Earth's outer rocky layer that move in relation to one another. Most of the Earth's earthquakes and volcanoes are located near plate boundaries.
Transform fault: A type of tectonic plate boundary where one plate slides past another.
Triangulation: Method of finding a position with distances or angles from known points.

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