Glossary beginning with E

Volcano Term Definitions

Echelonsearch for term

Set of geologic features that are in an overlapping or a staggered arrangement (e.g., faults). Each is relatively short, but collectively they form a linear zone in which the strike of the individual features is oblique to that of the zone as a whole.

Ejectasearch for term

Material that is thrown out by a volcano, including pyroclastic material (tephra) and lava bombs.

Eruptionsearch for term

The process by which solid, liquid, and gaseous materials are ejected into the earth's atmosphere and onto the earth's surface by volcanic activity. Eruptions range from the quiet overflow of liquid rock to the tremendously violent expulsion of pyroclastics.

Eruption Cloudsearch for term

The column of gases, ash, and larger rock fragments rising from a crater or other vent. If it is of sufficient volume and velocity, this gaseous column may reach many miles into the stratosphere, where high winds will carry it long distances.

Eruptive Ventsearch for term

The opening through which volcanic material is emitted.

Evacuatesearch for term

Temporarily move people away from possible danger.

Extinctsearch for term

A volcano that is not presently erupting and is not likely to do so for a very long time in the future.

Extrusionsearch for term

The emission of magmatic material at the earth's surface. Also, the structure or form produced by the process (e.g., a lava flow, volcanic dome, or certain pyroclastic rocks).