Saturday, April 3, 2021

Terms to Remember on Module: Effects of Volcanoes

Active volcano A volcano that has erupted within historic times such that

accounts of its eruption have been documented by man.

Mayon Volcano - Albay, Philippines 

Airfall deposition Composed of separate materials varying in size from ashes

to small boulders.

Ashfall A heavy downfall of volcanic ashes that can cause harm to human

beings, animals, crops, machinery, and buildings.

Basalt lava The accretion of thousands of highly fluid lava flows that spread

widely over great distances and then cool as thin, gently dipping sheets.

Basalt Lava (Image from http://meteorite-identification.com)

Base surge A rapidly moving mixture of volcanic debris and steam.

Caldera A depression formed by a collapsed volcano.

Laguna de Quiltoa, a caldera in Ecuador

Cinder cone The simplest type of volcano.

Cinder cone volcano

Conduit A volcanic plug.

Coulee A short, steep-sided lava flow.

Coulee
(Image from http://sci.sdsu.edu)

Crater A funnel-shaped depression opening upward near the summit of a

volcano from which materials such as ashes and lava are ejected.

Dome Formed by relatively small, bulbous masses of lava too viscous to flow

any great distance, consequently, on extrusion, the lava piles over and around

its vent.

Fissure A dike.

Inactive volcano A volcano that has not erupted within historic times and

whose form is beginning to change because of weathering and erosion.

Lahar Commonly called a mudflow, a flowing mixture of volcanic

materials and water.

Lahar

Lava The magma that has erupted from a volcano or fissure and flowed on to

the earth’s surface or the ocean floor.

Maar A shallow to deep circular depression of volcanic origin.

Maar

Permanent danger zone An area within a 4- to 6-km radius from the summit

of a volcano.

Phreatic explosion An explosion that has plumes reaching heights of 5000

to 20000 m.

Taal Volcano - Phreatic Explosion/Eruption

Pipe A tunnel connecting the crater and the molten materials inside the earth

through which the ejected materials pass.

Plinian eruption Considered to be one of the most dangerous eruptions

because it is characterized by extremely viscous lava and the formation of

glowing clouds.

Plinian eruption of Redoubt Volcano

Pyroclastic flow Extremely hot, often incandescent and turbulent blast of

volcanic fragments and hot gases that sweeps downslope close to the ground at

hurricane speed of up to 100 kph.

Pyroclastic flow deposit Composed of separate materials varying in size

from ashes to small boulders.

Rift zone A vent along a fracture that develops on the flank of the cone.

Secondary explosion A steam explosion that occurs when water seeps into

the still-hot pyroclastic flow and ejects ashes and ballistic fragments to as high

as hundreds to thousands of meters from the source.

Shield volcano A volcano built almost entirely of fluid lava flows.

Stratovolcano Also called a composite volcano.

Tuff Porous rock.

Tuff

Volcano A hill or mountain composed wholly or in part of ejected materials

usually molten or hot rocks and steam issues.

Vulcanian Explosive in nature.

No comments: