Vulcanicity- Key terms Flashcards Preview

Physical Geography > Vulcanicity- Key terms > Flashcards

Flashcards in Vulcanicity- Key terms Deck (19)
Loading flashcards...
1

What is magma?

Magma is molten rock found beneath the Earth's surface

2

What is lava?

Lava is the term used for molten rock once it has been ejected at the surface

3

What are volcanic bombs??

Volcanic bombs are crusted over deposits of ash which are ejected during volcanic eruptions

4

What is tephra?

Tephra is airborne ash and dust ejected during volcanic eruptions

5

What is a conical hill?

A conical hill is a rounded mountain shape, the form of which volcanoes most commonly take

6

What is an active volcano?

Active volcanoes are volcanoes that have erupted in living memory. They can be either very or intermittently active

7

What is a dormant volcano?

Dormant volcanoes are volcanoes that have erupted within historical record

8

What is an extinct volcano?

Extinct volcanoes are volcanoes that won't erupt again as they haven't erupted in the last 25,000 years

9

What is an intrusive landform?

An intrusive landform is what is formed when magma is injected into the crust but does not reach the surface

10

What is an extrusive landform?

Extrusive landforms are formed when the magma does reach the surface

11

What are gaseous emissions?

Gaseous emissions are emissions released from a volcanic eruption; they are dominated by steam but also highly dangerous gases such as hydrogen sulphide and carbon monoxide

12

What is pyroclastic material?

Pyroclastic material is a wide range of volcanic fragments from fine grained ash and lapili to volcanic bombs. Characteristic of more gaseous phases of eruption.

13

What are lahars?

Lahars are when ash is spread and mixes with rain or meltwater, forming fast moving mud flows

14

What is lapili?

Lapili is tephra in it's finest form of hairlike trails

15

What is basaltic lava?

Basaltic lava is lava formed from the upward movement of magma at constructive margins e.g. ridges and hot spots, low in silica so more fluid and allows gas bubbles to enter, preventing sudden explosions

16

What is andesitic lava?

Andesitic lava is formed at destructive plate margins due to the destruction of the crust. Silica rich and so very viscous. Often solidifies before reaching the surface, building pressure which results in a violent explosion. Gases can't escape so eruptions are explosive.

17

What is rhyolithic lava?

Rhyolithic lava is formed at destructive and collision margins and has the same characteristics as andesitic.

18

What are volcanoes?

Volcanoes are openings in the Earth's crust through which lava, ash and gases erupt, marking the presence of magma

19

What is the VEI

The Volcanic Explosive Index; a scale which uses several volcanic characteristics to judge the size of an eruption