UNIT

11The evolution of landforms

Biology and Geology 4. Secondary Education

TYPES OF ERUPTIONS AND VOLCANIC EDIFICES

UNIT

11Types of eruptions and volcanic edifices

TYPES OF VOLCANOES

WITH HAWAIIAN TYPE ERUPTIONS

WITH PELEAN TYPE ERUPTIONS

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WITH STROMBOLIAN TYPE ERUPTIONS

Biology and Geology 4. Secondary Education

UNIT

11Types of eruptions and volcanic edifices

• These volcanoes generally expel highly liquid lava that flows slowly.

• They are usually less hazardous volcanoes, as the eruptions are not very explosive, except in cases where lava fields are very fast moving or when toxic gases are released.

• The edifices of these volcanoes are shaped like a shield, with gentle slopes, and they cover enormous areas, due to the way the lava is deposited on their slopes.

• The Hawaiian Islands are an example of this type of volcano.

Hawaiian type volcanic eruptions

Biology and Geology 4. Secondary Education

UNIT

11Types of eruptions and volcanic edifices

• These volcanoes expel denser magma than the Hawaiian type, so the magma solidifies more easily.

• They expel large amounts of toxic gases, red-hot pyroclasts and ashes that can bury entire villages, as well as pyroclastic flows that can scorch everything in their path. They are therefore highly dangerous volcanoes.

• Their edifices are shaped like a stratovolcano; in other words, they are tall and conical. Sometimes, during the more violent eruptions, the cone collapses, and over time and after other less violent eruptions, it rebuilds itself.

• Mount Vesuvius and Krakatoa are examples of volcanoes that produce such eruptions.

Strombolian type volcanic eruptions

Biology and Geology 4. Secondary Education

UNIT

11Types of eruptions and volcanic edifices

• These volcanoes expel very dense magma which solidifies in the crater, obstructing the expulsion of gases. The pressure accumulates and generates violent explosions.

• The explosions expel pyroclastic flows of a mixture of gases and red-hot ashes which travel down the slopes of the volcanoes at great speed.

• Their edifices are shaped similarly to the Hawaiian type.

• Mount Pelée, a volcano on the island of Martinique, produces this type of eruption.

Pelean type volcanic eruptions

Biology and Geology 4. Secondary Education