volcano icon Types of Volcanoes & Eruptions

Types of volcanoes

Volcanoes can be classified by type. The style of eruption, structure and composition determine a volcano's type.

  • Shield volcanoes
shield volcano

Shield volcanoes, such as Ambrym and Ambae, are characterised by a broad, flat and convex shape with a summit calderas. The vents are mostly localized at the summit and on the rift zones. Eruption frequency is variable, decade to century. The eruptions consist of fluid lava flows, weak fountaining explosions, summit explosions and ash fall.

  • Caldera volcanoes
Caldera volcano

Caldera volcanoes, such as Ambrym, AmbaeGaua and Yasur are characterized by a central or summit location with the predictable eruption location and often have a small volcanoes cone and lakes inside them. The caldera forming are from very large eruptions. Eruptions are rare. Eruption frequency is from 1000's years.

  • Cone volcanoes
Cone volcano

Cone volcanoes, such as Lopevi, Gaua, Ambrym and Yasur are characterized by a central or summit vent with the predictable eruption location, steep-sided cone shape and multiple vents can build small volcano complexes over extended area. Eruption frequency is between 10's - 100's years. Eruptions are explosive often powerful and consist of lava domes, lava flows, mud flows, floods and infrequent major collapses.

  • Scoria cones and Maars
Maar

Scoria cones and Maars (mostly along rifts) are characterized by nunerous small volcanoes over extended area with random eruption location such as present in Vanuatu along the rifts of  Ambrym and Ambae. There are variety of eruption style, dry creates cones and wet creates maars. Eruption frequency 100's to 1000's years.

 

 
Types of eruptions
 
Multiples types of eruption can occur at each of Vanuatu's volcanoes - the eruption type can vary minute to minute.
The style of eruption depends on a number of factors, including the magma chemistry and content, temperature,
viscosity, volume and how much water and gas is in it, the presence of groundwater, and the plumbing of the volcano.
Vanuatu's volcanoes have different characteristics based on their style of eruption, geography, geology, structure,
composition and historical activity. Many of them have explosive activity and eject mostly ash or tephra, volcanic
gases and lava. For information on volcanic hazards which can be produced by our volcanoes, click here.
 
  •  Strombolian and Hawaiian eruptions
 These are least violent types of explosive eruptions. Hawaiians have fire fountains and lava flows,
 whereas Strombolian eruptions have explosions causing a lava fragments.
 
  • Vulcanian eruptions
 These eruptions are small to moderate explosive eruptions, lasting seconds to minutes.
Ash column can be up to 20 km in height, and lava blocks and bombs may ejected from the vent.
 
  • Subplinian and plinian eruptions
Eruptions with a high rate of magma discharge, sustained for minutes to hours.
They form a tall eruption column of a mixture of gas and rocks particules, and can cause wide dispersion of ash.
 
  • Phreatic eruptions
An eruption driven by the heat from magma interacting with water.
The water can be groundwater, hydrothermal systems, surface runoff, a lake or the sea.
This type of eruption pulverise surrounding rocks and can produce ash, but do not include new magma.
 
  • Phreatomagmatic eruptions
 An eruption resulting from the interaction of new magama or lava with water and can be very explosive.
The water can be from groundwater, hydrothermal systems, surface runoff, a lake or the sea.