What makes shield volcanoes

There are two main types of volcano - composite and shield. The two types of volcano form in different places and have very different characteristics. Composite volcanoes are found on destructive plate margins , where the oceanic crust sinks beneath the continental crust.

Composite volcanoes have the following characteristics:. Notice that the caldera is composed of numerous smaller "cookie-cutter" collapses which have coalesced to form the main caldera. Notice also that many of the lava flows dark and light are 'a'a and pahoehoe, respectively have been truncated by the caldera margin. This is an indication that they erupted from the volcano summit when the caldera was full. Collapse since then has produced the present caldera.

In this manner of collapsing and filling, calderas come and go throughout the active lifetime of a basaltic volcano.

Shield volcanoes have the following characteristics:. Ash released from shield volcanoes often builds up around the vent forming a steep, round hill known as a cinder cone. A lava tube may also form, beneath the surface of the ground, when low viscosity lava develops a hard crust through which lava flows. A caldera is a large-scale volcanic crater that could be several kilometres in diameter.

The top can literally be blown off! This satellite photo shows the summit caldera of the volcano, which is 6 km in diameter and 1. On April 10, , Tambora produced the largest eruption in recorded history, which removed its estimated m-high peak and emptied its magma chamber.

Discovering Geology introduces a range of geoscience topics to school-age students and learners of all ages. The Earth beneath our feet is constantly shifting and moving, and violently with catastrophic and immediate results.

Find out more about earth hazards. We have a team of volcanologists that works on various research projects in locations around the world to help governments and local people to understand volcano behaviour.

Volcanic eruptions can be explosive, sending ash, gas and magma high up into the atmosphere, or effusive, producing lava flows and domes. Find out about the different types of volcanic hazards that put human lives, livelihoods or infrastructure at risk of harm. It may seem unwise to choose to live with such a hazardous neighbour as a volcano.

There are a number of reasons why people live alongside volcanoes. Types of volcano Discovering Geology — Volcanoes. When magma erupts at the surface as lava, it can form different types of volcano depending on: the viscosity, or stickiness, of the magma the amount of gas in the magma the composition of the magma the way in which the magma reached the surface Strictly speaking there are two broad types of volcano, a stratovolcano and a shield volcano, although there are lots of different volcanic features that can form from erupted magma such as cinder cones or lava domes as well processes that shape volcanoes.