Question

Describe how each of the following volcanic features are formed:

Caldera.

Answer 1

• lava pours out of a central vent to form volcanic cone
• Vent is sealed when lava solidifies
• Solidifies lava blocks gases and steam beneath, preventing them from escaping
• Pressure piles up below, leading to a violent eruption which blows off the top of the cone forming depression.
• The depression is large and circular and it is known as caldera
  
  OR 
• Lava pours out of central vent to form volcanic cone
• Magma chambers are left empty/void
• Due to overlying weight at top of cone, pressure is exerted
• Top of the cone subsides forming a depression
• This depression is large and circular and is called a caldera
  
  OR 
  (outward collapsing theory)
• A volcano is build of ash and pyroclasts to form a dome
• Weak materials at the base are unable to support the overlying materials / weight
• Materials at thee base spread outward as top part subsides, leading to large depression known as caldera.