The different types of lava results in the different types of volcanoes.
(ie:Acidic lava produces acidic lava volcanoes.) Let us discover the 2 types of lava...
=> produced at the constructive plate boundary by the upward movement of magma from the mantle
=> it is hot
=> it is fluid, less viscous, flows more rapidly than acidic lava (imagine it as water)
=> flows for quite some distance before solidfying
=> forms gentle-sloping shield/basic lava volcnoes which erupt quietly
=> produced when there is subduction at the destructive plate boundary
=> the subducting oceanic crust melts and the magma produced rises to the surface
=> it is not as hot as basic lava
=> it is viscous (sticky), moves slowly (imagine it as glue)
=> cools and solidifies quickly, does not flow far
=> produces steep-sided volcanoes ie: Mt Fuji in Japan
=> causes powerful and loud explosions
Example of an acidic lava volcano.
Shield/Basic Lava Volcano
The basic lava volcano is formed from basic lava which is fluid and flows rapidly.
It spreads over a huge area before solidifying.
This results in a gentle-sided volcano which erupts gently.
Muana Loa in Hawaii, USA is one such shield volcano.
A shield volcano
Acidic Lava Volcano
Acidic lava forms this type of volcanoes. As the lava is thick and viscous, it is slow-flowing and solidies quickly near the vent.
This produces a cone with steep slopes. This kind of volcanoes usually erupts violently.
Mt Stromboli in Italy in an acidic lava volcano.
Composite volcanoes consists of alternate layers of viscous lava, ash and cinder. It is generally steep towards the top and gentler at the base.
The viscous lava solidifies in the central pipe, blocking the passageway. This prevents rising magma and trapped gases from escaping, building up pressure beneath.
There will be and explosive eruption of ash and cinders at first, which will drop back around the vent. Lava then excapes and flows over the ash and cinders. Viscous lava solidies
in the pipe once again, and this process is repeated again. Violent eruptions of ash and cinders followed by lava forms a composite volcano.
Lava often escapes through the sides of the cone and builds up to form a secondary cone.
Mt Mayon in Philippines is a composite volcano.
Mount Mayon, a composite volcano.