Volcano
Volcano is a mountain that forms when magma reaches the surface.
Formation of a Volcano
Under certain conditions, small amounts of mantle rock can melt, forming liquid magma. The magma rises upward through the crust, erupting at the surface as a volcano. The Magma rises upwards since it is less dense than the other solid rock around and above it
How Volcano Erupts
Magma is under pressure and contains dissolved gases which are carbon dioxide and water vapor.
When magma approaches to the surface, lower pressures allows the magma to expand rapidly.
Structure of a Volcano
Before erupting magma often collects in a pocket called the magma chamber. It starts to accumulate until it is ready to erupt.Then magma rises to the surface in a narrow vertical channel called the pipe. An opening in the ground which are magma escapes to surface is called the vent.At the top of the central vent there is a bowl shaped pit called the crater. If the shell of the volcano collapse inward it creates a huge depression,this is called the caldera.
Quiet and Explosive Eruptions
Volcanoes can erupt either quietly or explosively. Magma can vary in viscosity which is the resistance for the magma to flow. Magma with high viscosity is thick and resists flowing, in the other hand magma with low viscosity has thin and flows easily. The 3 main factors of viscosity are temperature, water content, silica content.
Quiet Eruptions
Volcanoes with very hot temperature and low - silica magma erupts quietly. In a quiet eruption, lava erupts in a stream of low - viscosity lava called the lava flow. Produce 2 kinds of lava, one is hot fast lava called pahoehoe and the cool slow one called aa
Explosive Eruptions
High silica magma produce Explosive eruptions. Since thick magma can clog volcano pipe and the steam can create greater pressure. When the volcano explodes, lava and hot gases are hurled outward. Lava then cools and solidifies very quickly and shatters into pieces. These particle range in size such as dust, ash, pebble sized cinders, to bombs, small car size.
Location and Types of Volcanoes
Most volcanoes occur along plate boundaries or at hot spots in the crust.
Volcanoes form along converging plate boundary where oceanic plates subducted into the mantle. As it sinks through the mantle it causes the plates to melt and the Magma forms and rises onto the surface. Ring of Fire is a region were many volcanoes have forms along the trenches that rim the Pacific Ocean. Some volcanoes occur at hot spots. Hot spot is a region where hot rock extends from within the mantle to surface
Different types of volcanic eruption is caused by different kinds of volcanoes. 3 major types of volcanoes - shield volcano, cinder cones, composite volcanoes.
Quiet eruption of low-viscosity lava produces wide flat volcano called the shield volcano .
An eruption is entirely ash and cinders creates a small step sided volcano is called the cinder cone.
Volcano that forms from explosive eruptions that produce a combination of lava and ash is called the composite volcano.
Other Igneous Features
Sometimes magma doesn't reach the surface and cools in the crust, this igneous rock can be pushed out and and get exposed on the surface. Igneous Features formed by magma include batholiths, sills, dikes, and volcanic necks
Batholiths is the largest type of intrusive igneous rock mass and it is often form the core of mountain.
l If the crack is parallel to existing rock layers and magma gardened in between it it becomes sill
If the crack cuts across the rock layers, the hardest magma it is called a dike
When magma hardens in a volcano’s pipe i becomes a volcanic neck
Formation of a Volcano
Under certain conditions, small amounts of mantle rock can melt, forming liquid magma. The magma rises upward through the crust, erupting at the surface as a volcano. The Magma rises upwards since it is less dense than the other solid rock around and above it
How Volcano Erupts
Magma is under pressure and contains dissolved gases which are carbon dioxide and water vapor.
When magma approaches to the surface, lower pressures allows the magma to expand rapidly.
Structure of a Volcano
Before erupting magma often collects in a pocket called the magma chamber. It starts to accumulate until it is ready to erupt.Then magma rises to the surface in a narrow vertical channel called the pipe. An opening in the ground which are magma escapes to surface is called the vent.At the top of the central vent there is a bowl shaped pit called the crater. If the shell of the volcano collapse inward it creates a huge depression,this is called the caldera.
Quiet and Explosive Eruptions
Volcanoes can erupt either quietly or explosively. Magma can vary in viscosity which is the resistance for the magma to flow. Magma with high viscosity is thick and resists flowing, in the other hand magma with low viscosity has thin and flows easily. The 3 main factors of viscosity are temperature, water content, silica content.
Quiet Eruptions
Volcanoes with very hot temperature and low - silica magma erupts quietly. In a quiet eruption, lava erupts in a stream of low - viscosity lava called the lava flow. Produce 2 kinds of lava, one is hot fast lava called pahoehoe and the cool slow one called aa
Explosive Eruptions
High silica magma produce Explosive eruptions. Since thick magma can clog volcano pipe and the steam can create greater pressure. When the volcano explodes, lava and hot gases are hurled outward. Lava then cools and solidifies very quickly and shatters into pieces. These particle range in size such as dust, ash, pebble sized cinders, to bombs, small car size.
Location and Types of Volcanoes
Most volcanoes occur along plate boundaries or at hot spots in the crust.
Volcanoes form along converging plate boundary where oceanic plates subducted into the mantle. As it sinks through the mantle it causes the plates to melt and the Magma forms and rises onto the surface. Ring of Fire is a region were many volcanoes have forms along the trenches that rim the Pacific Ocean. Some volcanoes occur at hot spots. Hot spot is a region where hot rock extends from within the mantle to surface
Different types of volcanic eruption is caused by different kinds of volcanoes. 3 major types of volcanoes - shield volcano, cinder cones, composite volcanoes.
Quiet eruption of low-viscosity lava produces wide flat volcano called the shield volcano .
An eruption is entirely ash and cinders creates a small step sided volcano is called the cinder cone.
Volcano that forms from explosive eruptions that produce a combination of lava and ash is called the composite volcano.
Other Igneous Features
Sometimes magma doesn't reach the surface and cools in the crust, this igneous rock can be pushed out and and get exposed on the surface. Igneous Features formed by magma include batholiths, sills, dikes, and volcanic necks
Batholiths is the largest type of intrusive igneous rock mass and it is often form the core of mountain.
l If the crack is parallel to existing rock layers and magma gardened in between it it becomes sill
If the crack cuts across the rock layers, the hardest magma it is called a dike
When magma hardens in a volcano’s pipe i becomes a volcanic neck