Volcanoes
What are Volcanoes?
Volcanic mountains are formed when molten
rock from deep inside the Earth erupts through the crust and piles up on itself.
A volcano opens downwards where there is a pool of lava (which is hot liquid
rocks) below the surface of the earth. When pressure builds up, from a volcano an
eruption takes place. When it erupts, gases and rock shoot up through the
opening of a volcano and spills or fills the air with lava fragments.
When a volcano erupts it has been known to knock down entire forests, small villages and sometimes even towns and cities.
Eruptions cause
and triggers
· Lava flows
· Lateral blasts
· Hot ash flows
· Mudslides
· Mud-flows
· Avalanches
· Falling ash
· Tsunamis
· Flash floods
· Earthquakes
· Rock fal
Where does volcanism plate occur?
Plate boundaries are when two plates are either moving away from one another, moving toward one another, or sliding past one another. Adjacent plates are outlined by three types of boundaries defined by relative motion:
Divergent plate boundaries -- Plates separate from one another.
Convergent plate boundaries -- Plates tend to move toward on one another.
Transform plate boundaries -- Plates slide past one another.
Volcanism exist at divergent and convergent plate boundaries, there is no lack of significant volcanism connected with transform plate boundaries.
Spreading centre volcanism occurs at divergent plate margins, and seduction zone volcanism occurs at convergent plate margins. Intraplate volcanism describes volcanic eruptions within tectonic plates.
Predicting & preparing for a volcano Eruption
It's impossible to prevent volcanoes erupting, but prediction is the most important aspect. Prediction gives people time to evacuate the area there in and make preparations for an eruption.
Volcanologists (experts who study volcanoes), predict eruptions by a volcano becoming active. By a volcano becoming active it gives off a number of warning signs.
Here are warning signs and monitoring techniques volcanologists find and use
Warning signs
· There Hundreds of small earthquakes that are caused as magma rises up through cracks in the Earth's crust.
· The temperatures around volcanoes rise as activity increases.
·When a volcano is about to erupt it starts to release gases. The higher the sulfur content of these gases, the closer the volcano is to erupting.
Monitoring techniques
·Seismometers are used to detect earthquakes.
·Thermal imaging techniques and satellite cameras can be used to detect heat around a volcano.
·Gas samples may be taken and chemical sensors used to measure sulfur levels.
As time goes on techniques for predicting and monitoring volcanic activity are becoming progressively accurate. Volcanoes that have been active in recent years such as Mount St Helens in the USA and Mount Etna in Italy are monitored closely at all times. This is because people that live nearby would benefit from early-warning signs of an eruption. However, as well as prediction of if an volcano is going to erupt, people should also be prepared.
Preparing for an eruption
A plan is always needed for dealing with possible eruptions.
Planning for a volcanic eruption includes:
·creating an exclusion zone around the volcano
·being ready and able to evacuate residents
·having an emergency supply of basic provisions, such as food
·funds need to be available to deal with the emergency and a good communication system needs to be in place