Volcanoes Flashcards
How are volcanoes formed?
Volcanoes are formed when molten rock (magma) from the mantle bursts through a weakness in the Earths crust.
What is the red hot molten rock that is released from a volcano called?
Lava
A scientist who studies volcanoes is called a?
volcanologist
What comes out of a volcano?
When the volcano erupts, lava flows from the vents and red-hot fragments of rock, dust and ash, steam and other gases shoot out of the crater.
what are the four main types of volcanoes?
Geologists generally group volcanoes into four main kinds–cinder cones, composite volcanoes, shield volcanoes, and lava domes.
What is a pyroclastic flow?
Is a fast moving current of hot gas, ash and rock/lava bombs.
How fast does pyroclastic flow and what is its temperature?
It can reach speeds of up to 720 km/hour can reach temperatures of about 700 C.
What does pyroclastic flows generate?
It generates lahar when water and ash mix
What is Lahar?
A lahar is a hot or cold mixture of water and rock fragments that flow quickly down the slopes of a volcano.
How fast does lahar travel and how far can it travel?
They can travel up to 200 km/hour as they are as hard as concrete and they can travel 300 km!
When a volcano is ‘active’ what does this mean?
Has had at least one eruption during the past 10,000 years
When does it mean a volcano is ‘erupting’ what does that mean?
An active volcano that is having a eruption.
What does it mean when a volcano is ‘dormant’?
An active volcano that is not erupting (or has not erupted for about 20 years) but is supposed to erupt again.
What does it mean when a volcano is ‘extinct’?
It has not had a eruption for at least ‘10,000’ years and is not expected to erupt again in a comparable time scale of the future.
Where are volcanoes found?
Most volcanoes lie close to the edges of the tectonic plates, but some lie over hot spots.
What is a volcano’s ‘hot spot’?
A volcanic ‘hot spot’ is an area in the mantle from which heat rises as a thermal plume from deep in the Earth.
What are hot spots?
A hot spot is a region deep within the Earth’s mantle from which heat rises through the process of convection. This heat facilitates the melting of rock. The melted rock, known as magma, often pushes through cracks in the crust to form volcanoes.
What is the crater on the top of a volcano?
The circular depression at the top of the volcano
What is the magma chamber?
Store of underground magma
What are the 6 steps when a volcano is formed?
- Low-density magma rises under pressure into the magma chamber.
- Magma rises towards the surface.
- Dissolved gases expand as the magma rises.
- The expanding gases cause an explosion that rips open the vent.
- Ash, cinders and dust rain down onto the ground.
- Lava blasts into the air.
Some volcanoes will form in the middle of a tectonic plate. This phenomenon is called?
Hot spots
b. Briefly describe how a volcano would form at in the middle of a tectonic plate.
A hot spot is a region deep within the Earth’s mantle from which heat rises through the process of convection.
This heat the melting of rock returning it to magma, which often pushes through cracks in the crust to form volcanoes.
