What is a volcano What is a nonexplosive

What is a volcano?

What is a non-explosive eruption? • The most common type of eruption • Releases a lot of lava that flows calmly • Created most of the sea floor and also the Northwest USA • This is how Hawaii was formed

What kind of volcano is this? • A shield volcano – cause its Hawaii • But it could also be a composite – cause they sometimes ooze

What is a hot spot? A very hot place in the mantle of the earth – it burns a hole through the tectonic plates and volcanoes form – this is how Hawaii formed.

What kind of volcano is this? Composite Volcanoes Describe it • Has both explosive and non explosive eruptions • Sometimes they ooze and leave layers of rock • Sometimes they explode and leave gravel • The most common type of volcano • Sides get steeper towards the top

What kind of volcano is this? Shield Volcano Describe it • • Formed from non explosive eruptions Gently sloping sides Large base Hawaiian islands are shield volcanoes

What is lapilli? • A pyroclastic material • Pebble like bits of magma • Like the ones that made the volcano at Paricutin, Mexico

What kind of volcanic eruption is this?

What is a volcanic bomb? • A pyroclastic material that is formed when large blobs of magma harden in the air • It basically rains boulders!

Most earthquakes and volcanoes occur near subduction zones. Denser oceanic plates move under continental plates. What kind of boundary is this?

How does pyroclastic material form? • When magma is ejected from a volcano and hardens during an explosive eruption

What is a crater? A funnel shaped pit around the central vent at the top of many volcanos

What is a caldera? A large semicircular depression that forms when the magma chamber begins to empty and the magma chambers roof collapses

What is viscosity? A measure of how fluid something is high viscosity means slow flow (like pancake syrup) Low viscosity means fast flow (like water)

What is this? Why is it dangerous? pyroclastic flow up to 1000 degrees! Very fast! Breathing ash will kill you

What are volcanic blocks? • A pyroclastic material • Large pieces of solid rock that have erupted from a volcano

What is volcanic ash? • A pyroclastic material • Tiny, dust-like particles of hardened magma

What is this a picture of? The Ring of Fire

What is an explosive eruption? • Incredibly destructive • They create clouds of ash, gas & hot debris. • Magma is thrown in the air and hardens before it drops. • The ash can cause climate change!

Which plate is the ring of fire around? The Pacific Plate

Which type of lava is this? Aa – pours quickly, forms a brittle crust, less silica so it has a low viscosity

Which type of lava is this? Pahoehoe – it flows slowly, has a glassy surface, high viscosity (more silica)

Which type of lava is this? Blocky – oozes from volcanoes and does not travel far – more silica so high viscosity

Which type of lava is this? Pillow – forms underwater less silica so it flows quickly low viscosity

Ash (pyroclastic material) Crater Main Vent Lava Side Vent (pyroclastic material) Label this mountain with: Main Vent, Side Vent, Crater, Ash, and Lava

What are the 3 categories of volcanoes? • Extinct – has not exploded in recorded history – probably won’t ever again • Dormant – quiet for 200 years – may erupt again • Active – currently erupting or showing signs that it will soon

What do you need to get an explosive eruption? • High silica content – the silica blocks the vents so pressure build up • More water – because water expands rapidly and turns to steam – causes more pressure • More volcanic gases because the gases expand rapidly – like water

The pacific plate is shrinking! Subduction is occurring at almost every edge of the plate. That’s why the ring of fire is there!

What kind of volcano is this? Cinder Cone Describe it • Cinder cones are the smallest volcanoes. • Made of small bits of lava that harden before they hit the ground. • The whole volcano is like a large gravel pile. • Small base with steep sides • Built from pyroclastic material (Paricutin, Mexico)

And even if you are not anywhere near the explosion – the ash can be deadly

Name 4 signs that a volcano might erupt 1. Change in magnitude of earthquakes 2. Change in volume and composition of volcanic gases 3. Change in the slope of the volcano 4. Change in the temperature of the volcano’s surface