melty melty
What is the difference between magma and lava?
Magma is found below the Earth's surface, lava is found on the Earth's surface.
What is the longest recorded flight of a chicken?
13 seconds
Why are so many volcanoes found on the Ring of Fire around the margin of the Pacific Ocean?
Many subduction zones occur there
What is a caldera?
A crater that results when a volcanic eruption causes the collapse of the surface into an emptying magma chamber
What is the difference between an effusive and an explosive eruption?
Effusive: magma flows to the surface through a vent or crack without a lot of pressure, resulting in an effusive lava flow
Explosive: if rising magna gets trapped and pressure builds, then it will explode
What is decompression melting?
When rock melts because its melting temperature decreases when the pressure decreases
What is viscosity?
The resistance to flow in fluids
Which type of volcano is made from alternating layers of pyroclastic debris and effusive lava flows?
Stratovolcanoes
What are the three settings where volcanism can occur?
1. Mid-ocean ridges
2. Subduction zones
3. Hot spots (far from plate boundaries)
What is volcanic ash?
shards of glass from magma gas bubbles
What is a magma chamber?
A large pool of magma near the Earth’s surface
T or F: Lava becomes more viscosic as it cools?
TRUE
Which type of volcano is made from low viscosity lavas that can flow long distances?
Shield volcanoes
Which set of islands is a hotspot track where the islands get older northwest as the plate moves?
Hawaiian Islands
What are the three main factors that control whether a volcano will erupt explosively or effusively?
What are three ways to get hot mantle rocks to melt?
1. Increase temp
2. Decrease pressure
3. Add water to the mineralogy (hydrogen-induced melting)
What is low viscosity called?
Pahoehoe
Which is the most explosive type of volcanic eruption?
Plinian
What is the most dangerous thing about volcanos? Close and Far away
Far: ash fall
What is pumice?
volcanic rock with so many trapped gas bubbles that it floats
T or F: An eruption can be explosive AND have lava flow
True but it is rare
(2015 Villarrica Vulcanian eruption in Chile)
Which factor is the Volcanic Explosivity Index (VEI) NOT based on?
Extend of the lava flows
Anything moving underground can cause a _______
Harmonic tremor
by the amount of ash and rock ejected
What is a lahar and how many people have they killed?
mudflows containing ash, soil, rock, and water (occur days or months after eruption)
10s of thousands