Magma Composition
Felsic/Intermediate Volcanoes
Mafic Volcanoes
Miscellaneous
100
What is the primary element that determines magma viscosity?
What is silica?
Silica (SiO₂) — more silica = higher viscosity.
100
What are the two types of gasses that can come from a volcano?
CO2 - Carbon Dioxide, heats up the earth
SO2 - Sulfur Dioxide, mixes with moisture to create sulfuric acid (acid rain)
100
Is mafic magma viscous or non-viscous?
What is non-viscous? Moves fast and far!
100
What is the VEI of Hawaii?
What is VEI≤2?
200
Mafic magma encounters with felsic magma- what is the composition?
What is intermediate magma?
200
Which eruption was VEI-8 and may have caused a human population bottleneck?
What is Toba? (Indonesia, ~74,000 years ago).
200
Which type of basaltic eruption, a traps, is close to the stratovolcano in Yellowstone?
What is the Columbia River Basalts
200
What happens to a rock's composition when it fully melts instead of partially melts?
What is stays the same?
300
If mafic magma underwent fractionation, which composition crystallizes last?
What is felsic magma?
300
Which eruption destroyed Pompeii and introduced the term Plinian eruption?
What is Mount Vesuvius (79 AD, VEI-5) ?
300
What is the difference between these two mafic formations- flows and traps?
Basalt flows - small, localized lava events (ex. in Hawaii or Pisgah Crater)
Traps - enormous flood basalts that cover vast regions (ex. Deccan or Siberian Traps) and can cause mass extinctions
300
What natural event influenced Turner’s (the painter) vivid red sunsets?
What is the Krakatoa eruption? (VEI-6, 1883)
400
A mafic rock partial melts and cools deep under the ground. Which rock is it?
What is diorite?
400
Which two VEI-7 eruptions drastically altered global climate and human history?
Tambora (1815) - "year without a summer", caused food shortages in Europe that may have influenced the French Revolution
Santorini (VEI-6-7, 3,600 years ago) - caused a volcanic winter with historic records in China
Mt. Mazama (Crater Lake, ~7,600 years ago) - describe by legends of warring gods
400
Daily Double!
The islands further away from the hotspot have eroded down to the water.
400
What is the largest eruption in your lifetime?
What is Pinatubo? VEI-6.
500
Name all four processes that change magma composition and their process'.
Partial melting - Temperature hot enough to melt more silica-rich minerals off a rock, which cools and creates a rock one-step in the left-direction (more felsic!) on the table
Fractionation - Magma cools in a magma chamber, more mafic-rich minerals crystallize first, leaving magma that is more felsic
Assimilation - Magma below melts more silica-rich country rock above, mixes to make magma more felsic
Magma mixing - When two different magma's meet and mix together
500
List the effects and how often a VEI-6, VEI-7, and VEI-8 occur.
VEI-6: Can affect on the opposite side of the world - Once in a lifetime (50-100 years)
VEI-7: Global climate change and widespread fatalities - Occurs once every 1,00 years
VEI-8: Global effects that can last around 200-1000 years - Occurs once every 10,000 to 100,000 years
500
What is the second-largest lava lake in the world? Which volcano is it located in?
What is Halemaʻumaʻu and where is Kīlauea?
500
What does the Ashfall Fossil Bed reveal about eruption timing and species death?
Birds died first (ashfall began), while large mammals lingered and suffocated weeks later (called Marie’s Disease)
Article Reading: Ashfall Fossil Beds