1. Eruptions

2. Making Magma Activity depends on ____________ of magma
Lava can be thin & __________ or ___________ & lumpy

3. Magma Temperature Most rocks melt between _______-1200 °C
In Crust & Upper _____________
Pressure
Increase with ________ because of _________ of rocks
High pressure increases ___________ temperature

4. Composition of Magma Amount of Gas & Silica
Increase gas dissolved = ______________ explosiveness
_____________+ gases = carbon dioxide, water vapor, sulfur oxide, sulfuric acid
Water vapor determines _________ magma forms
Water vapor ______________ melting temperature

5. Composition ________________ = Resistance to flow
Temperature & silica content affect ____________
High viscosity = __________ magma
High silica = _____________ & sticky
Traps gases, produces explosive eruptions
Low silica = __________ & runny
Flow easily, produce quiet, non-explosive eruptions

6. Types of Magma - Basaltic
Less then __________ silica content
__________-viscosity magma
Gas ____________ escapes
______________ eruptions
Ex: Kilauea & Mauna Loa

7. Types of Magma - Andesitic
50-_________ silica content
Oceanic-continental ___________ zones
_______________ viscosity
_______________ explosiveness
Send __________ volumes of ash & debris
Ex: Colima Volcano in Mexico

8. Types of Magma - Rhyolitic
More than _________ silica content
Magma ___________ with water and silica
_____________ viscosity
____________ volumes of gas trapped
___________ explosive

9. Explosive Eruptions
If lava is too ____________ to flow, pressure builds up until an __________________
_____________ = ash and pieces of solidified lava or pieces of crust
Classified by _________
________ = smallest tephra, diameter is less then 2 mm
Blocks = largest tephra

10. Ash Can ________ into atmosphere
_________ sulfuric acid droplets remain in stratosphere and ____________ sun’s rays and ______________ global temperature

11. Pyroclastic Flows Tephra + gases VERY ___________

12. In-Class Assignment
18.2 Study Guide WKT