Post on 24-Dec-2015
18.2 - Eruptions
Making Magma
Activity depends on ____________ of magma Lava can be thin & __________ or ___________
& lumpy
Magma
Temperature Most rocks melt between _______-1200 °C In Crust & Upper _____________
Pressure Increase with ________ because of _________ of
rocks High pressure increases ___________ temperature
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
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
Types of Magma - Basaltic
Less then __________ silica content __________-viscosity magma Gas ____________ escapes ______________ eruptions Ex: Kilauea & Mauna Loa
http://media-2.web.britannica.com/eb-media/31/20231-004-008EFA7E.jpg
Types of Magma - Andesitic
50-_________ silica content Oceanic-continental ___________ zones _______________ viscosity _______________ explosiveness Send __________ volumes of ash & debris Ex: Colima Volcano in Mexico
http://images.livescience.com/images/050531_colima_volcano_04.jpg
Types of Magma - Rhyolitic
More than _________ silica content Magma ___________ with water and silica _____________ viscosity ____________ volumes of gas trapped ___________ explosive
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 mmBlocks = largest tephra
Ash
Can ________ into atmosphere _________ sulfuric acid
droplets remain in stratosphere and ____________ sun’s rays and ______________ global temperature
http://geology.com/articles/volcanic-ash/volcanic-ash-column.jpg
Pyroclastic Flows
Tephra + gases VERY ___________
http://vulcan.wr.usgs.gov/Imgs/Jpg/MSH/Images/MSH80_pyroclastic_flow_from_st_helens_crater_08-07-80.jpg
In-Class Assignment
18.2 Study Guide WKT