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

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