Week 05 Volcanism and its Landforms PDF

Physical Geography: Volcanism and Its Landforms 10/1/2024 – 10/2/2024 PROFESSOR PETE PULEO 1 Volcanism 2 Learning Objectives Describe the global distribution of volcanic activity and explain its relationship with plate boundaries Explain how the compositio...

Physical Geography: Volcanism and Its Landforms 10/1/2024 – 10/2/2024 PROFESSOR PETE PULEO 1 Volcanism 2 Learning Objectives Describe the global distribution of volcanic activity and explain its relationship with plate boundaries Explain how the composition of magma influences volcanic eruptions Provide examples of solid, liquid, and gaseous ejecta from volcanic eruptions Cite some dramatic historical examples of human interaction with volcanic environments 3 Volcanoes Eruption of molten rock at Earth's surface often accompanied by rock fragments and gases Mt. Shasta (Pacific Northwest, 10,000 ft, last erupted in 1786) 4 Volcanology The study of volcanoes 5 Sampling Lava 6 Where do Volcanoes Occur? 7  Where do Volcanoes Occur? Pacific Ring of Fire https://www.researchgate.net/figure/Global-map-of-the-distribution-and- status-of-Holocene-volcanoes-as-listed-in-VOTW422_fig4_280714920 8 What are the Impacts of Volcanic Eruptions? 1973 eruption at Heimaey (island near Iceland) Lava and ashfalls that forced evacuation and partially destroyed the town Local citizens used seawater to cool lava and protect parts of the town 9  What Creates Volcanoes? Plate Boundaries! https://www.britannica.com/science/volcano/Volcanoes-related-to-plate- boundaries 10  Volcano Status Active – A volcano that has erupted in the last 10,000 years Mt. Hood (Oregon, 11,250 ft, Major eruption in 1781) https://www.usgs.gov/observatories/yvo/news/active-dormant-and-extinct- clarifying-confusing- classifications#:~:text=Mount%20Thielsen%20(2%2C799%20m%20or,erupted% 20about%20300%2C000%20years%20ago. 11  Volcano Status Dormant – A volcano that hasn’t erupted recently, but could in the future because magma lies below the surface Yellowstone National Park (Hot springs and geysers indicate magma in subsurface) https://www.usgs.gov/observatories/yvo/news/active-dormant-and-extinct- clarifying-confusing- classifications#:~:text=Mount%20Thielsen%20(2%2C799%20m%20or,erupted% 20about%20300%2C000%20years%20ago. 12  Volcano Status Extinct – A volcano that hasn’t erupted recently, has no sign of magma below the surface, and has been heavily eroded Mt. Thielsen (Oregon, ~9,200 ft, last erupted 300,000 years ago) https://www.usgs.gov/observatories/yvo/news/active-dormant-and-extinct- clarifying-confusing- classifications#:~:text=Mount%20Thielsen%20(2%2C799%20m%20or,erupted% 20about%20300%2C000%20years%20ago. 13  Properties of Magma https://open.maricopa.edu/geologylab/chapter/volcanic-hazards/ 14  Properties of Magma More SiO2 -> More viscosity https://sites.northwestern.edu/sethstein/other-courses-taught/earth-202- earths-interior-in-person/magma-viscosity/ 15  Properties of Magma https://opentextbc.ca/geology/chapter/4-2-magma-composition-and-eruption- style/ 16  Properties of Mafic Magma https://open.maricopa.edu/geologylab/chapter/volcanic-hazards/ 17  Properties of Felsic Magma https://open.maricopa.edu/geologylab/chapter/volcanic-hazards/ 18  Summary of Magma Properties https://geo.libretexts.org/Bookshelves/Geology/GEOS%3A_A_Physical_Geology_ Lab_Manual_for_California_Community_Colleges_%28Branciforte_and_Haddad %29/08%3A_Volcanoes_and_Volcanic_Activity/8.01%3A_Front_Matter 19 Erupted Materials – Liquids Lava – Molten rock on the surface Flows through tube like openings in the crust called vents or longer cracks called fissures 20  Lava Classification Pahoehoe – Wrinkled and ropy pattern from low viscosity lava cooling on surface https://en.wikipedia.org/wiki/Lava 21  Lava Classification Aa – Stony, rough pattern from high viscosity lava cooling on surface https://en.wikipedia.org/wiki/Lava 22  Lava Classification Pillow – Smooth, round features from lava cooling underwater https://en.wikipedia.org/wiki/Lava 23  Erupted Materials - Solids Pyroclastics – Solidified fragments from a volcanic eruption https://commons.wikimedia.org/wiki/File:Structure_volcano_unlabeled.svg 24  Erupted Materials - Solids Differ by size https://slideplayer.com/slide/5811540/ 25  Pumice Pyroclastic rock type Very low density (it floats!) https://en.wikipedia.org/wiki/Pumice https://volcano.oregonstate.edu/news/floating-pumice-oceanic-hazard 26  Erupted Materials - Gases SO2 leads to sulfuric acid and acid rain CO2 leads to climate change Other aerosols reflect sunlight 27  Debris Flows Lahars –A flood of ash, mud, and water rushing down slope after an eruption melts snow/ice or heavy rainfall https://en.wikipedia.org/wiki/Lahar 28  Debris Flows Pyroclastic Flows – A rapid flow of hot gas and volcanic ash https://education.nationalgeographic.org/resource/pyroclastic-flow/ 29 https://www.nps.gov/subjects/volcanoes/anatomy-of-a-volcano.htm 30 Eruption Types 31 Forecasting Volcanic Eruptions https://www.youtube.com/watch?v=IJl4PnR4mf0 32 Activity 1 Description Do some independent research on a volcanic eruption that has happened in the last 200 years and to answer the following questions. Be ready to share with a partner/the class. 1) When did the eruption occur? 2) Where did the eruption occur? 3) What was the kind of volcano? 4) What were the impacts on society? 5) What is the status of the volcano today (active, dormant, extinct)? 33 Volcanic Landforms 34 Learning Objectives Draw and describe the major types of volcanoes Understand how tectonic environments influence magma composition and volcanic landforms 35 What are the Main Types of Volcanic Landforms? Calderas Composite Volcanoes Cinder Cones Shield Volcanoes Plateaus or Plains 36 Calderas A collapse of the ground surface associated with a volcano that leaves behind a large basin Crater Lake (Oregon, 2,000 ft deep, formed 7,700 years ago) 37 Caldera Formation Felsic lava 1 3 High viscosity Explosive 2 4 Crater Lake (Oregon, 2,000 ft deep, formed 7,700 years ago) 38  Composite Volcanoes (Stratovolcano) High, steep sided volcanoes composed of layered lavas and compacted pyroclastics Mt. Fuji (Japan, 12,400 ft, last erupted 1708) https://en.wikipedia.org/wiki/Mount_Fuji 39 Composite Volcano Formation Formed from intermediate magmas (between mafic and felsic) 40  Cinder Cones Small volcanoes that emit largely pyroclastics Cinder Cone (California, 750 ft, erupted in 1650) https://www.nps.gov/articles/000/cinder-cones.htm 41  Cinder Cone Formation Composed of layers of poorly consolidated, pyroclastic material https://www.nps.gov/articles/000/cinder-cones.htm 42 Shield Volcanoes Volcanoes with low relief but a very large area Example: Eruption at Kilauea ongoing for 30 years 43 Shield Volcano Formation Layers of mafic magma that can flow far due to its low viscosity 44  Plateaus or Plains Large areas of rock from the accumulation of many lava flows that spread across large areas from numerous vents Columbia Plateau (Washington, Oregon, Idaho) https://www.britannica.com/place/Columbia-Plateau 45  Plateau or Plain Formation Mafic lava flows through many vents and fissures https://www.geo.mtu.edu/KeweenawGeoheritage/BlackLavas/Flood_Basalts.ht ml 46  Tectonics and Volcanism Divergent Boundaries -> Spreading Ridge Volcanism https://opentextbc.ca/physicalgeology2ed/chapter/4-1-plate-tectonics-and- volcanism/ 47  Tectonics and Volcanism Convergent Boundaries -> Composite Volcanism https://opentextbc.ca/physicalgeology2ed/chapter/4-1-plate-tectonics-and- volcanism/ 48  Tectonics and Volcanism Mantle Hot Spots -> Shield Volcanism https://opentextbc.ca/physicalgeology2ed/chapter/4-1-plate-tectonics-and- volcanism/ 49 Tectonics and Volcanism Mantle Hot Spots are stationary, meaning they can be used to track plate movement over time Example: Hawaiian Island hot spot volcanism 50  Volcanic Landform Summary https://geo.libretexts.org/Bookshelves/Geology/GEOS%3A_A_Physical_Geology_ Lab_Manual_for_California_Community_Colleges_%28Branciforte_and_Haddad %29/08%3A_Volcanoes_and_Volcanic_Activity/8.01%3A_Front_Matter 51 Activity 2 Description Work with the partner to answer the following questions. 1) Draw and describe shield volcanoes, composite volcanoes, and calderas. 2) Distinguish the lava characteristics (silica content, viscosity, flow speed, gas content, and explosivity) of each volcano type in question 1. 52  Activity 2 Solution 1) Draw and describe shield volcanoes, composite volcanoes, and calderas. https://ngsmagnified.com/textbooks/forces-that-shape-the-earth/section-3- volcanoes-2/ 53  Activity 2 Solution 1) Draw and describe shield volcanoes, composite volcanoes, and calderas. https://ngsmagnified.com/textbooks/forces-that-shape-the-earth/section-3- volcanoes-2/ 54  Activity 2 Solution 1) Draw and describe shield volcanoes, composite volcanoes, and calderas. https://ngsmagnified.com/textbooks/forces-that-shape-the-earth/section-3- volcanoes-2/ 55 Activity 2 Solution 2) Distinguish the lava characteristics (silica content, viscosity, flow speed, gas content, and explosivity) of each volcano type in question 1. Shield – Mafic (low silica), low viscosity, fast flow speed, low gas content, slightly explosive Composite – Intermediate (moderate silica), medium viscosity, medium flow speed, moderate gas content, somewhat explosive Caldera – Felsic (high silica), high viscosity, slow flow speed, high gas content, explosive 56  Multiple Choice Practice Qs Take ~ 1 minute to independently think about and write down an answer to the question on the board. Then, turn to a partner and discuss your reasoning for choosing that answer. Write a second answer after you have discussed your thoughts with a partner (its okay to write the same answer twice or change your answer, just be sure to have two answers per question). Finally, we will discuss the correct answer as a class. Be sure to have your name and date on top and hand in before you leave. 57 Question 1 A volcano that has erupted in recorded history is said to be: A) Dormant B) Active C) Extinct D) Ongoing 58 Solution 1 A volcano that has erupted in recorded history is said to be: A) Dormant B) Active C) Extinct D) Ongoing 59 Question 2 Which statement is NOT true regarding lavas that are high in silica? A) may produce explosive eruptions B) flow relatively quickly C) are quite viscous D) are low in magnesium and iron 60 Solution 2 Which statement is NOT true regarding lavas that are high in silica? A) may produce explosive eruptions B) flow relatively quickly C) are quite viscous D) are low in magnesium and iron 61 Question 3 Crater Lake formed after the eruption of which kind of volcano? A) stratovolcano B) cinder cone C) shield volcano D) caldera 62 Solution 3 Crater Lake formed after the eruption of which kind of volcano? A) stratovolcano B) cinder cone C) shield volcano D) caldera 63 Question 4 Solid fragments ejected from a volcano are called: A) pahoehoe B) lahars C) pyroclastics D) lava 64 Solution 4 Solid fragments ejected from a volcano are called: A) pahoehoe B) lahars C) pyroclastics D) lava 65 Question 5 A type of volcano that's mostly associated with subduction zones along convergent plate boundaries are: A) stratovolcano B) cinder cones C) lava domes D) shield volcanoes 66 Solution 5 A type of volcano that's mostly associated with subduction zones along convergent plate boundaries are: A) stratovolcano B) cinder cones C) lava domes D) shield volcanoes 67 Question 6 Hot, fast, down-slope, turbulent flow of solid volcanic material mixed with gas is called: A) lahar B) pyroclastic flow C) eruption column D) ash fall 68 Solution 6 Hot, fast, down-slope, turbulent flow of solid volcanic material mixed with gas is called: A) lahar B) pyroclastic flow C) eruption column D) ash fall 69