Mt. Fujiyama, Japan

1. Volcanism & Extrusive expulsion of molten rock (LAVA), gases and water onto the surface of the Earth. • Igneous Activity - 550 active volcanoes > Active = erupted in historic times. - e.g. Mauna Loa and Kilauea (Hawaii) - Mt. St. Helens (Washington) - Mt. Pinatubo (Philippines) - Mt. Fujiyama (Japan) - Mont Serrat (Caribbean) Mt. Fujiyama, Japan

2. Dormant Extinct Volcanoes vs Dormant volcanoes Dormant volcanoes • • - have not erupted recently, but may do so again. - have not erupted recently, but may do > Mt. Vesuvius (Italy) > Mt. Vesuvius (Italy) Extinct volcanoes • • Extinct or inactive volcanoes - have not recently erupted - nor do they give indications of erupting in the future. Thousands of these > > types ofvolcanoes exist. Mt. Kilamanjaro (Tanzania,Africa)

3. Volcanoes, Craters, Domes, Calderas • Conical mountains - central vent where lava, gases, and pyroclastic materials are erupted. - Craters - circular opening at summit - generally less than 1 km in diameter - Dome - a large mound of viscous, felsic lava - commonly plugs the central vent • Calderas - a collapsed volcanic summit - greater in diameter - have steep sides.

4. Unzen Volcano, Japan shown with Lava dome and lahars (volcanic debris flows)

5. Caldera

7. Bathymetry map of Crater lake, Oregon

8. Summit of Kilauea-inner crater

9. Volcanoes types

10. Olympus Mons, a shield volcano

11. A small shield volcano in Iceland

12. a.k.a.- stratovolcanoes • - interbedded pyroclastics and lavas. - typically andesitic to rhyolitic lava > intermediate to felsic magma composition - Found on continents and island arcs > mostly associated with convergent plate boundaries (subductive) > examples of composite Mt. St. Helens, Mt. Vesuvius, Mt.Pinatubo, Mt. Fujiyama, Mt. Kilamanjaro., Mt. Rainier (photo) Composite Volcanoes

13. Stratovolcano formation

14. Composite Volcanoes Mayon volcano, Philippines, is a Mayon volcano, Philippines, is a View of Mount St. Helens, View of Mount St. Helens, nearly symmetrical composite nearly symmetrical composite Washington in 1978. Washington in 1978. volcano. volcano.

15. Cinder Cones Primarily cinder-sized (0.25-1.0 mm) material. but may have other sizes too. Cinders fall to Earth and collect around the vent. have steep slopes up to 33 degrees smaller than shield volcanoes, usually less than 400 m tall Form on the flanks of larger volcanoes.

16. Cinders and volcanic ash

17. Development of Cinder Cone Development of Cinder Cone

19. Lava Types Pahoehoe lava (smooth & ropey) in Aa lava (rough and blocky) also Pahoehoe lava (smooth & ropey) in Aa lava (rough and blocky) also Hawaii. in Hawaii. Hawaii. in Hawaii.

20. Pillow Lavas These bulbous masses of pillow These bulbous masses of pillow lava formed when lava erupted & lava formed when lava erupted & cooled under water. cooled under water. 1 meter 1 meter

21. Lava Fountain Lava Fountain

22. Pyroclastic Ash Flow ' aka Nuee Ardentes aka Nuee Ardentes Pyroclastic ash- lava blown up into the air • smaller stuff is ash, larger stuff are called "bombs" Pyroclastic Ash Flow • extremely fast (100's m/sec) • extremely hot - sometimes glowing redhot • extremely lethal - many deaths associated with volcanic eruptions are related to these events e.g., Pompeii and Herculanum >

23. Glowing Ash clouds- Nuee Ardentes

24. Ash plume from a stratovolcano eruption

25. Pyroclastic flow , Nuee Ardente

27. , Lahars & Nuee Ardentes • Lahars are mud flows that often occur after eruptions. • Nuée ardentes are mobile dense clouds of incandescent ash that can move downhill at , speeds up to 100 km/hr. Mt Pelee destroyed St. Pierre on the island of Martinique, West Indies in 1902

28. The effects of explosive volcanic activity

29. Gases and Magma • Volcanic gases - water vapor - carbon dioxide - nitrogen - sulfur oxides - hydrogen sulfide - chlorine • Felsic magmas - highly viscous : Si-rich - inhibits the expansion of gases - pressure builds up - explosive eruptions, like Mt. St. Helens. • Mafic magmas - lower viscosity - lower gas pressure - erupt rather quietly, like Hawaiian Volcanoes.

30. Lake Nyos, a volcanic lake in Cameroon, Africa CO2 emitted from the acidic lake killed 1700 villagers near the lake in 1986

31. Mt. St. Helens

32. Effects of Volcanic activity • builds up mountains and new land; also destroys land - (Lithosphere-aka. GEOSPHERE) • destroys many living things - (biosphere) • ejects ash and gases into the air blocking sunlight (exosphere) • Changes weather and climate patterns for several months to a year - (atmosphere) • Causes changes in drainage patterns, and pollutes many water sources - (hydrosphere)

33. Distribution of volcanoes is not random • related to plate tectonics • commonly found along plate boundaries

35. Eruption types are a function of plate tectonic setting, magma composition and water/gas content.

36. Plinian eruption of Lascar Volcano in Chile

37. A Vulcanean eruption

38. Surtseyan eruption

39. Vesuvian eruption

40. Strombolian style eruption of Tungurahua Volcano, Ecuador

41. Eruption styles and their relative explosiveness * VEI stands for Volcanic Explosivity Index