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http://volcano.und.nodak.edu/volcanoes.html BIG BOOMS! Volcanoes and Earthquakes Earth2Class Workshops for Teachers Lamont-Doherty Earth Observatory Originally presented 20 November 2004 Guest Scientists: Art Lerner-Lam Steve Goldstein http://volcano.und.nodak.edu/vwdocs/msh/ov/ova/ovaldsl.html Volcanoes • The main focus of today’s workshop will be VOLCANOES • Recent activity at Mt. St. Helens in southern Washington has raised interest in volcanic activity within the continental United States • The LDEO campus lies atop the Palisades Sill, remnant of igneous activity 195 MYA +/- Volcanic Activity by Land and Sea • We tend to be aware of the continental volcanoes, but of course most crustal lava forms the ocean floors • The Mid-Ocean Ridge is basaltic flows, with islands rising above the sea surface in various locations • Scattered through the ocean basins, especially in the Pacific, are hundreds of seamounts and guyots Mapping the Sea Floors in Detail • Modern technologies, such as side-scan sonars, create maps of the ocean floors in much greater detail than previously possible. • Here is a section of the East Pacific Rise and nearby seamounts. http://pubs.usgs.gov/publications/text/topomap.html A Major Surprise in the Deep! The most spectacular discovery about mid- ocean ridge lava flows was made in 1977 when “black smokers” – hydro- thermal vents rich in sulphide minerals – were first observed by the “Alvin.” http://www.amnh.org/nationalcenter/expeditions/blacksmokers/black_smokers.html The Hawaiian Islands are some of the largest volcanoes on Earth. This image showing Mauna Kea (MK), Mauna Loa (ML), Hualalai (H), and Kohala (K) was taken from near the summit of East Maui volcano. These are SHIELD VOLCANOES, which form from a fluid Lava that solidifies to form basalt. For more about shield volcanoes, go to: http://volcano.und.nodak.edu/vwdocs/vwlessons/volcano_types/shield.htm Stratovolcanoes This is Arenal in Costa More than 60% of all Rica, a volcano volcanoes are almost always in STRATOVOLCANOES. eruption. These consist of andesite or other lavas that are cooler and more viscous than basalt lavas, interlayered with pyroclastic materials. http://volcano.und.nodak.edu/vwdocs/vwlessons/volcano_types/strato.htm CINDER CONES A third type of volcano involves cones built mainly of cinders and ash. One of the most famous is Paricutin, Mexico, which was observed from its beginning in 1943. http://volcano.und.nodak.edu/vwdocs/volc_tour/mex/10Paricutin.html Flood Basalts • At times in the Earth’s history, vast amounts of lava have spewed out onto the surface, covering thousands of sq. km. with “flood basalts.” • The Columbia Flood Basalt in the Pacific NW is the US’ largest http://www.geolsoc.org.uk/template.cfm?name=fbasalts Where do volcanoes exist? On every continent! Here is a link where you can find images of volcanoes from almost every continent: http://volcano.und.nodak.edu/vwdocs/volc_images/volc_images.html Much of Antarctica is volcanic, including Mt. Erebus, the southernmost volcano http://www.ees.nmt.edu/Geop/mevo/mevo.html Volcanoes at the Top of the World Young volcanoes have been identified in the East Gakkel Ridge of the Arctic Ocean by bathymetric surveys conducted from a submarine in 1999. The Arctic Mod-Ocean Ridge Expedition (AMORE) in 2001 explored more than a thousand km of this feature. http://www.ldeo.columbia.edu/edu/eesj/gradpubs/web_pub/CRgeotimes 012403.pdf Where Are Volcanoes Erupting Now? One of the best sources for information for current volcanic activity is maintained by the USGS/Smithsonian Institution’s Global Volcanism Program http://www.volcano.si.edu/reports/usgs/index.cfm What’s the Link between Volcanoes and Earthquakes? • Comparison of the distribution patterns of volcanoes and earthquakes show much overlap, as the next slide shows. • Both occur primarily at plate boundaries. • A few volcanoes occur at “Hot Spots” or mark where such features once were located. http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/volcanic_landforms/volcano_distribution.html http://www.uwsp.edu/geo/faculty/ritter/images/lithosphere/tectonics/Vol_eq_plates_GSFC.gif Examples of Pertinent Core Concepts (PS/ES) • 2.1a. Earth systems have internal and external sources of energy, both of which create heat. • 2.1b. The transfer of heat energy within Earth's interior results in the formation of regions of different densities. These density differences result in motion. • 2.1n. Many of Earth's surface features are the consequence of forces associated with plate motion and interaction. These include: mid-ocean ridges/rifts; subduction zones trenches/island arcs; mountain ranges (folded, faulted, and volcanic); hot spots; and the magnetic and age patterns in surface bedrock. • 2.1l. The lithosphere consists of separate plates that ride on the more fluid asthenosphere and move slowly in relationship to one another, creating convergent, divergent, and transform plate boundaries. These motions indicate Earth is a dynamic geologic system. > These plate boundaries are the sites of most earthquakes, volcanoes, and young mountain ranges. > Compared to continental crust, ocean crust is thinner and denser. New ocean crust continues to form at mid-ocean ridges. > Earthquakes and volcanoes present geologic hazards to humans. Loss of property, personal injury, and loss of life can be reduced by effective emergency procedures. Teaching about Volcanoes • Volcano World The best web site for teaching and learning about volcanoes was created by the University of North Dakota. http://volcano.und.nodak.edu/vw.html USGS The USGS also provides great information, images, and lessons. http://volcanoes.usgs.gov/ Volcanoes are Well-Suited to Hands-on Activities Here are links to some examples: • Scott Johnson (Grand Forks, ND) has created many fine lessons for Volcano World. Two examples are “Erupting Volcano” and “Lava Dome Building” http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Ch2CM/Handson5V olcanoes.html • USGS/Cascades Volcano Observatory has developed some nice lessons, including a variety of paper models http://vulcan.wr.usgs.gov/Outreach/FunStuff/framework.html Following a break, we will learn more about the science and skill of investigating volcanoes from Art Lerner-Lam and Steve Goldstein.
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