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Transcript of Volcanic Hazards
Remember plate tectonics?
Types of volcanoes
Volcanoes of the world: http://earth.rice.edu/mtpe/geo/geosphere/hot/volcanoes/volcanoes_b2.html
Big island: http://www.marinebio.net/marinescience/02ocean/hwgeo.htm
Prevolcano seismicity: http://thewatchers.adorraeli.com/2013/05/01/increased-activity-at-tungurahua-volcano/
Volcano profiles: http://geogblogstudents.blogspot.com/2012/03/natural-hazards-geog3.html
Explosivity index: http://en.wikipedia.org/wiki/Volcanic_Explosivity_Index
Subduction profile: http://journals.hil.unb.ca/journalimages/GEOCAN/2006/Vol_33/No_04/geocan33_4ser01_fig3.jpg
Decompression melting: http://geochemistry.usask.ca/Bill/Courses/GOL%20101/HTML%20Presentation%20folder/Igneous%20Rocks/sld043.htm
Hot spot: http://www.geo.arizona.edu/geo5xx/geos577/projects/knutson/Hot%20Spot.htm
Krakatoa tsunami: http://volcano.oregonstate.edu/tsunamis
Volcano deformation: http://info.geonet.org.nz/display/volc/Monitoring+Methods
Divergent plate boundaries
"Hot spots" not associated with narrow zones of deformation
Lava and water
Eruptions and debris flows
Just how good is prediction?
What do you think?
Write down what you know about volcanoes
What do you know now?
Take a moment to look at what you had written in the beginning and change or add some understandings.
Ground deformation (GPS, tilt meters)
Seismic activity (seismometers)
Magma resonance (seismometers)
In 2000, 30,000 people evacuated from a a nearby volcano in Mexico, just prior to its erutpion.
24 October 2014
Cerro Negro (Columbia-Ecuador border)
4,300 earthquakes in a 24 hour period (many M4)
Local water sources contaminated by iron and sulfur
No good historical record
Evacuation of nearby 12,000 people
Explosive (phreatic) eruptions
Can form sufuric acid steam and hydrochloric acid steam
Seventy years ago, on May 10, 1924, a violent phreatic (steam) eruption began in Halema'uma'u that sent repeated columns of ash high into the sky. The explosions continued for 18 days, with the largest occurring on May 18. The steam explosions hurled rocks as large as eight tons as far as 0.6 miles from the crater; these blocks still surround Halema'uma'u. One of these blocks fatally injured a Mr. Taylor, who approached too close to the crater to take a photograph. The explosion that killed Mr. Taylor generated a 6,000-foot-tall column of ash.
Lake Nyos, Camaroon, 1986
1.6 cu km carbon dioxide gas
Carbon dioxid is not a poison
It is silent and scentless
Foces the oxygen out of the area
Suffocated 1800 people, 3500 livestock
large volumes of CO2 expelled from volcanic crater