Volcanoes IIBy: Jericho C. Ventanilla

wagnerguatemala.weebly.com

Parts of a typical volcano(volcanochapter3.weebly.com)

Vent- also releases ash clouds, volcanic ashes, cinders, and bombs- divided into two parts:

- Central Vent – main- Side Vent – alternative

Conduit or Pipe- connects the magma chamber to the vent of the volcano- the purpose for this is to lead the magma to the vent and out to the surface

Crater- a depression at the central vent of the volcano shaped by volcanic activity- two types of crater:

- Summit – top- Flank – side

Caldera (en.wikipedia.org)- formed by the collapse of land, following a volcanic eruption

gaia3d.co.uk

marlimillerphoto.com

Three main types of volcanoes(geography.learnontheinternet.co.uk)

Shield Volcanoes - low with gentle sloping sides- from layers of lava- typically non-explosive- fatalities rarely occur - examples:

- Mount Kilauea (Hawaii, USA)- Mt Bulusan (local) (answers.com)

Composite Volcanoes (stratovolcanoes)- from layers of ash- explosive due of thick and high viscous lava- pose a threat to nearby life and property- examples:

- Mount St Helens (USA) - Mount Pinatubo (local)

Cinder cones (extremescience.com)- classic and cone-shaped peaks- eruptions are pretty small potatoes- small and hill-sized- examples (en.wikipedia.org):

- Paricutin (Mexico)- Mount Mayabobo (local)

conniemcarthur.com

markmaranga.com

paricutinmexico.weebly.com

movdata.net

Cesar C. Cambay/panoramio.comen.wikipedia.org

Dangers that volcanoes pose(en.wikipedia.org)

Nuée ardente (pyroclastic flow) Lahar (mudflow)Causes- fountain collapse- frothing- gravitational collapse- directional blast

Causes- snow and glaciers can be melted by lava - flood caused by glacier (glacier run)- water from crater lake, combined with volcanic material in an eruption- volcanic landslides

Effects- larger flow can travel for hundreds of kms- none on the scale have occurred for several hundred thousand years- kinetic energy of the moving boulders will flatten trees and buildings in their path

Effects (volcanoes.usgs.gov)- can lead of to increased deposition of sediment- can block tributary streams- can bury valleys and communities with debris

blog.mailasail.com

bgs.ac.uk

imgbuddy.com

photovolcanica.com

Volcanic landforms(w3.salemstate.edu)

Calderas- Crater Lake – violent eruptions accompanied by collapse- Hawaiian – subsidence after the magma supporting the summit seeks an alternative route- Yellowstone – largest with diameters ranging form 10 to 100 km

Fissure eruptions (volcano.si.edu) and basalt plateaus- produced extensive lava fields - fluid basaltic lava extruded from crustal fractures called fissures- examples:

- Columbia plateau- Deccan plateau

Volcanic pipes and necks- pipes connect a magma chamber to the surface- necks (e.g., Ship Rock, New Mexico) are resistant vents left standing after erosion has removed the volcanic cone

nvonews.com

hilo.hawaii.edu

yellowecho.com

Relationship between plate tectonics and volcanic activity Pacific Ring of Fire (worldatlas.com)

- notorious for volcanic eruptions- 450 volcanoes- approximately 75% of the world’s active volcanoes Volcanoes at convergent plate boundaries (en.wikipedia.org)- island arc

- archipelago- tectonically created arc-shaped mountain belts that are partly

below sea level- continental volcanic arc

- petrogenesis - partial melting of the subducting generates

primary magma- magmatism

- generate the primary magma Volcanism at divergent plate boundaries (ck12.org)- volcanoes erupt at mid-ocean ridge- the frequent volcanic eruptions are a result of hot spot activity and separating plates (kids-fun-science.com)Intraplate volcanism (geology.sdsu.edu)- mantle plume

- generated in the lower mantle- rise slowly through the mantle by convection

- hotspots - regions of voluminous volcanism

cbc.ca

geology.sdsu.edu

Living with volcanoes?

- 10% of the world's population lives in the vicinity of an active volcano (gtr.rcuk.ac.uk)- Agriculture (volcano.si.edu)

- provide soil nutrients- volcanic soils cover more than 1.5 million sq km

- Volcanic hazards (volcanology.geol.ucsb.edu)- Volcanic gas- Tsunamis- Volcanic Lighting

- Monitoring volcanic activities (volcanoes.usgs.gov)- important because could affect hundreds of thousands of people

Mount Pinatubo (1991) (newworldencyclopedia.org)Damaged:+73,000Victims:722 (ngdc.noaa.gov)

Mount St. Helen (news.discovery.com)Damaged: S3 billionVictims:57

Does volcanoes also change climate?

- The answer is YES- Once it gets into the stratosphere, sulphur dioxide from a volcano mingles with water, forming tiny sulphate particles (economist.com)- The cooling influence will dominate for the period immediately but the warming impact will last much longer (theguardian.com) - Examples(geology.sdsu.edu):

- Mt Tambora (1815) – 1816, year without summer- Mt St Helens (1980) – lowered temperature by 0.1 Celsius- El Chichon (1982) – lowered global temperature 3 to 5 times as much- Mt Pinatubo (1991) – decreased world temperatures by about 1 degree

Centigrade over the subsequent 2 years

Refrences• wagnerguatemala.weebly.com • volcanochapter3.weebly.com• gaia3d.co.uk• marlimillerphoto.com• geography.learnontheinternet.co.uk• answers.com• movdata.net• en.wikipedia.org• conniemcarthur.com• markmaranga.com• paricutinmexico.weebly.com• Cesar C. Cambay/panoramio.com• extremescience.com• volcanoes.usgs.gov• bgs.ac.uk• blog.mailasail.com• imgbuddy.com• photovolcanica.com• w3.salemstate.edu• volcano.si.edu• nvonews.com• hilo.hawaii.edu• yellowecho.com• worldatlas.com• cbc.ca• ck12.org• kids-fun-science.com• geology.sdsu.edu

• gtr.rcuk.ac.uk• volcanology.geol.ucsb.edu• newworldencyclopedia.org• ngdc.noaa.gov• news.discovery.com• economist.com• theguardian.com

Thank you for listening and I am open for questions