Volcanoes II By: 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.com en.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 an block tributary streams an 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 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:+73,000 Victims:722 (ngdc.noaa.gov) Mount St. Helen (news.discovery.com) Damaged: S3 billion Victims: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