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 Composite Volcanoes (stratovolcanoes) Cinder cones (extremescience.com) - low with gentle sloping sides - from layers of ash - classic and cone-shaped peaks - from layers of lava - explosive due of thick and high viscous lava - eruptions are pretty small potatoes - typically non-explosive - pose a threat to nearby life and property - small and hill-sized - fatalities rarely occur - examples: - examples (en.wikipedia.org): - examples: - Mount St Helens (USA) - Paricutin (Mexico) - Mount Kilauea (Hawaii, USA) - Mount Pinatubo (local) - Mount Mayabobo (local) - Mt Bulusan (local) (answers.com) movdata.net en.wikipedia.org conniemcarthur.com markmaranga.com paricutinmexico.weebly.com Cesar C. Cambay/panoramio.com Dangers that volcanoes pose (en.wikipedia.org) Nuée ardente (pyroclastic flow) Causes - fountain collapse - frothing - gravitational collapse - directional blast bgs.ac.uk 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 blog.mailasail.com Lahar (mudflow) 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 (volcanoes.usgs.gov) imgbuddy.com - can lead of to increased deposition of sediment - can block tributary streams - can bury valleys and communities with debris 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 nvonews.com hilo.hawaii.edu 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 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:+73,000 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