1Volcanoes and Volcanic ActivityLocations of relatively young volcanoes in North AmericaRelationship between volcanism and plate tectonicsTypes of volcanic eruptions and hazards1Types of volcanic eruptions and hazardsTypes of volcanoes and related landformsVolcano monitoring: looking for signs that a volcano may be about to eruptCurrent volcanic activity & status: http://volcanoes.usgs.gov/2Locations and Origin of Volcanic ActivityMost volcanism occurs at divergent plate boundaries (ocean ridges and continental rifts), convergent boundaries (subduction zones), and hot spots.3This Dynamic Planet - USGSVolcanism at ocean ridges and oceanic hot spots primarily results in mafic (basaltic) rocks. Volcanism at continental rift zones and continental hot spots produces a broad range of igneous rock compositions. Subduction zones primarily result in intermediate (andesitic) and mafic rocks with lesser amounts of felsic rocks.Styles of volcanic eruptionsEffusive - lava flowsPyroclastic - explosive eruptions that produce airborne fragments of lavaAn effusive eruption of basaltic lava in Hawaii - NASAA large pyroclastic eruption of Klyuchevskaya Volcano, Kamchatka Peninsula, Russia in October 1994NASA STS068-214-0434http://www.youtube.com/watch?v=K9iZd6wzlCk&feature=relatedSome features produced by effusive eruptionsPahoehoe and aa lava flowsLava tubes Columnar fracturesPillow lavasFi ti5Fissure eruptionsLava domesObsidian flowsLava flow hazardsAa (jagged) and pahoehoe (smooth, wrinkled/ropy) lavasUSGS6Fig 5.3 Understanding EarthUSGSPahoehoe http://www.youtube.com/watch?v=xK2WGBn8Ojs&feature=related2Devil’s Post Pile N. Mon., Columnar jointing (fractures) in lava flows7Columns near White Pass, Washington-S. Kuehn,CaliforniaCh 4 Understanding Earth15 million year old pillow lavas and lava flow, part of the Columbia River basalts in WashingtonPillow lavaproduced by lava flows under waterFig 3.2 Understanding Earth8http://www.youtube.com/watch?v=gn_IW5Vsxawhttp://www.youtube.com/watch?v=xsJn8izcKtg9fissure_vent-img0001.jpgLava domes: Mt. St. Helens lava dome in 1992 (top) and Novarupta lava dome, Alaska (bottom)10USGSS. KuehnPhotos of the growing lava dome at Mt. St. Helens:http://vulcan.wr.usgs.gov/Volcanoes/MSH/Eruption04/Monitoring/sugarbowl_remote_camera_10-04_to_09-05.htmlhttp://vulcan.wr.usgs.gov/Volcanoes/MSH/Images/MSH04/framework.htmlLava domes are usually formed by felsic to intermediate lava (ryholite and dacite) because these lavas have a high viscosity and don’t flow very well.A lava flow entering a populated area in HawaiiBasaltic lava can flow long distances because of its low viscosity.11USGS 2553015_L.jpgLava covers Kalapana, Hawaii23 April 199012See:http://hvo.wr.usgs.gov/kilauea/history/1990Kalapana/6 June 199013 June 19903Some features and products of pyroclastic eruptionsLava fountainsStrombolian explosionsEruption columnsPyroclastic flows Tephra 13Hazards of pyroclastic eruptionsAsh and pumice fall (tephra fall) hazardsPyroclastic flow and blast hazardsLava fountain from Pu’u O’o at Kilauea volcano, Hawaii14Next: lava fountain video clip15http://www.youtube.com/watch?v=OowFvnlWI90&feature=relatedPhoto: Strombolian explosion from a cinder cone at Veniaminof volcano, Alaska in 1983 USGS DDS-40-IMG0052.jpg16Strombolian eruption at Stromboli Volcano, Italy - The incandescent lava fragments generally consist of partially molten volcanic bombs that become rounded as they fly through the air. USGS photoglossary - Photo by B. Chouet in 1969Next: strombolian video clipPlinian Plinian Eruption Eruption ColumnColumnEruption cloudEruption cloudWindWindTephraTephra fall fall (pumice & ash)(pumice & ash)Large Large BombsBombsMt St Helens ash cloud May 18, 1980 -Austin PostMt. St. Helens airfall tephra distribution and path of the May 18, 1980 eruption cloudFig. 8.26c Keller, Environmental Geology18USGS419Mt. St. Helens ash cloud approaching Ephrata, WA on May 18, 1980. Ephrata is about 145 miles from Mt. St. Helens. The ash cloud arrived in less than 3 hours. USGS Fact Sheet 027-00 Photo by Douglas MillerNext: Mt St. Helens eruption cloud and ash fall video clipAshfall from Mt. Spur in 1992USGSOFR93707 i 15 j20USGS OFR93-707 img15.jpg21Major air-routes in the north PacificUSGS Fact Sheet 030_97Small, basaltic volcanic bombs - Note the aerodynamic shapesUSGS bombs-30410914-028_large.JPG22A very large, felsic bread crust bomb23Pyroclastic flow at Mt St HelensOne of at least 17 flows which rushed down the side of the volcano on May 18, 1980. USGSPyroclastic flow at Augustine Volcano, Alaska in 1986 USGSAftermath of a pyroclastic flow (1998)Soufriere Hills volcano, MontserratCh 5 Understanding Earth24Reinforced concrete broken by a pyroclastic flow- USGS5Mt. St. Helens before and after May 18, 198025USGS MSH vol1 IMG0003.jpgUSGS MSH vol1 IMG0045.jpgNext: landslide and blast video clipCloser view of the hummocks at Mt. St. Helens– Similar but larger features are present along Interstate 5 west of Mt. ShastaJuly, 2003 - S. Kuehn26Large tree ripped apart by the force of the lateral blast at Mt. St. Helens27USGS CVO CD2 IMG0006.jpgDamage from lateral blastMt. St. Helens, 1980USGS MSH Vol1 IMG001.jpg28Lahars (volcanic mudflows) from Mt St. Helens damaged many homes, shut down Interstate-5, and blocked shipping on the Columbia River29Mt St. Helens lahar damage USGS MSH vol1 IMG0087.jpgDevastation of a small town caused by a lahar from Mt Pinatubo in the Philippines30PhilippinesUSGS 30410135_029_large.jpgMore about lahars:http://volcanoes.usgs.gov/Products/Pglossary/lahar.html6Volcanic hazardsSummary:• Lava flow hazards• Ash and pumice fall (tephra fall) hazards•Pyroclastic flow 31USGSyhazards• Landslide/volcano collapse hazards• Volcanic blasts• Volcanic gases• Lahar/flood hazardshttp://volcanoes.usgs.gov/hazards/Some types of volcanoes and related landformsShield volcanoesComposite volcanoes (also known as stratovolcanoes)Cinder cones32CalderasFlood basaltsOceanic crustExplosion craters and maars33Two shield volcanoesTop: Mauna Loa volcano, Hawaii –USGSBottom: Newberry volcano, Oregon –S. KuehnOlympus Mons shield volcano, Mars – Olympus Mons is the largest known volcano in the solar system. It is about 550 km (350 mi) across and about 25 km (16 mi) high with a 65 km (40 mi) wide caldera at the summit. It is more than 4 times wider than Mauna Loa, the largest volcano on Earth.34A composite or stratovolcano: Mt. Rainier, WashingtonS. Kuehn