Volcanoes and Volcanic Rocks IIPowerPoint PresentationSlide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33SHV Dome - Dec. 2002Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Kinematic Flow ModelsRequired dataSlide 46Tar River Valley, Spring 1996Simulated Flow VelocitiesSHV Pyroclastic Deposits to 1998New Tar River DeltaVolcanoes and Volcanic Rocks IIVolcanoes and Volcanic Rocks IIPhoto credit: G. Mattiolitypes of volcanoes• shield volcanoesreflect magma composition (silica content)• cinder cones• composite volcanoes• volcanic domesnote steepness of volcano sidesvolcano type and size relative to central ventshield volcanoes are by far the largestshield volcanoes: low and broad (like a shield)QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.gently-slopingbuilt by low-viscosity lava flows(basalts)summit of Mauna LoaQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.shield volcanoes: built by lava flowssolidified layers of lavaeruptions from central vent (summit caldera)(may form lava lakes)flank (sides of volcano)(may form ribbons of lava)Magma ChamberQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.lava lake in the summit calderaQuickTime™ and aH.264 decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.flank eruption: through a fissure (crack)fire fountaining during flank eruptionflow of lava down the slope can make tubesQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.-- outside of flow cools; solidifies-- inside of flow still flowingbasaltic flows of two types: pahoehoe (ropy)QuickTime™ and aH.264 decompressorare needed to see this picture.QuickTime™ and aH.264 decompressorare needed to see this picture.blocky flows: aaQuickTime™ and aH.264 decompressorare needed to see this picture.• temperature as high as 1175°C (2150°F)• pahoehoe and aa -- depends on gas contentaa farther from vent (lava degassed)• speed downslope may exceed 30 km/hrcharacteristics of basaltic flows (Hawaii)formation of spatter coneQuickTime™ and aH.264 decompressorare needed to see this picture.shield volcanoes on other planetsOlympus Mons on Marswhat happens when basalt flow cools?cools toward center point of hexagonsforms “columns” in three dimensionsover a given area…QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.columnar jointingDevil’s Tower, WyomingQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.cinder cones: small, steeply slopingcomposed of a pile of loose cinders (2-64 mm in size)--mostly basaltic--QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.composite volcanoes: mixtures of typescomposed of layers of both pyroclastic debris and solidified lava flows -- andesite -- intermediate silica contentcomposite volcanoesQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.• moderate to steeply sloping• most common type at convergent plate boundaries (think about igneous processes from lectures 4 and 5)QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.Popocatepetl, MexicoQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.Mt. Hood, Oregonvolcanic domeshigh silica content; high viscosityfelsic lavas -- often glassy (obsidian)volcanic domesQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.Mt. Lassen, a plug domedome in Mt. St. Helens craterPhoto of dome in Dec. 02 on a rare clear day. By July 2003 the dome had grown to >230 M m3 and had not collapsed significantly for 2 years!!SHV Dome - Dec. 2002Photo credit: G. Mattioliother types of eruptionssubmarine eruptions• basaltic• eruptions along mid-ocean ridge• most voluminousQuickTime™ and aVideo decompressorare needed to see this picture.“pillow basalts”QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.distribution of mid-ocean ridges (basaltic volcanism)other types of eruptionsflood basalt• forms lava plateaus• coincides with extinctions• erupts high volume of very fluid lavaQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.Deccan trapsIndiaQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.now, a bit of a recap…importance of silica content (viscosity)ash clogs jet enginesPacific air routes and volcanoesbefore we leave the subject: a couple of other hazards of volcanoes…QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.lahars: mud flowsQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.November 13, 198523,000 people killed by lahargenerated from a small eruption--snow melts--Nevada del RuizQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.village of Armero70 km from summitQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.town was in center ofimage to rightKinematic Flow Models•Theoretical background - “sliding block” on inclined plane with friction.•Data required•Parameterization of the models•Results from Montserrat•ImplicationsRequired data•Accurate DEM’s - required adding a synthetic dome to generate current topopgraphy not on available maps•Previous direct measurements at other similar volcanoes: Mt. St. Helen’s and Mt. UnzenKinematic Flow ModelsFrom: Hooper & Mattioli, 2001Tar River Valley, Spring 1996Photo credit: G. MattioliBurnt Zone - Initial channelization of small PF’sSimulated Flow VelocitiesFrom: Hooper & Mattioli, 2001SHV Pyroclastic Deposits to 1998New