Pyroclastic Flow ×
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Volcanic Ash and Aviation Safety: Proceedings of the First International Symposium on Volcanic Ash and Aviation Safety
Volcanic Ash and Aviation Safety: Proceedings of the First International Symposium on Volcanic Ash and Aviation Safety Edited by Thomas J. Casadevall U.S. GEOLOGICAL SURVEY BULLETIN 2047 Proceedings of the First International Symposium on Volcanic Ash and Aviation Safety held in Seattle, Washington, in July I991 @mposium sponsored by Air Line Pilots Association Air Transport Association of America Federal Aviation Administmtion National Oceanic and Atmospheric Administration U.S. Geological Survey amposium co-sponsored by Aerospace Industries Association of America American Institute of Aeronautics and Astronautics Flight Safety Foundation International Association of Volcanology and Chemistry of the Earth's Interior National Transportation Safety Board UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1994 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Gordon P. Eaton, Director For sale by U.S. Geological Survey, Map Distribution Box 25286, MS 306, Federal Center Denver, CO 80225 Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S.Government Library of Congress Cataloging-in-Publication Data International Symposium on Volcanic Ash and Aviation Safety (1st : 1991 Seattle, Wash.) Volcanic ash and aviation safety : proceedings of the First International Symposium on Volcanic Ash and Aviation Safety I edited by Thomas J. Casadevall ; symposium sponsored by Air Line Pilots Association ... [et al.], co-sponsored by Aerospace Indus- tries Association of America ... [et al.]. p. cm.--(US. Geological Survey bulletin ; 2047) "Proceedings of the First International Symposium on Volcanic Ash and Aviation Safety held in Seattle, Washington, in July 1991." Includes bibliographical references. -
(2000), Voluminous Lava-Like Precursor to a Major Ash-Flow
Journal of Volcanology and Geothermal Research 98 (2000) 153–171 www.elsevier.nl/locate/jvolgeores Voluminous lava-like precursor to a major ash-flow tuff: low-column pyroclastic eruption of the Pagosa Peak Dacite, San Juan volcanic field, Colorado O. Bachmanna,*, M.A. Dungana, P.W. Lipmanb aSection des Sciences de la Terre de l’Universite´ de Gene`ve, 13, Rue des Maraıˆchers, 1211 Geneva 4, Switzerland bUS Geological Survey, 345 Middlefield Rd, Menlo Park, CA, USA Received 26 May 1999; received in revised form 8 November 1999; accepted 8 November 1999 Abstract The Pagosa Peak Dacite is an unusual pyroclastic deposit that immediately predated eruption of the enormous Fish Canyon Tuff (ϳ5000 km3) from the La Garita caldera at 28 Ma. The Pagosa Peak Dacite is thick (to 1 km), voluminous (Ͼ200 km3), and has a high aspect ratio (1:50) similar to those of silicic lava flows. It contains a high proportion (40–60%) of juvenile clasts (to 3–4 m) emplaced as viscous magma that was less vesiculated than typical pumice. Accidental lithic fragments are absent above the basal 5–10% of the unit. Thick densely welded proximal deposits flowed rheomorphically due to gravitational spreading, despite the very high viscosity of the crystal-rich magma, resulting in a macroscopic appearance similar to flow- layered silicic lava. Although it is a separate depositional unit, the Pagosa Peak Dacite is indistinguishable from the overlying Fish Canyon Tuff in bulk-rock chemistry, phenocryst compositions, and 40Ar/39Ar age. The unusual characteristics of this deposit are interpreted as consequences of eruption by low-column pyroclastic fountaining and lateral transport as dense, poorly inflated pyroclastic flows. -
Source to Surface Model of Monogenetic Volcanism: a Critical Review
Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021 Source to surface model of monogenetic volcanism: a critical review I. E. M. SMITH1 &K.NE´ METH2* 1School of Environment, University of Auckland, Auckland, New Zealand 2Volcanic Risk Solutions, Massey University, Palmerston North 4442, New Zealand *Correspondence: [email protected] Abstract: Small-scale volcanic systems are the most widespread type of volcanism on Earth and occur in all of the main tectonic settings. Most commonly, these systems erupt basaltic magmas within a wide compositional range from strongly silica undersaturated to saturated and oversatu- rated; less commonly, the spectrum includes more siliceous compositions. Small-scale volcanic systems are commonly monogenetic in the sense that they are represented at the Earth’s surface by fields of small volcanoes, each the product of a temporally restricted eruption of a composition- ally distinct batch of magma, and this is in contrast to polygenetic systems characterized by rela- tively large edifices built by multiple eruptions over longer periods of time involving magmas with diverse origins. Eruption styles of small-scale volcanoes range from pyroclastic to effusive, and are strongly controlled by the relative influence of the characteristics of the magmatic system and the surface environment. Gold Open Access: This article is published under the terms of the CC-BY 3.0 license. Small-scale basaltic magmatic systems characteris- hazards associated with eruptions, and this is tically occur at the Earth’s surface as fields of small particularly true where volcanic fields are in close monogenetic volcanoes. These volcanoes are the proximity to population centres. -
Chapter 2 Alaska’S Igneous Rocks
Chapter 2 Alaska’s Igneous Rocks Resources • Alaska Department of Natural Resources, 2010, Division of Geological and Geophysical Surveys, Alaska Geologic Materials Center website, accessed May 27, 2010, at http://www.dggs.dnr.state.ak.us/?link=gmc_overview&menu_link=gmc. • Alaska Resource Education: Alaska Resource Education website, accessed February 22, 2011, at http://www.akresource.org/. • Barton, K.E., Howell, D.G., and Vigil, J.F., 2003, The North America tapestry of time and terrain: U.S. Geological Survey Geologic Investigations Series I-2781, 1 sheet. (Also available at http://pubs.usgs.gov/imap/i2781/.) • Danaher, Hugh, 2006, Mineral identification project website, accessed May 27, 2010, at http://www.fremontica.com/minerals/. • Digital Library for Earth System Education, [n.d.], Find a resource—Bowens reaction series: Digital Library for Earth System Education website, accessed June 10, 2010, at http://www.dlese.org/library/query.do?q=Bowens%20reaction%20series&s=0. • Edwards, L.E., and Pojeta, J., Jr., 1997, Fossils, rocks, and time: U.S. Geological Survey website. (Available at http://pubs.usgs.gov/gip/fossils/contents.html.) • Garden Buildings Direct, 2010, Rocks and minerals: Garden Buildings Direct website, accessed June 4, 2010, at http://www.gardenbuildingsdirect.co.uk/Article/rocks-and- minerals. • Illinois State Museum, 2003, Geology online–GeoGallery: Illinois State Museum Society database, accessed May 27, 2010 at http://geologyonline.museum.state.il.us/geogallery/. • Knecht, Elizebeth, designer, Pearson, R.W., and Hermans, Majorie, eds., 1998, Alaska in maps—A thematic atlas: Alaska Geographic Society, 100 p. Lillie, R.J., 2005, Parks and plates—The geology of our National parks, monuments, and seashores: New York, W.W. -
Anatomy of a Volcanic Eruption: Case Study: Mt. St. Helens
Anatomy of a Volcanic Eruption: Case Study: Mt. St. Helens Materials Included in this Box: • Teacher Background Information • 3-D models of Mt. St. Helens (before and after eruption) • Examples of stratovolcano rock products: Tuff (pyroclastic flow), pumice, rhyolite/dacite, ash • Sandbox crater formation exercise • Laminated photos/diagrams Teacher Background There are several shapes and types of volcanoes around the world. Some volcanoes occur on the edges of tectonic plates, such as those along the ‘ring of fire’. But there are also volcanoes that occur in the middle of tectonic plates like the Yellowstone volcano and Kilauea volcano in Hawaii. When asked to draw a volcano most people will draw a steeply sided, conical mountain that has a depression (crater) at the top. This image of a 'typical' volcano is called a stratovolcano (a.k.a. composite volcano). While this is the often visualized image of a volcano, there are actually many different shapes volcanoes can be. A volcano's shape is mostly determined by the type of magma/lava that is created underneath it. Stratovolcanoes get their shape because of the thick, sticky (viscous) magma that forms at subduction zones. This magma/lava is layered between ash, pumice, and rock fragments. These layers of ash and magma will build into high elevation, steeply sided, conical shaped mountains and form a 'typical' volcano shape. Stratovolcanoes are also known for their explosive and destructive eruptions. Eruptions can cause clouds of gas, ash, dust, and rock fragments to eject into the atmosphere. These clouds of ash can become so dense and heavy that they quickly fall down the side of the volcanoes as a pyroclastic flow. -
A Mineralogy of Anthropocene E
1 A Minerology for the Anthropocene Pierre FLUCK Institut Universitaire de France / Docteur-ès-Sciences / geologist and archeologist / Emeritus Professor at Université de Haute-Alsace This essay is a follow-up on « La signature stratigraphique de l’Anthropocène », which is also available on HAL- Archives ouvertes. Table of contents 1. Introduction: neoformation minerals in ancient mining galleries 2. Minerals from burning coal mines 3. Minerals from the mineral processing industry 4 ...and metallurgy 5. Neoformations in slags 6. Speciation of heavy metals in soils 7. Metal objects in their archaeological environment, or affected by fire 8. Neoformations in or on the surface of building stones 9. A mineralogy of materials. The “miracle of the potter”. The minerals in cement 10. A mineralogy of the biosphere? Conclusions Warning. This paper is written to be read by both specialists and a wider audience. However, it contains many mineral names. While these may resonate in the minds of mineralogists or collectors, they may not be as meaningful to less discerning readers. Such readers should not be scared, for they may find excellent encyclopaedic records on the web, including chemical composition, crystallographic properties and description of each of these species. This is why we have decided not to include further information in this paper. Acknowledgements. I would like to thank the mineralogists with whom I have had the opportunity to maintain fruitful exchanges for a long time: my pupil Hubert Bari, Éric Asselborn, Cédric Lheur, François Farges. And I would like to honour the memories of René Weil (1901-1983), my master in descriptive mineralogy, and of Jacques Geffroy (1918-1993), pupil of Alfred Lacroix, my master in metallogeny. -
Pyroclastic Flow Hazards
Pyroclastic Flow Hazards Lecture Objectives -definition and characteristics -generation of pyroclastic flows -impacts and hazards What are pyroclastic flows? Pyroclastic flows are high- density mixtures of hot, dry rock fragments and hot gases that move away from the vent that erupted them at high speeds. Generation Mechanisms: -explosive eruption of molten or solid rock fragments, or both. -non-explosive eruption of lava when parts of dome or a thick lava flow collapses down a steep slope. Most pyroclastic flows consist of two parts: a basal flow of coarse fragments that moves along the ground, and a turbulent cloud of ash that rises above the basal flow. Ash may fall from this cloud over a wide area downwind from the pyroclastic flow. Mt. St. Helens Effects of pyroclastic flows A pyroclastic flow will destroy nearly everything in its path. With rock fragments ranging in size from ash to boulders traveling across the ground at speeds typically greater than 80 km per hour, pyroclastic flows knock down, shatter, bury or carry away nearly all objects and structures in their way. The extreme temperatures of rocks and gas inside pyroclastic flows, generally between 200°C and 700°C, can cause combustible material to burn, especially petroleum products, wood, vegetation, and houses. Pyroclastic flows vary considerably in size and speed, but even relatively small flows that move <5 km from a volcano can destroy buildings, forests, and farmland. On the margins of pyroclastic flows, death and serious injury to people and animals may result from burns and inhalation of hot ash and gases. Pyroclastic flows generally follow valleys or other low-lying areas and, depending on the volume of rock debris carried by the flow, they can deposit layers of loose rock fragments to depths ranging from less than one meter to more than 200 m. -
The Science Behind Volcanoes
The Science Behind Volcanoes A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot magma, volcanic ash and gases to escape from the magma chamber below the surface. Volcanoes are generally found where tectonic plates are diverging or converging. A mid-oceanic ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by divergent tectonic plates pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by convergent tectonic plates coming together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can also form where there is stretching and thinning of the Earth's crust in the interiors of plates, e.g., in the East African Rift, the Wells Gray-Clearwater volcanic field and the Rio Grande Rift in North America. This type of volcanism falls under the umbrella of "Plate hypothesis" volcanism. Volcanism away from plate boundaries has also been explained as mantle plumes. These so- called "hotspots", for example Hawaii, are postulated to arise from upwelling diapirs with magma from the core–mantle boundary, 3,000 km deep in the Earth. Erupting volcanoes can pose many hazards, not only in the immediate vicinity of the eruption. Volcanic ash can be a threat to aircraft, in particular those with jet engines where ash particles can be melted by the high operating temperature. Large eruptions can affect temperature as ash and droplets of sulfuric acid obscure the sun and cool the Earth's lower atmosphere or troposphere; however, they also absorb heat radiated up from the Earth, thereby warming the stratosphere. -
Respicite Astra: a Historic Journey in Astronomy Through Books
0 Respicite Astra: A Historic Journey in Astronomy through Books RReessppiicciittee AAssttrraa A Historic Journey in Astronomy through Books The Astronomiicall Sociiety of Mallta The Natiionall Liibrary of Mallta The Astronomical Society of Malta The National Library of Malta 1 Respicite Astra: A Historic Journey in Astronomy through Books Respicite Astra A Historic Journey in Astronomy through Books Exhibition held between 25 September – 18 October 2010-09-21 at the National Library, Valletta, Malta on the occasion of Notte Bianca 2010 Introductory Text Mr Victor Farrugia Captions Mr Leonard Ellul Mercer – Pgs 23-24, 57 Mr Alexander Pace – Pgs 25-26, 58, 63, 70 Prof Frank Ventura – Pgs 4, 6-13, 15-18, 21, 27-31, 33, 35-38, 40, 42- 43, 45-48, 50-56, 60-62, 65-69, 72-76, 80, 85, 87, 93 Acknowledgements The Committee of the Astronomical Society of Malta would like to acknowledge the following persons for their kind and generous help in setting up this Exhibition at the Main Hall of the National Library starting on 25th September 2010 during the Notte Bianca event: Mr Fabio Agius (MaltaPost Philatelic Archives) Ms C Michelle Buhagiar (National Library of Malta) Ms Maroma Camilleri National Library of Malta) Mr Leonard Ellul Mercer (Personal capacity) Victor Farrugia (Astronomical Society of Malta) Mr Alexander Pace (Astronomical Society of Malta) Arch Alexei Pace (Astronomical Society of Malta) Ms Joanne Sciberras (National Library of Malta) Mr Tony Tanti (Astronomical Society of Malta) Prof Frank Ventura (University of Malta) Staff of the National Library of Malta Front Image Great Orion Nebula by Mr Leonard Ellul Mercer Production The Astronomical Society of Malta P.O. -
Volcanic Eruptions
Volcanic Eruptions •Distinguish between nonexplosive and explosive volcanic eruptions. • Identify the features of a volcano. • Explain how the composition of magma affects the type of volcanic eruption that will occur. • Describe four types of lava and four types of pyroclastic material. I. Volcanic Eruptions A. A volcano is a vent or fissure in the Earth’s surface through which molten rock and gases are expelled. B. Molten rock is called magma. C. Magma that flows onto the Earth’s surface is called lava. II. Nonexplosive Eruptions A. Nonexplosive eruptions are the most common type of volcanic eruptions. These eruptions produce relatively calm flows of lava in huge amounts. B. Vast areas of the Earth’s surface, including much of the sea floor and the Northwestern United States, are covered with lava form nonexplosive eruptions. Kilauea Volcano in Hawaii Island III. Explosive Eruptions A. While explosive eruptions are much rarer than non-explosive eruptions, the effects can be incredibly destructive. B. During an explosive eruption, clouds of hot debris, ash, and gas rapidly shoot out from a volcano. C. An explosive eruption can also blast millions of tons of lava and rock from a volcano, and can demolish and entire mountainside. Alaska's Mount Redoubt eruption in March 2009 IV. What Is Inside a Volcano? A. The interior of a volcano is made up of two main features. B. The magma chamber is the body of molten rock deep underground that feeds a volcano. C. The vent is an opening at the surface of the Earth through which volcanic material passes. -
Geological Mapping, Structural Setting and Petrographic Description of the Archean Volcanic Rocks of Mnanka Area, North Mara
PROCEEDINGS, 43rd Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, February 12-14, 2018 SGP-TR-213 Geological Mapping, Structural Setting and Petrographic Description of the Archean Volcanic Rocks of Mnanka Area, North Mara Ezra Kavana Acacia Mining PLc, North Mara Gold Mine, Department of Geology, P. O. Box 75864, Dar es Salaam, Tanzania Email: [email protected] Keywords: Musoma Mara Greenstone Belt, Mnanka volcanics, Archaean rocks and lithology ABSTRACT The Mnanka area is situated within the Musoma Mara Greenstone Belt, the area is near to Nyabigena, Gokona and Nyabirama gold mines. Mnanka area comprises of the sequence of predominant rhyolitic volcanic rocks, chert and metasediments. Gold mineralizations in Mnanka area is structure controlled and occur mainly as hydrothermal disseminated intrusion related deposits. Hence the predominant observed structures are joints and flow banding. Measurements from flow banding plotted on stereonets using win-TENSOR software has provided an estimate for the general strike of the area lying 070° to 100° dipping at an average range angle of 70° to 85° while data from joints plotted on stereonets suggest multiple deformation events one of which conforms to the East Africa Rift System (striking WSW-ENE, NNE-SSW and N-S). 1. INTRODUCTION This paper focuses on performing a systematic geological mapping and description of structures and rocks of the Mnanka area. The Mnanka area is located in the Mara region, Tarime district within the Musoma Mara Greenstone Belt. The gold at Mnanka is host ed by volcanic rocks that belong to the Musoma Mara Greenstone Belt (Figure 1). The Mnanka volcanics are found within the Kemambo group that comprises of the sequence of predominant rhyolitic volcanic rocks, chert and metasediments south of the Nyarwana fault. -
Preliminary Volcano-Hazard Assessment for Augustine Volcano, Alaska
DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY Preliminary Volcano-Hazard Assessment for Augustine Volcano, Alaska by Christopher F. Waythomas and Richard B. Waitt Open-File Report 98-106 This report is preliminary and subject to revision as new data become available. Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Geological Survey Alaska Volcano Observatory Anchorage, Alaska 1998 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Thomas J. Casadevall, Acting Director For additional information: Copies of this report may be purchased from: U.S. Geological Survey U.S. Geological Survey Alaska Volcano Observatory Branch of Information Services 4200 University Drive Box 25286 Anchorage, AK 99508 Denver, CO 80225-0286 CONTENTS Summary of hazards at Augustine Volcano....................................... 1 Introduction ............................................................... 3 Purposeandscope ...................................................... 3 Physical setting of Augustine Volcano ...................................... 4 Relation to previous studies on Augustine hazards ............................. 5 Prehistoric eruptive history ................................................... 5 Historical eruptions ......................................................... 8 Hazardous phenomena at Augustine Volcano ..................................... 8 Volcanic hazards ....................................................... 12 Volcanicashclouds