DOCSLIB.ORG

Modelling Ice-Dammed Lake Drainage

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Modelling Ice-Dammed Lake Drainage Jonathan Kingslake Department of Geography University of Sheffield Modelling Ice-Dammed Lake Drainage PhD Thesis Submitted in accordance with the requirements for the degree of Doctor of Philosophy 9th January 2013 Abstract The drainage of ice-dammed lakes produces floods that can pose hazards, waste water resources and modulate ice flow. In this thesis I investigate several aspects of ice-dammed lake drainage through the development and analysis of mathematical models. After an introduction in the first chapter and a description of the mathematical background to the thesis in the second, the third chapter investigates the mechanisms behind observed variability in the size and timing of subglacial floods from ice-dammed lakes. In particular, I examine how environmental controls like the weather and the shape of glaciers affect floods. In the next chapter, I quantify how well simple models can predict the dates of floods from an ice-marginal lake in Kyrgyzstan. I find that incorporating environmental controls into models improves their prediction ability. Next I investigate the coupling between subglacial drainage and glacier motion during ice-dammed lake drainage by developing and analysing a model which couples a marginal lake, glacier sliding, subglacial drainage through a channel and subglacial drainage through a distributed system of cavities. I show how changes in lake level cause the rate at which a glacier slides to increase during the first half of floods and decrease during the second half. The next two chapters are concerned with two lake-drainage scenarios that involve water flowing as an open stream: firstly, the subglacial open- channel flow that occurs after a marginal lake drains completely during a flood, and secondly, the drainage of supraglacial lakes across the surface of ice sheets. I end the thesis with a summary of my findings and some suggestions of theoretical and field-based investigations that are worthwhile pursing in the future. Acknowledgements Thank you first to my supervisor Felix Ng for being so incredibly generous with his time and ideas. This thesis would not have been possible without his guidance and training. I am also grateful to my second supervisor Grant Bigg for comments on the thesis, to Andrew Sole for bringing his real-world experience of supraglacial lake drainage to bear on Chapter 7 and to Darrel Swift for many heated conversations about subglacial hydrology. Thank you to all the PhD students, post-docs and staff at Sheffield who have helped make my time in Sheffield so enjoyable. I also acknowledge the financial support of a University of Sheffield Postgraduate Studentship. Thank you to my parents Peter and Clare Kingslake for their constant support and to my Grandma Una Kingslake for assisting me financially throughout my time as a student. Lastly, thank you to my fiancée Jen for her fantastic support. The thesis would certainly not have been possible without it. Modelling Ice-dammed Lake Drainage Contents Chapter 1 Introduction .......................................................................... 1 Chapter 2 Mathematical background .................................................. 13 2.1 Introduction .................................................................................................................................. 13 2.2 Channels ........................................................................................................................................ 13 2.2.1 Steady-state drainage through an ice-walled channel ........................................................... 14 2.2.2 Time-dependent drainage through an ice-walled channel: Nye’s model .............................. 17 Channel geometry evolution ............................................................................................ 17 Mass conservation ............................................................................................................ 18 Momentum balance ......................................................................................................... 18 Energy balance .................................................................................................................. 18 Heat transfer ..................................................................................................................... 19 2.2.3 Fowler’s modification of Nye’s model .................................................................................... 21 2.2.4 The Nye-Fowler jökulhlaup model ......................................................................................... 24 Coupling the channel to a lake.......................................................................................... 24 Non-dimensionalisation .................................................................................................... 25 Boundary conditions ......................................................................................................... 27 Summary ........................................................................................................................... 28 2.2.5 Numerical methods ................................................................................................................ 29 Relaxation method ............................................................................................................ 29 Newton’s method ............................................................................................................. 32 Boundary layer method .................................................................................................... 37 Summary ........................................................................................................................... 39 2.3 Cavities .......................................................................................................................................... 40 2.3.1 Enhanced creep and regelation .............................................................................................. 40 2.3.2 Sliding with cavitation ............................................................................................................ 41 2.3.3 Linked-cavity drainage ............................................................................................................ 43 2.4 Summary and outlook ................................................................................................................... 44 Chapter 3 Environmental controls on flood cycles .............................. 47 3.1 Introduction .................................................................................................................................. 47 3.2 Flood cycles ................................................................................................................................... 49 3.2.1 Model setup ........................................................................................................................... 49 3.2.2 Control simulation: unstable growth in flood-cycle size ........................................................ 51 3.2.3 Stable flood cycles .................................................................................................................. 53 Negative basic hydraulic gradient near the lake suppresses flood cycle growth ............. 53 Supplying the channel with water along its length suppresses flood cycle growth ......... 56 Summary ........................................................................................................................... 59 3.3 Controls on the characteristics of flood cycles ............................................................................. 59 3.3.1 Sensitivity analysis of the reduced Nye-Fowler Model .......................................................... 60 3.3.2 Physics of the divide’s migration ............................................................................................ 63 3.4 Mode-locking, resonance and chaotic dynamics of the Nye-Fowler model ................................. 65 3.4.1 Model setup: time-varying model forcings ............................................................................ 66 3.4.2 Results .................................................................................................................................... 67 3.5 Discussion ...................................................................................................................................... 75 3.6 Conclusions ................................................................................................................................... 79 Chapter 4 Quantifying the predictability of the timing of jökulhlaups from Merzbacher Lake, Kyrgyzstan .......................................................... 81 I Modelling Ice-dammed Lake Drainage 4.1 Introduction ................................................................................................................................... 81 4.2 Flood-date prediction with the threshold model .......................................................................... 82 4.2.1 ‘Real’ and ‘Simple’ Schemes of weather forcing ..................................................................... 86 4.3 Study site and data sources ........................................................................................................... 87 4.3.1 The Inylchek Glaciers and Merzbacher Lake ..........................................................................
Load more

Recommended publications
  • Calving Processes and the Dynamics of Calving Glaciers ⁎ Douglas I
    Earth-Science Reviews 82 (2007) 143–179 www.elsevier.com/locate/earscirev Calving processes and the dynamics of calving glaciers ⁎ Douglas I. Benn a,b, , Charles R. Warren a, Ruth H. Mottram a a School of Geography and Geosciences, University of St Andrews, KY16 9AL, UK b The University Centre in Svalbard, PO Box 156, N-9171 Longyearbyen, Norway Received 26 October 2006; accepted 13 February 2007 Available online 27 February 2007 Abstract Calving of icebergs is an important component of mass loss from the polar ice sheets and glaciers in many parts of the world. Calving rates can increase dramatically in response to increases in velocity and/or retreat of the glacier margin, with important implications for sea level change. Despite their importance, calving and related dynamic processes are poorly represented in the current generation of ice sheet models. This is largely because understanding the ‘calving problem’ involves several other long-standing problems in glaciology, combined with the difficulties and dangers of field data collection. In this paper, we systematically review different aspects of the calving problem, and outline a new framework for representing calving processes in ice sheet models. We define a hierarchy of calving processes, to distinguish those that exert a fundamental control on the position of the ice margin from more localised processes responsible for individual calving events. The first-order control on calving is the strain rate arising from spatial variations in velocity (particularly sliding speed), which determines the location and depth of surface crevasses. Superimposed on this first-order process are second-order processes that can further erode the ice margin.
    [Show full text]
  • The Hyaloclastite Ridge Formed in the Subglacial 1996 Eruption in Gjfilp, Vatnaj6kull, Iceland: Present Day Shape and Future Preservation
    The hyaloclastite ridge formed in the subglacial 1996 eruption in Gjfilp, Vatnaj6kull, Iceland: present day shape and future preservation M. T. GUDMUNDSSON, F. PALSSON, H. BJORNSSON & ~. HOGNADOTTIR Science Institute, University of Iceland, Hofsvallag6tu 53, 107 Reykjavik, Iceland (e-mail: [email protected]) Abstract: In the Gjfilp eruption in 1996, a subglacial hyaloclastite ridge was formed over a volcanic fissure beneath the Vatnaj6kull ice cap in Iceland. The initial ice thickness along the 6 km-long fissure varied from 550 m to 750 m greatest in the northern part but least in the central part where a subaerial crater was active during the eruption. The shape of the subglacial ridge has been mapped, using direct observations of the top of the edifice in 1997, radio echo soundings and gravity surveying. The subglacial edifice is remarkably varied in shape and height. The southern part is low and narrow whereas the central part is the highest, rising 450 m above the pre-eruption bedrock. In the northern part the ridge is only 150-200m high but up to 2kin wide, suggesting that lateral spreading of the erupted material occurred during the latter stages of the eruption. The total volume of erupted material in Gj~tlp was about 0.8 km 3, mainly volcanic glass. The edifice has a volume of about 0.7 km 3 and a volume of 0.07 km 3 was transported with the meltwater from Gj~lp and accumulated in the Grimsv6tn caldera, where the subglacial lake acted as a trap for the sediments. This meltwater-transported material was removed from the southern part of the edifice during the eruption.
    [Show full text]
  • Ilulissat Icefjord
    World Heritage Scanned Nomination File Name: 1149.pdf UNESCO Region: EUROPE AND NORTH AMERICA __________________________________________________________________________________________________ SITE NAME: Ilulissat Icefjord DATE OF INSCRIPTION: 7th July 2004 STATE PARTY: DENMARK CRITERIA: N (i) (iii) DECISION OF THE WORLD HERITAGE COMMITTEE: Excerpt from the Report of the 28th Session of the World Heritage Committee Criterion (i): The Ilulissat Icefjord is an outstanding example of a stage in the Earth’s history: the last ice age of the Quaternary Period. The ice-stream is one of the fastest (19m per day) and most active in the world. Its annual calving of over 35 cu. km of ice accounts for 10% of the production of all Greenland calf ice, more than any other glacier outside Antarctica. The glacier has been the object of scientific attention for 250 years and, along with its relative ease of accessibility, has significantly added to the understanding of ice-cap glaciology, climate change and related geomorphic processes. Criterion (iii): The combination of a huge ice sheet and a fast moving glacial ice-stream calving into a fjord covered by icebergs is a phenomenon only seen in Greenland and Antarctica. Ilulissat offers both scientists and visitors easy access for close view of the calving glacier front as it cascades down from the ice sheet and into the ice-choked fjord. The wild and highly scenic combination of rock, ice and sea, along with the dramatic sounds produced by the moving ice, combine to present a memorable natural spectacle. BRIEF DESCRIPTIONS Located on the west coast of Greenland, 250-km north of the Arctic Circle, Greenland’s Ilulissat Icefjord (40,240-ha) is the sea mouth of Sermeq Kujalleq, one of the few glaciers through which the Greenland ice cap reaches the sea.
    [Show full text]
  • Ice Core Drilling and Subglacial Lake Studies on the Temperate Ice Caps in Iceland
    Ice core drilling and subglacial lake studies on the temperate ice caps in Iceland Iceland astride the Mid-Atlantic ridge Lecture # 36 Astrobiology Winter School Ice drilling projects in Iceland University of Hawaii, Jan. 2005 Thorsteinn Thorsteinsson ([email protected]) National Energy Authority Ice cover during the late glacial period. Combination of hot spot volcanism, spreading on the Mid-Atlantic ridge and glaciation leads to unusual geology. From Thordarson and Höskuldsson (2003). Subglacial volcanism beneath an ice sheet creates unusual landforms: Tuyas (tablemountains) and ridges. Herðubreið, N-Iceland Submarine eruptions create similar formations. Biologicial colonization monitored from the beginning Surtsey eruption, S. of Iceland, 1963-1967. Recent subglacial eruption in Grímsvötn, Vatnajökull ice cap. Jökulsárgljúfur canyons, N. Iceland: Formed in a catastrophic flood from Vatnajökull 2500 years ago. Icelandic analogs to hillside gullies on Mars Mars Mars Iceland Iceland Iceland Temperate ice caps Hofsjökull, 890 km2 cover >10% of Iceland Vatnajökull 2 Langjökull 8000 km 2 920 km Max. thickness: 950 m Mýrdalsjökull 550 km2 - Dynamic ice caps in a maritime climate. - High accumulation rates (2-4 m w.eq. yr-1) - Extensive melting during summer, except at highest elevations (> 1800 m) - Mass balance of ice caps negative since 1995 1972: A 415 m ice core was drilled on the NW-part of Vatnajökull Activities not continued at that time, drill was discarded. Mass balance of Hofsjökull Ice Cap 4 2 0 Winter balance -2 Summer balance H2O Net balance m -4 Cumulative mass balance -6 -8 -10 1987 1992 1997 2002 Climate, Water, Energy: A research project investigating the effect of climate change on energy production in the Nordic countries Temperature increase 1990-2050 °C CWE uses IPCC data to create scenarios for temperature and precipitation change in the Nordic region in the future Modelled change in volume of Hofsjökull ice cap 2000-2002, Modelled glacial meltwater using four different dT and dP discharge (run-off) 2000-2200.
    [Show full text]
  • Evidence for Extending Anomalous Miocene Volcanism at the Edge of The
    1 Evidence for Extending Anomalous Miocene Volcanism at the Edge of the 2 East Antarctic Craton 3 4 K. J. Licht1, T. Groth1, J. P. Townsend2, A. J. Hennessy1, S. R. Hemming3, T. P. Flood4, and M. 5 Studinger5 6 1Department of Earth Sciences, Indiana University-Purdue University Indianapolis, Indianapolis, IN, 7 USA, 2HEDP Theory Department, Sandia National Laboratories, Albuquerque, NM, USA, 3Department of 8 Earth and Environmental Sciences, Columbia University, Lamont-Doherty Earth Observatory, Palisades, 9 NY, USA, 4Geology Department, St. Norbert College, DePere, WI, USA, 5NASA Goddard Space Flight 10 Center, Greenbelt, MD, USA 11 12 Corresponding author: Kathy Licht ([email protected]) 13 14 Key Points: 15 x Olivine basalt, hyaloclastite erratics and detrital zircon at Earth’s southernmost moraine 16 (Mt. Howe) indicate magmatic activity 17- 25 Ma. 17 x The source, indicated by a magnetic anomaly (-740 nT) ~400 km inland from the West 18 Antarctic Rift margin, expands extent of Miocene lavas. 19 x Data corroborate lithospheric foundering beneath southern Transantarctic Mountains based 20 on location of volcanism (duration < 5 my). 21 22 Abstract 23 Using field observations followed by petrological, geochemical, geochronological, and 24 geophysical data we infer the presence of a previously unknown Miocene subglacial volcanic 25 center ~230 km from the South Pole. Evidence of volcanism is from boulders of olivine-bearing 26 amygdaloidal/vesicular basalt and hyaloclastite deposited in a moraine in the southern 27 Transantarctic Mountains. 40Ar/39Ar ages from five specimens plus U-Pb ages of detrital zircon 28 from glacial till indicate igneous activity 25-17 Ma.
    [Show full text]
  • 168 2Nd Issue 2015
    ISSN 0019–1043 Ice News Bulletin of the International Glaciological Society Number 168 2nd Issue 2015 Contents 2 From the Editor 25 Annals of Glaciology 56(70) 5 Recent work 25 Annals of Glaciology 57(71) 5 Chile 26 Annals of Glaciology 57(72) 5 National projects 27 Report from the New Zealand Branch 9 Northern Chile Annual Workshop, July 2015 11 Central Chile 29 Report from the Kathmandu Symposium, 13 Lake district (37–41° S) March 2015 14 Patagonia and Tierra del Fuego (41–56° S) 43 News 20 Antarctica International Glaciological Society seeks a 22 Abbreviations new Chief Editor and three new Associate 23 International Glaciological Society Chief Editors 23 Journal of Glaciology 45 Glaciological diary 25 Annals of Glaciology 56(69) 48 New members Cover picture: Khumbu Glacier, Nepal. Photograph by Morgan Gibson. EXCLUSION CLAUSE. While care is taken to provide accurate accounts and information in this Newsletter, neither the editor nor the International Glaciological Society undertakes any liability for omissions or errors. 1 From the Editor Dear IGS member It is now confirmed. The International Glacio­ be moving from using the EJ Press system to logical Society and Cambridge University a ScholarOne system (which is the one CUP Press (CUP) have joined in a partnership in uses). For a transition period, both online which CUP will take over the production and submission/review systems will run in parallel. publication of our two journals, the Journal Submissions will be two­tiered – of Glaciology and the Annals of Glaciology. ‘Papers’ and ‘Letters’. There will no longer This coincides with our journals becoming be a distinction made between ‘General’ fully Gold Open Access on 1 January 2016.
    [Show full text]
  • Dicionarioct.Pdf
    McGraw-Hill Dictionary of Earth Science Second Edition McGraw-Hill New York Chicago San Francisco Lisbon London Madrid Mexico City Milan New Delhi San Juan Seoul Singapore Sydney Toronto Copyright © 2003 by The McGraw-Hill Companies, Inc. All rights reserved. Manufactured in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be repro- duced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher. 0-07-141798-2 The material in this eBook also appears in the print version of this title: 0-07-141045-7 All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occurrence of a trademarked name, we use names in an editorial fashion only, and to the benefit of the trademark owner, with no intention of infringement of the trademark. Where such designations appear in this book, they have been printed with initial caps. McGraw-Hill eBooks are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs. For more information, please contact George Hoare, Special Sales, at [email protected] or (212) 904-4069. TERMS OF USE This is a copyrighted work and The McGraw-Hill Companies, Inc. (“McGraw- Hill”) and its licensors reserve all rights in and to the work. Use of this work is subject to these terms. Except as permitted under the Copyright Act of 1976 and the right to store and retrieve one copy of the work, you may not decom- pile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon, transmit, distribute, disseminate, sell, publish or sublicense the work or any part of it without McGraw-Hill’s prior consent.
    [Show full text]
  • EGU2015-13634-4, 2015 EGU General Assembly 2015 © Author(S) 2015
    Geophysical Research Abstracts Vol. 17, EGU2015-13634-4, 2015 EGU General Assembly 2015 © Author(s) 2015. CC Attribution 3.0 License. High-precision mapping of seismicity in the 2014 Bárdarbunga volcanic episode Kristín S. Vogfjörd, Martin Hensch, Gunnar B. Gudmundsson, and Kristín Jónsdóttir Icelandic Meteorological Office, Reykjavik, Iceland ([email protected]) The Bárdarbunga volcano and its associated fissure swarm in Iceland’s Eastern volcanic zone is a highly active system with over 20 eruptions in the last 11 centuries. The location of this active volcano and much of the fissure swarm under several hundred metres thick ice gives rise to multiple hazards, including explosive, subglacial eruptions and associated subglacial floods (jökulhlaups), as well as fissure eruptions extruding large volumes of lava. After a decade of increasing seismic activity, volcanic unrest at Bárdarbunga suddenly escalated into a minor subglacial eruption on 16 August 2014. In the following weeks seismic activity soared and surface defor- mation of tens of cm were observed, caused by rifting and a dyke intrusion, which propagated 48 km northward from the central volcano (Sigmundsson et al., 2014). The dyke propagation stopped just outside the glacial margin and ended in a fissure eruption at Holuhraun at the end of August. At the time of writing the eruption is ongoing, having extruded a lava volume of over 1 km3 and released high rates of SO2 into the atmosphere. Over twenty thousand microearthquakes have been recorded. Initially most were in the dyke, but after the first two weeks the activity around the caldera rim increased and over 70 shallow earthquakes with MW > 5 have been located along the caldera rim accompanied by caldera subsidence.
    [Show full text]
  • Future Iceberg Discharge from Columbia Glacier, Alaska
    W.T. Pfeffer Geophysical Consultants, LLC 4 December 2012 Report to Prince William Sound Citizen’s Regional Advisory Council: Future Iceberg Discharge from Columbia Glacier, Alaska Reference PWSRCAC Project #8551 Contractor: W. T. Pfeffer Geophysical Consultants, Nederland, Colorado Report #1 Part I: Data Report 1. Overview Columbia Glacier has the world’s longest and most detailed observational record of an ocean-terminating glacier in rapid retreat. The complexity and volume of data requires that its organization and archiving be managed with care. This report provides a compact overview of the available information, from raw data and imagery to maps, technical reports, and papers published in the scientific literature. The data is organized geographically, with observations of the sea floor and glacial bed followed by observations at the glacier surface and meteorological observations of the local atmosphere. Within each geographic section, observations are categorized by type or source (e.g. ship-borne sonar, aerial photography, ground- based time-lapse camera), and wherever possible, a citation or hyperlink to the data is provided. Finally, certain ancillary data, such as geodetic datum adjustments and photogrammetric control, are listed. A full discussion of the scientific literature on the Columbia Glacier is beyond the scope of this summary. However, a compact bibliography is included, and references are cited whenever necessary to explain the origin of a listed data quantity. History: Credit for the initiation of the Columbia Glacier data record goes to the U.S. Geological Survey (USGS), in particular the efforts of Mark Meier and Austin Post, who anticipated as early as the mid-1960s that Columbia Glacier was likely to begin a rapid retreat.
    [Show full text]
  • Subglacial to Emergent Volcanism at Shield Nunatak, Mt. Melbourne Volcanic Field, Antarctica
    Polarforschung 57 1/2: 27-41, 1987 Subglacial to Emergent Volcanism at Shield Nunatak, Mt. Melbourne Volcanic Field, Antarctica By G. Wörner and L. Viereck* Summary: Sections through Shield Nunatak vo1cano, an alkali basaltic subglacial table-mountain from the Mt. Melbourne Volcanic Field, are descrlbed. Resting on a base of older lava flows and a fossile tillite iayer, the volcano is formed mainly by massive ash and lapilli (mass flow) deposits while pillow lavas are absent. The recurrent stage of emergence from subglacial to subaerial conditions is characterized by de­ velopment of tuff rings from explosive interaction between magma and melt water, complex ash- and lapilli deposits, including lava flows brecciated by water-interaction and a subaerial basaltie ash-flow deposit. The sequence is capped by subaerial tuff rings, lava flows, scoria cones and reworked tephra. Available data on subaquatlc explosive voJcanism indicate that early Shield Nunatak basaltic lavas erupted un­ der less than 300 m of ice cover: later Iavas erupted under shallow-water and subaerial conditions. Shield Nunatak probably formed during a glacial period (possibly the last) when the ice thtckness in the Mt. Melbourne area must have been at least 200 m greater than at present. The volcano has suffered only minor glacial erosion and still almost has its original shape. Zusammenfassung: Es werden Profile beschrieben durch einen alkalibasaltischen subglazialen Vulkan (Shield Nunatak) im Mt. Melbourne Vulkanfeld. Die Unterlage des Vulkans wird von einer Serie subaerischer Lavaströme intermediärer Zusammensetzung (Mugearit) gebildet. Über einer Lage von Paleo-Till bilden massive Aschenablagerungen die Basis der subglazialen Sequenz. Kissenlaven fehlen.
    [Show full text]
  • Timeline Reconstruction of Holocene Jökulhlaups Along the Jökulsá Á
    Copyright by Greta Hoe Wells 2016 The Thesis Committee for Greta Hoe Wells Certifies that this is the approved version of the following thesis: Timeline Reconstruction of Holocene Jökulhlaups along the Jökulsá á Fjöllum Channel, Iceland APPROVED BY SUPERVISING COMMITTEE: Supervisor: Sheryl Luzzadder-Beach Timothy P. Beach Daene C. McKinney Timeline Reconstruction of Holocene Jökulhlaups along the Jökulsá á Fjöllum Channel, Iceland by Greta Hoe Wells, B.A. Thesis Presented to the Faculty of the Graduate School of The University of Texas at Austin in Partial Fulfillment of the Requirements for the Degree of Master of Arts The University of Texas at Austin May 2016 Abstract Timeline Reconstruction of Holocene Jökulhlaups along the Jökulsá á Fjöllum Channel, Iceland Greta Hoe Wells, M.A. The University of Texas at Austin, 2016 Supervisor: Sheryl Luzzadder-Beach The Jökulsá á Fjöllum is Iceland’s second longest river, draining from the Vatnajökull ice cap and winding for over 200 km through the eastern highlands before emptying into the Arctic Ocean. Hydrothermal activity and subglacial eruptions beneath Vatnajökull generate enormous quantities of meltwater, which can drain catastrophically in outburst floods, known as jökulhlaups. Jökulhlaups have flowed through the Jökulsá á Fjöllum channel throughout the Holocene, but intense debate exists over their timing and magnitude. While previous studies report a peak flood discharge of 0.9 x 106 m3 s-1, Howard et al. (2012) found evidence of a peak discharge of 2.2 x 107 m3 s-1, which would make this the largest known flood on Earth. This project seeks to test Howard et al.’s (2012) hypothesis and, more broadly, to reconstruct a timeline of Holocene jökulhlaups iv along the Jökulsá á Fjöllum.
    [Show full text]
  • The Mechanics of Subglacial Basaltic Lava Flow Emplacement: Inferring Paleo-Ice Conditions
    THE MECHANICS OF SUBGLACIAL BASALTIC LAVA FLOW EMPLACEMENT: INFERRING PALEO-ICE CONDITIONS by Jefferson D. G. Hungerford B. S. in Geology, University of Washington, 2002 Submitted to the Graduate Faculty of The Kenneth P. Dietrich School of Arts and Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Pittsburgh 2013 UNIVERSITY OF PITTSBURGH FACULTY OF THE KENNETH P. DIETRICH SCHOOL OF ARTS AND SCIENCES This dissertation was presented by Jefferson D. G. Hungerford It was defended on November 8, 2013 and approved by Dr. William Harbert, Professor, Department of Geology and Planetary Science Dr. Thomas A. Anderson, Professor Emeritus, Department of Geology and Planetary Science Dr. Daniel J. Bain, Assistant Professor, Department of Geology and Planetary Science Dr. Tracy K. P. Gregg, Associate Professor, Department of Geology, University at Buffalo Dissertation Advisor: Dr. Michael S. Ramsey, Professor, Department of Geology and Planetary Science ii Copyright © by Jefferson D. G. Hungerford 2013 iii THE MECHANICS OF SUBGLACIAL BASALTIC LAVA FLOW EMPLACEMENT: INFERRING PALEO-ICE CONDITIONS Jefferson D. G. Hungerford, PhD University of Pittsburgh, 2013 Recent studies of terrestrial glaciovolcanic terrains have elucidated the utility of volcanic deposits as recorders of ice conditions at the time of eruption. Practically all of these investigations, however, have focused upon the associations of volcaniclastic and coherent lava lithofacies at or proximal to the source vent. Very few studies have documented the emplacement of effusion-dominated, basaltic glaciovolcanic eruptions and their distal deposits that more accurately reveal paleo-ice conditions. Both Mauna Kea volcano, Hawaii and the Tennena volcanic center (TVC), on Mount Edziza, British Columbia, Canada, preserve records of interaction between coherent lavas and an ice sheet inferred to be associated with the last glacial maximum (LGM).
    [Show full text]