DOCSLIB.ORG

CHAMBERS. Páll Einarsson and Bryndís Brandsdóttir, Science

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
CHAMBERS. Páll Einarsson and Bryndís Brandsdóttir, Science Mars Polar Science 2000 4072.pdf THE KATLA SUBGLACIAL VOLCANO: EARTHQUAKES AND EVIDENCE FOR CRUSTAL MAGMA CHAMBERS. Páll Einarsson and Bryndís Brandsdóttir, Science Institute, University of Iceland, Hofsvallagata 53, 107 Reykjavík, Iceland ([email protected], [email protected]) Seismological methods can be used effectively to sidence cauldrons were formed in the ice within the study the internal structure and dynamics of volca- caldera on both occasions. noes. Hypocenters of earthquakes provide information The most dramatic evidence for prehistoric activity on the location of physical events, focal mechanism of Katla is a layer from about 12 000 ybp found in the studies give information on their nature. Seismic GRIP ice core, thought to correspond to Ash Zone 1 in waves that have propagated through the roots of vol- Atlantic sediment cores and a deposit formed by la- canoes carry information on the physical state of the hars, ash fall and surges on the south flank of the vol- material there, e. g. location of magma chambers. cano [9], [10]. Ash layers from Katla have also been Eruptive activity is usually accompanied by seismic identified in the GRIP core at 75 400 and 77 500 ice activity which can give invaluable information on core years [9]. processes in the crust s.a. magma migration. Several Katla and the surrounding volcanic area has of the Icelandic central volcanoes, including the sub- shown persistent high seismic activity for more than glacial Katla volcano in South Iceland, are the source four decades. No volcanic activity has been detected of persistent seismic activity in spite of little other during this time, however, with the exception of apparent signs of volcanic unrest [1], [2]. Several probable small subglacial eruptions in 1955 and 1999. physical processes can cause these earthquakes, s. a. Seismic data of the period 1978-1985 are anlysed slow inflation or deflation of a shallow-level magma here. Epicenters of this period fall into two distinct chamber, intrusion of magma into the shallow crust, clusters under the Mýrdalsjökull glacier. One cluster or thermal cracking due to heating or cooling of brittle is located within the caldera of the Katla volcano, the crustal material. other is centered in the Goðabunga area, west of the The Katla volcano is an off-rift volcano, covered caldera and beneath the western caldera rim. All by the glacier Mýrdalsjökull, and located in the vol- available data are consistent with hypocentral depths canic flank zone in South Iceland. It has produced of 0-4 km. Earthquakes of both clusters have distinct mainly transitional alkalic basalt lavas and tephra [3], characteristics of volcanic earthquakes, i. e. emergent [4], but more silicic rocks are known from nunataks in P-waves and poor S-waves. These characteristics are the glacier [5]. A caldera, 10 km x 13 km in diameter, more pronounced for the Goðabunga cluster. The co- mapped beneath the glacier by radio echo sounding incidence of the Katla cluster with the caldera and an (Björnsson et al., this conference), is underlain by a area of S-wave shadowing suggests that it is related to zone of low P-velocity and high S-wave attenuation an active magma chamber of the Katla volcano. interpreted as a magma chamber at a depth of less Similarly we take the Goðabunga cluster as an indi- than 3 km [6]. The Eldgjá fissure to the north is cator of the existance of a second magma chamber. It structurally connected to the Katla volcano, and the is a matter of definition whether this chamber repre- similarity of the chemistry of Katla and Eldgjá lavas sents a separate central volcano or a second magma has led to the suggestion that Eldgjá eruptions were chamber of the Katla volcano. The two clusters to- fed by lateral flow from the Katla magma chamber [7]. gether with the Eyjafjallajökull volcano to the west The Eyjafjallajökull volcano to the west of Katla has a and its fissure swarm form a pronounced E-W struc- distinct, E-W striking fissure swarm that merges with ture and appear to be mechanically coupled. Two his- the radial fissure system of Katla. The volcanoes thus torical eruptions of Eyjafjallajökull are temporally appear to be tectonically connected. related to Katla eruptions. Earthquakes under Katla eruptions during the last 1100 years are Goðabunga show a clear seasonal correlation. Earth- relatively well known from historical records [8]. At quakes are several times more likely to happen in the least 17 eruptions occurred in this time, the latest latter half of the year than in the first [11]. Two fac- large ones in 1823, 1860 and 1918. These eruptions tors are likely to be effective here, the load of the gla- were accompanied by substantial jökulhlaups from the cier ice and the pore pressure in the crust beneath the glacier. Small subglacial eruptions appear to have glacier. Both factors would tend to reduce the friction occurred in 1955 and 1999 as suggested by seismicity, on fault planes in the autumn when melt water seeps both earthquakes and volcanic tremor recorded prior into the crust and increases the pore pressure. We ar- to small jökulhlaups. No eruption was visible but sub- gue that the pore pressure produces a larger effect than the change in the ice load. Mars Polar Science 2000 4072.pdf KATLA SEISMICITY: P. Einarsson and B. Brandsdóttir References: [1] Tryggvason, E. (1973) Bull. Seismol. Soc. Am., 63, 1327-1348. [2] Einarsson, P. (1991) Tectonophys., 189, 261-279. [3] Jakobsson, S. P. (1979) Acta Nat. Isl., 26, 103 pp. [4] Steinþórsson, S. et al. (1985) JGR, 90, 10,027-10,042. [5] Jóhannes- son, H. et al. (1982) Museum of Nat. Hist. and Iceland Geod. Surv. [6] Guðmundsson, Ó. et al. (1994) Geo- phys. J. Int., 119, 277-296. [7] Sigurdsson, H., and S. Sparks (1978) Nature, 274, 126-130. [8] Þórarinsson, S. (1975) Ferðafélag Íslands, Árbók, 125-149. [9] Grönvold, K. et al. (1995) Earth Planet. Sci. Lett., 135, 149-155. [10] Lacasse, C. et al. (1995) Bull. Volcanol., 57, 18-32. [11] Brandsdóttir, B., and Ei- narsson, P. (1992) In: Volcanic Seismology (eds. P. Gasparini and K. Aki), Springer Verlag, 212-222..
Load more

Recommended publications
  • PDF Available Here
    Edinburgh Research Explorer Vegetational response to tephra deposition and land-use change in Iceland: a modern analogue and multiple working hypothesis approach to tephropalynology Citation for published version: Edwards, KJ, Dugmore, AJ & Blackford, JJ 2004, 'Vegetational response to tephra deposition and land-use change in Iceland: a modern analogue and multiple working hypothesis approach to tephropalynology', Polar Record, vol. 40, no. 213, pp. 113-120. https://doi.org/10.1017/S0032247403003000 Digital Object Identifier (DOI): 10.1017/S0032247403003000 Link: Link to publication record in Edinburgh Research Explorer Document Version: Publisher's PDF, also known as Version of record Published In: Polar Record Publisher Rights Statement: Published in Polar Record by Cambridge University Press (2004) General rights Copyright for the publications made accessible via the Edinburgh Research Explorer is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. Take down policy The University of Edinburgh has made every reasonable effort to ensure that Edinburgh Research Explorer content complies with UK legislation. If you believe that the public display of this file breaches copyright please contact [email protected] providing details, and we will remove access to the work immediately and investigate your claim. Download date: 02. Oct. 2021 Polar Record 40 (213): 113–120 (2004). Printed in the United Kingdom. DOI: 10.1017/S0032247403003000 113 Vegetational response to tephra deposition and land-use change in Iceland: a modern analogue and multiple working hypothesis approach to tephropalynology Kevin J.
    [Show full text]
  • Monitoring Volcanoes in Iceland and Their Current Status
    Monitoring volcanoes in Iceland and their current status Sara Barsotti Coordinator for Volcanic Hazards, [email protected] Overview • Volcanoes and volcanic eruption styles in Iceland • Monitoring volcanoes and volcanic eruptions • Current status at • Hekla • Katla • Bárðarbunga • Grímsvötn • Öræfajökull 2 The catalogue of Icelandic Volcanoes – icelandicvolcanoes.is It includes historical activity, current seismicity, possible hazards and scenarios, GIS-based map layers to visualize eruption product extensions (lava flows, ash deposits) – ICAO project 3 Explosive vs. Effusive eruption Eyjafjallajökull 2010 Bárðarbunga - Holuhraun 2014-2015 • Volcanic cloud (possibly up to • Lava flow the stratosphere) • Volcanic gas into the • Tephra fallout atmosphere (hardly higher • Lightning than the tropopause) • Floods (if from ice-capped volcano) • Pyroclastic flows 4 Volcanic ash hazards from Icelandic volcanoes All these volcanoes have volcanic ash as one of the principal hazards 5 Eruption in Iceland since 1913 Year Volcano VEI Note Stile of activity 2014 Holuhraun (Bárðarbunga) 1 Effusive 2011 Grímsvötn 4 Ice Explosive 2010 Eyjafjallajökull 3 Ice Explosive/effusive 2004 Grímsvötn 3 Ice Explosive 2000 Hekla 3 Effusive/explosive 1998 Grímsvötn 3 Ice Explosive 1996 Gjálp (Grímsvötn) 3 Ice Subglacial-explosive 1991 Hekla 3 Effusive/explosive 1983 Grímsvötn 2 Ice Explosive 1980-81 Hekla 3 Effusive/explosive 1975-84 Krafla fires (9 eruptions) 1 Effusive 1973 Heimaey 2 Effusive/explosive 1970 Hekla 3 Effusive/explosive Instrumental monitoring 1963-67
    [Show full text]
  • The Eyjafjallajokull Eruption of March-May 2010
    The Eyjafjallajokull eruption of March-May 2010 Kathryn Goodenough, British Geological Survey, West Mains Road, Edinburgh EH9 3LA Abstract The March-May 2010 volcanic eruption in southern Iceland brought volcanoes to the attention of the general public, as north-westerly winds carried a cloud of volcanic ash across Europe and caused major disruption to air travel. This article describes that eruption, looks at the historical background, and asks what whether we can expect to see more such disruption in the future. Introduction On the 20th of March 2010, a volcanic eruption began in the area of Fimmvörðuháls in southern Iceland, with lava erupting from fissures in spectacular ‘fire fountains’. By Icelandic standards, this was not particularly unusual; in fact, it was considered a welcome tourist attraction, attracting thousands of visitors a day, as described by the Iceland Review Online (www.icelandreview.com). Then, on the 14th of April, the site of the eruption abruptly moved from its first, ice-free location, to the ice-capped central crater of nearby Eyjafjallajökull volcano. Here, when the magma rising up beneath the volcano reached the surface, it melted the ice in the crater. The interaction of the hot magma with ice-cold water caused a reaction rather like that between hot oil and water; it exploded, throwing a column of volcanic ash and steam almost ten kilometres into the air. At the time, the prevailing winds were north-westerly, and so they carried the ash south-eastwards over Europe, where it caused widespread disruption to flights for several weeks, and stranded thousands of people away from home.
    [Show full text]
  • Total Grain Size Distribution in Selected Icelandic Eruptions
    Total Grain Size Distributi on in Selected Icelandic Erupti ons Work for the Internati onal Civil Aviati on Organizati on (ICAO) and the Icelandic Meteorological Offi ce Authors: Ármann Höskuldsson, Maria Janebo, Thorvaldur Thordarson, Thóra Björg Andrésdó� r, Ingibjörg Jónsdó� r, Jónas Guðnason, Johanne Schmith, William Moreland, Agnes Ösp Magnúsdó� r University of Iceland Total Grain-Size Distribution in Selected Icelandic Eruptions Total Grain-Size Distribution in Selected Icelandic Eruptions Copyright © 2018 Á. Höskuldsson, M.H. Janebo, T. Thordarson, T. B. Andrésdóttir, I. Jónsdóttir J. Guðnason, J. Schmith, W. Moreland, A. Ö. Magnúsdóttir All rights reserved Institute of Earth Sciences University of Iceland Sturlugata 7 101 Reykjavík ISBN 978-9935-9300-4-0 Table of contents Abstract 7 1 Introduction 8 2 Explosive volcanism in Iceland 8 3 Selected volcanoes 9 4 Total Grain-Size Distribution (TGSD) 10 5 The work strategy 11 6 Summary of the project 12 7 Eruption summaries and TGSDs 12 7.1 Hekla 13 Hekla 1104 15 Hekla 1300 16 Hekla 1693 17 Hekla 1766 18 Hekla 1845 19 Hekla 1991 20 Hekla 2000 21 7.2 Katla 22 Katla 1625 23 Katla 1755 24 Katla 934 - Eldgjá 25 7.3 Askja 27 Askja 1875 28 7.4 Grímsvötn 30 Grímsvötn 2004 31 Grímsvötn 2011 32 7.67.5 ReykjanesEyjafjallajökull 3533 ReykjanesEyjafjallajökull 1226 2010 3634 8 Conclusions 37 9 Future work 38 References 42 ListFigure of 1. figures Distribution of volcanic systems in Iceland. 9 Figure 2. Location of Hekla 13 Figure 3. Hekla volcano 13 Figure 4. Main area affected by tephra fall from the Hekla 1104 eruption 15 Figure 5.
    [Show full text]
  • Talking Points Volcanoes and Volcanic Ash Part 1
    Talking Points Volcanoes and Volcanic Ash Part 1 Slide 1 - Title Page and intro to authors. Jeff Braun – Research Associate Cooperative Institute for Research in the Atmosphere (CIRA) Jeff Osiensky - Deputy Chief, Environmental & Scientific Services Division (ESSD), NWS Alaska Region Bernie Connell – CIRA/SHyMet – SHyMet Program Leader Kristine Nelson – NWS Alaska Region (AR) – MIC Anchorage Center Weather Service Unit (CWSU) Tony Hall – NWS AR – MIC Alaskan Aviation Weather Unit Slide 2 (6) – WHY? Slide 2, Page 2 - Volcanic Ash and Aviation Safety: Proceedings of the First International Symposium on Volcanic Ash and Aviation Safety – 1991 - Introductory Remarks by Donald D. Engen (Vice Admiral) Donald D. Engen – a legend in aviation, aviation education, and aviation history. U.S. Navy from 1942 (as a Seaman Second Class) - retiring in 1978 as a Vice Admiral. Also, – General Manager of the Piper Aircraft Corporation – a member of the National Transportation Board; appointed Administrator of the Federal Aviation Administration by President Ronald Reagan, and was also appointed Director of the Smithsonian Air and Space Museum, where he served until his death (1999 – glider accident). Slide 2, Page 3 – What to call this volcano? Eyjafjallajökull - phonetically “Eye a Fyat la yu goot” However, this volcano is also known as “Eyjafjöll” which is pronounced “Eva logue” And finally, this volcano is, thankfully, also known as “E15.” (or the basic “Iceland Volcano”). Some statistics concerning Eyjafjallajökull volcano. The volcano in Iceland erupts explosively April 14 after a two day hiatus (originally beginning rather benignly March 20, 2010). Point 1: That translates to nearly $200 million loss per day Point 2: That represents 10 percent of the entire global air traffic system! Point 3: (65,000 in the ten day period mentioned above) throughout Europe Point 5: In locations far from the erupting volcano, (ie the United States, India, and southeast Asia), travel was significantly affected.
    [Show full text]
  • Educational Tour – Katla Geopark
    Educational tour – Katla Geopark Katla Geopark is Iceland´s first geopark and it opens up a natural wonderland to the visitor. A top priority of the park is to protect the natural environment, promote local sustainable development, introduce local culture and place a strong emphasis on nature tourism. Katla geopark is located in the southern part of the country and covers 9542 km2 or around 9,3 % of the total area of Iceland with population around 2700. The Geopark got its name from one of its most known volcanoes, Katla which is under the glacier Mýrdalsjökull. Katla Geopark is in every sense the land of ice and fire, with its towering glaciers and active volcanoes. These forces have been shaping the land for thousands of years and the nearest examples of that are the powerful eruptions in Eyjafjallajökull 2010 and Grímsvötn 2011. But there is also more amazing landscapes in the area, mountains, lakes, black sandy beaches, green pastures and meadows, powerful glacial rivers, beautiful waterfalls and vast lava fields. Katla Geopark´s Educational tours are tailor-made for school groups at highschool and university levels of education. Our Educational tours include all you need for an enjoyable schooltrip; a guide, a bus, warm and welcoming places to sleep and our best quality local food. DAY 1 Thorsmörk Nature Reserve – The Land of the Thundergod Thor Topic: Icelandic Sagas, settlement, protected sites, team building, experience the wilderness, improving confidence Once you have landed in Keflavik Airport a bus and a local guide from Katla Geopark will be waiting for you to welcome your to Iceland.
    [Show full text]
  • Long-Period Events with Strikingly Regular Temporal Patterns on Katla Volcano’S South Flank (Iceland)
    Long-period events with strikingly regular temporal patterns on Katla volcano’s south flank (Iceland) Giulia Sgattoni1,2,3*, Zeinab Jeddi3,4, Ólafur Guðmundsson3, Páll Einarsson2, Ari Tryggvason3, Björn Lund3, Federico Lucchi1 1 Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna, Italy 2 Institute of Earth Sciences, Science Institute, University of Iceland, Reykjavik, Iceland 3 Department of Earth Sciences, Uppsala University, Uppsala, Sweden 4 CNDS, Centre for Natural Disaster Science, Uppsala University, Uppsala, Sweden *Corresponding author: [email protected] Abstract Katla is a threatening volcano in Iceland, partly covered by the Mýrdalsjökull ice cap. The volcano has a large caldera with several active geothermal areas. A peculiar cluster of long-period seismic events started on Katla’s south flank in July 2011, during an unrest episode in the caldera that culminated in a glacier outburst. The seismic events were tightly clustered at shallow depth in the Gvendarfell area, 4 km south of the caldera, under a small glacier stream on the southern margin of Mýrdalsjökull. No seismic events were known to have occurred in this area before. The most striking feature of this seismic cluster is its temporal pattern, characterized by regular intervals between repeating seismic events, modulated by a seasonal variation. Remarkable is also the stability of both the time and waveform features over a long time period, around 3.5 years. No comparable examples have been found in the literature. Both volcanic and glacial processes can produce similar waveforms and therefore have to be considered as potential seismic sources. Discerning between these two causes is critical for monitoring glacier-clad volcanoes and has been controversial at Katla.
    [Show full text]
  • The 2011 Unrest at Katla Volcano: Characterization and Interpretation of the Tremor Sources
    The 2011 unrest at Katla volcano: characterization and interpretation of the tremor sources Giulia Sgattoni1,2,3*, Ólafur Gudmundsson3, Páll Einarsson2, Federico Lucchi1, Ka Lok Li3, Hamzeh Sadeghisorkhani3, Roland Roberts3, Ari Tryggvason3 1 Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna, Italy 2 Institute of Earth Sciences, Science Institute, University of Iceland, Reykjavik, Iceland 3 Department of Earth Sciences, Uppsala University, Uppsala, Sweden *Corresponding author: [email protected] Abstract A 23 hour tremor burst was recorded on July 8-9th 2011 at the Katla subglacial volcano, one of the most active and hazardous volcanoes in Iceland. This was associated with deepening of cauldrons on the ice cap and a glacial flood that caused damage to infrastructure. Increased earthquake activity within the caldera started a few days before and lasted for months afterwards and new seismic activity started on the south flank. No visible eruption broke the ice and the question arose as to whether this episode relates to a minor subglacial eruption with the tremor being generated by volcanic processes, or by the flood. The tremor signal consisted of bursts with varying amplitude and duration. We have identified and described three different tremor phases, based on amplitude and frequency features. A tremor phase associated with the flood was recorded only at stations closest to the river that flooded, correlating in time with rising water level observed at gauging stations. Using back-projection of double cross-correlations, two other phases have been located near the active ice cauldrons and are interpreted to be caused by volcanic or hydrothermal processes.
    [Show full text]
  • GIS Final Project: Glacial Meltwater Flow Paths Around Katla Volcano, Iceland
    Sarah Doyle May 6th, 2010 GEO 326G/387G GIS Final Project: Glacial Meltwater Flow Paths around Katla Volcano, Iceland Introduction Iceland is an island nation on top of the Mid-Atlantic Ridge just below the Arctic Circle. Formed by volcanic activity, it contains many active volcanoes, many of which have caused regional and global havoc. The 1785 eruption of the Laki volcano produced enough volcanic ash to cause worldwide famine, and the April, 2010 eruption of the Eyjafjallajokull volcano created an ash cloud that upset air travel across Europe. In addition to volcanic activity, Iceland is known for its vast glaciers. The largest glacier in Europe is located here and it covers an area of 8,160 km2 and in some places is more than 1000 m thick (http://notendur.hi.is/oi/icelandic_glaciers.htm). The combination of glaciers overlying active volcanoes makes “jokulhlaups”, or bursts of glacial meltwater that create fast moving floods of high volumes of water, a major natural hazard. The Katla volcano underlies the Myrdalsjokull glacier (Area in 2000 of 590 m2) in southern Iceland. On the occurrence of a volcanic eruption (roughly every 40-80 yrs since 930 AD) this glacier has produced jokulhlaups of large volumes. A 1755 eruption was estimated to have a peak discharge of 200,000-400,000 m3/s (en.wikipedia.org/wiki/Myrdalsjokull). Iceland is a relatively low-lying, flat island, besides the high topography created by volcanoes. Therefore, floods can travel long distances, and around the bases of calderas, can have great velocities. The Katla volcano is due to erupt again soon, and was feared to do so around the same time as the nearby Eyjafjallajokull volcano which erupted this April.
    [Show full text]
  • Survival of the Mýrdalsjökull Ice Cap Through The
    Survival of the Mýrdalsjökull ice cap through the Holocene thermal maximum: evidence from sulphur contents in Katla tephra layers (Iceland) from the last ∼8400 years Bergrun Oladottir, T. Thordarson, Olgeir Sigmarsson To cite this version: Bergrun Oladottir, T. Thordarson, Olgeir Sigmarsson. Survival of the Mýrdalsjökull ice cap through the Holocene thermal maximum: evidence from sulphur contents in Katla tephra layers (Iceland) from the last ∼8400 years. Annals of Glaciology, International Glaciological Society, 2007, 45 (1), pp.183-188. 10.3189/172756407782282516. hal-00338717 HAL Id: hal-00338717 https://hal.archives-ouvertes.fr/hal-00338717 Submitted on 10 May 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Distributed under a Creative Commons Attribution| 4.0 International License Annals of Glaciology 45 2007 183 Survival of the My´rdalsjo¨kull ice cap through the Holocene thermal maximum: evidence from sulphur contents in Katla tephra layers (Iceland) from the last 8400 years Bergrun A. OLADOTTIR,1 Thor THORDARSON,2,3 Gudrun LARSEN,3 Olgeir SIGMARSSON1,3 1Universite´ Blaise Pascal, OPGC and CNRS, 5 rue Kessler, 63038 Clemont-Ferrand, France E-mail: [email protected] 2University of Edinburgh, School of Geoscience, The King’s Buildings, West Mains Road, Edinburgh EH9 3JW, UK 3Institute of Earth Sciences, University of Iceland, 101 Reykjavı´k, Iceland ABSTRACT.
    [Show full text]
  • Chapter III. Öræfajökull Volcano: Eruption Melting Scenarios
    III. ÖRÆFAJÖKULL VOLCANO: ERUPTION MELTING SCENARIOS Magnús T. Gudmundsson *, Þórdís Högnadóttir *, Eyjólfur Magnússon * * Nordic Volcanological Centre, Institute of Earth Sciences, University of Iceland 1. Introduction associated with volcanic activity in Öræfajökull. The approach is therefore to Observations of recent volcanic unrest consider what can be defined as realistic demonstrate that melting of ice in eruptions worst case scenarios. This needs to be kept in within glaciers can be extremely fast. The mind when considering the results. The best documented cases have occurred in the scenarios with the highest probability are less last quarter of a century in Grímsvötn, Gjálp, extreme. Three types of eruptions/events are Eyjafjallajökull and Redoubt in Alaska (e.g. considered. (1) Eruptions within the caldera Gudmundsson et al., 1997, 2004; Gud- of Öræfajökull (thick ice), (2) eruptions on mundsson, 2005; Magnússon et al., 2012a; the flanks (thin ice), and (3) pyroclastic Waythomas et al., 2013) and some earlier density currents (PDCs). The values of events such as the Katla 1918 eruption various parameters used in calculations and (Tómasson, 1996; Björnsson, 2003) and the definitions of terms are listed in Table III-1. eruptions of Mount St. Helens in 1980–1983 In this chapter a short overview of the area (Pierson, 1999), Nevado del Ruiz in 1985 being considered is given in Section 2 while (Pierson et al., 1990) and Redoubt in 1989– the magnitudes of eruptions that occur in 90 (Dorava and Meyer, 1994; Trabant et al., Iceland are reviewed briefly in Section 3. In 1994). For eruptions observed in Iceland, the Section 4, calorimetric considerations on the highest rates of heat transfer and melting various types of volcanic events are presented occur in the early, fully subglacial phases of and empirical data used to constrain explosive eruptions where the magma is efficiencies of processes.
    [Show full text]
  • Understanding Visitor Perspectives on Volcano Tourism at Mount Pinatubo, Philippines: a Mixed Methods Study
    Understanding Visitor Perspectives on Volcano Tourism at Mount Pinatubo, Philippines: A Mixed Methods Study Richard Aquino A thesis submitted to Auckland University of Technology in partial fulfilment of the requirements for the degree of Master of International Tourism Management (MITM) 2015 Faculty of Culture and Society School of Hospitality and Tourism Primary Supervisor: Dr Heike Schänzel Secondary Supervisor: Assoc Prof Kenneth F Hyde TABLE OF CONTENTS LIST OF APPENDICES ............................................................................................... v LIST OF FIGURES ..................................................................................................... vi LIST OF TABLES ...................................................................................................... vii LIST OF ABBREVIATIONS ...................................................................................... ix ATTESTATION OF AUTHORSHIP ............................................................................ x ACKNOWLEDGEMENTS ......................................................................................... xi ABSTRACT...................................................................................................................xiii Chapter 1 INTRODUCTION ................................................................................... 1 1.1 Background to the study ................................................................................. 1 1.2 Volcano tourism in the Philippines.................................................................
    [Show full text]