UCL  IRIS
Institutional Research Information Service
UCL Logo
Please report any queries concerning the funding data shown on the profile page to:

http://www.ucl.ac.uk/finance/secure/research/post_award
Please report any queries concerning the student data shown on the profile page to:

Email: portico-services@ucl.ac.uk

Help Desk: http://www.ucl.ac.uk/ras/portico/helpdesk
Publication Detail
Evolution of the mechanics of the 2004-2008 Mt. St. Helens lava dome with time and temperature
  • Publication Type:
    Journal article
  • Publication Sub Type:
    Article
  • Authors:
    Smith R, Sammonds PR, Tuffen H, Meredith PG
  • Publisher:
    ELSEVIER SCIENCE BV
  • Publication date:
    01/07/2011
  • Pagination:
    191, 200
  • Journal:
    EARTH PLANET SC LETT
  • Volume:
    307
  • Issue:
    1-2
  • Print ISSN:
    0012-821X
  • Language:
    EN
  • Keywords:
    volcanology, Mount St. Helens, lava dome, rock physics, acoustic emission, volcano seismology, EXPERIMENTAL INSIGHTS, POROUS SANDSTONES, SILICIC MAGMA, FRACTURE, SEISMICITY, TRANSITION, EARTHQUAKES, ERUPTIONS, VOLCANO, FLOW
  • Addresses:
    Smith, R
    Univ Munich
    Dept Earth & Environm Sci
    D-80333
    Munich
    Germany
Abstract
The 2004-2008 eruption of Mount St. Helens, Washington, USA, formed a typical example of a Pelean spiny lava dome, with solid spines of crystalline silicic lava extruded along shear zones bounded by fault gouge (Cashman et al., 2008; Iverson et al., 2006). Creation of and movement along shear zones in this erupting lava, recorded as shallow micro-earthquakes, were thus key controls on eruption style and rate, in addition to dome stability. As eruption style and lava dome stability often change within individual eruptions, it is important to identify how the strength of dome rocks changes with temperature, time, texture and extrusion rate. However, critical values of the shear strength of dome lava at eruptive temperatures have never been measured. We have found in controlled laboratory experiments simulating eruption conditions that dome lava strength increased during the course of the 2004-2008 eruption of Mount St. Helens, as the textures became more crystalline and less porous. Increasing lava strength during the eruption would lead to deformation becoming increasingly localised to shear zones, explaining why the extrusion style and centre were so consistent. Acoustic emissions and microstructure analysis indicate that fracturing was more localised at higher temperatures, resulting in higher strengths at eruptive temperature compared to ambient temperatures for later erupted samples. The strength of these later erupted samples at eruptive temperatures increased markedly with strain rate. This would damp any increases in effusion rate that may result from changes in magma pressure, explaining the steady effusion rate at Mount St. Helens from 2004 to 2008. (c) 2011 Elsevier B.V. All rights reserved.
Publication data is maintained in RPS. Visit https://rps.ucl.ac.uk
 More search options
UCL Authors
Dept of Earth Sciences
Dept of Earth Sciences
University College London - Gower Street - London - WC1E 6BT Tel:+44 (0)20 7679 2000

© UCL 1999–2011

Search by