Physics
Scientific paper
Jul 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011e%26psl.307..191s&link_type=abstract
Earth and Planetary Science Letters, Volume 307, Issue 1, p. 191-200.
Physics
Volcanology, Mount St. Helens, Lava Dome, Rock Physics, Acoustic Emission, Volcano Seismology
Scientific paper
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.
Meredith Philip G.
Sammonds Peter R.
Smith Rosanna
Tuffen Hugh
No associations
LandOfFree
Evolution of the mechanics of the 2004-2008 Mt. St. Helens lava dome with time and temperature does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Evolution of the mechanics of the 2004-2008 Mt. St. Helens lava dome with time and temperature, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Evolution of the mechanics of the 2004-2008 Mt. St. Helens lava dome with time and temperature will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-990263