Computational approaches to tephra geochemical correlation and deposit volume estimation

• Author / Creator

  Bolton, Matthew

• This thesis presents two studies employing computational approaches to tephra source attribution and tephra volume estimation.
  Glass major oxide data was used to train 11 classification algorithms. Each classifier probabilistically attributed tephra chemistries to one of ten volcanic sources from Alaska. An ensemble model, combining random forest and artificial neural network predictions, was highly accurate on held-out and new data from Eklutna Lake, Alaska. Results matched visual assessment and identified tephra geochemically consistent with the Pleistocene Emmons Lake Volcanic Center (Dawson tephra) in Holocene-aged sediments.
  The May 18, 1980 Mount St. Helens eruption’s volume was reassessed. Spline interpolation permitted thickness, area, and cumulative volume to be calculated from a new synthesized thickness map at high resolution. A novel approach and cumulative volume plots show tephra volume for the deposit with clarity and uncertainty estimation. Reassessment indicates comparable volume to past estimates, but distal volume is proportionally larger than previously thought.

• Subjects / Keywords

  • Tephra
  • Volcano
  • Ash
  • Volume
  • Geochemistry

• Graduation date

  Spring 2021

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-0v1x-2111

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.