Focusing of melt near the top of the Mount St. Helens (USA) magma reservoir and its relationship to major volcanic eruptions (2018)

Research Article| August 01, 2018 Focusing of melt near the top of the Mount St. Helens (USA) magma reservoir and its relationship to major volcanic eruptions Eric Kiser; Eric Kiser * 1University of Arizona, Department of Geosciences, Tucson, Arizona 85721, USA *E-mail: ekiser@email.arizona.edu Search for other works by this author on: GSW Google Scholar Alan Levander; Alan Levander 2Rice University, Department of Earth, Environmental and Planetary Sciences, Houston, Texas 77005, USA Search for other works by this author on: GSW Google Scholar Colin Zelt; Colin Zelt 2Rice University, Department of Earth, Environmental and Planetary Sciences, Houston, Texas 77005, USA Search for other works by this author on: GSW Google Scholar Brandon Schmandt; Brandon Schmandt 3University of New Mexico, Department of Earth and Planetary Sciences, Albuquerque, New Mexico 87131, USA Search for other works by this author on: GSW Google Scholar Steven Hansen Steven Hansen 4Macquarie University, Department of Earth and Planetary Sciences, NSW 2109, Australia Search for other works by this author on: GSW Google Scholar Geology (2018) 46 (9): 775–778. https://doi.org/10.1130/G45140.1 Article history received: 10 May 2018 rev-recd: 10 Jul 2018 accepted: 17 Jul 2018 first online: 01 Aug 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation Eric Kiser, Alan Levander, Colin Zelt, Brandon Schmandt, Steven Hansen; Focusing of melt near the top of the Mount St. Helens (USA) magma reservoir and its relationship to major volcanic eruptions. Geology 2018;; 46 (9): 775–778. doi: https://doi.org/10.1130/G45140.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyGeology Search Advanced Search Abstract The volumes, melt fractions, and geometries of shallow magma reservoirs strongly influence the hazards associated with volcanic regions. This study investigates these properties of the shallow Mount St. Helens (Washington State, USA) magma reservoir using modeled P-wave velocities (Vp) from data collected during the Imaging Magma Under St. Helens (iMUSH) active-source seismic experiment. This model shows a low Vp anomaly between 3.5 and 14 km depth that is inferred to represent the magma reservoir that feeds this volcano. The shape of this feature is complex compared to previous models of the magma reservoir and at most depths has a central location that is offset to the south/southwest from the volcanic edifice. Using a calculated relationship between Vp and melt fraction, it is estimated that anomalously high melt fractions of 10–12% occur between 4 and 6 km depth within the inferred magma reservoir. A majority of the magma source depths of major eruptions at Mount St. Helens over the past 4 k.y. fall within this same depth range. This relationship suggests persistent properties of the magma reservoir that focus magma accumulation within this depth range over multiple eruptive episodes. Future monitoring of changes in the seismic properties in this shallow portion of the reservoir may improve forecasting for major volcanic eruptions at Mount St. Helens. You do not currently have access to this article.