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Explosive to effusive transition during the largest volcanic eruption of the 20th century (Novarupta 1912, Alaska)

2014; Geological Society of America; Volume: 42; Issue: 8 Linguagem: Inglês

10.1130/g35593.1

1943-2682

C. T. Nguyen, Helge Torgersen, B. F. Houghton,

High-pressure geophysics and materials

Research Article| August 01, 2014 Explosive to effusive transition during the largest volcanic eruption of the 20th century (Novarupta 1912, Alaska) Chinh T. Nguyen; Chinh T. Nguyen * 1Department of Earth Science, Rice University, Houston, Texas 77005, USA *E-mail: ctn2@rice.edu. Search for other works by this author on: GSW Google Scholar Helge M. Gonnermann; Helge M. Gonnermann 1Department of Earth Science, Rice University, Houston, Texas 77005, USA Search for other works by this author on: GSW Google Scholar Bruce F. Houghton Bruce F. Houghton 2Department of Geology and Geophysics, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA Search for other works by this author on: GSW Google Scholar Geology (2014) 42 (8): 703–706. https://doi.org/10.1130/G35593.1 Article history received: 19 Feb 2014 rev-recd: 15 May 2014 accepted: 16 May 2014 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Chinh T. Nguyen, Helge M. Gonnermann, Bruce F. Houghton; Explosive to effusive transition during the largest volcanic eruption of the 20th century (Novarupta 1912, Alaska). Geology 2014;; 42 (8): 703–706. doi: https://doi.org/10.1130/G35593.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Silicic volcanic eruptions commonly show abrupt shifts between powerful and dangerous (Plinian) explosive episodes and gentle effusion of lava. Whether the onset of magma permeability and ensuing gas loss controls these transitions has been a subject of debate. We measured porosities and permeabilities in samples from the A.D. 1912 eruption of Novarupta volcano, Alaska, and analyzed them within the context of a well-constrained eruptive sequence that encompasses sustained explosive and effusive activity. For the explosive samples, we find that the degree of vesicle interconnectivity, measured as the ratio of connected to total porosity, decreases with phenocryst content and with increasing eruption intensity. Permeabilities of explosive samples show a weak dependence on porosity. Dome samples are not significantly different in permeability, but are of lower porosity, which together with abundant flattened vesicles is consistent with bubble collapse by permeable outgassing. Quantitative analysis indicates that outgassing alone was insufficient to affect the transition to effusive activity. Rather, the change from explosive to effusive activity was probably a consequence of high versus low magma ascent rates. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.