Emplacement and inflation of pahoehoe sheet flows: Observations and measurements of active lava flows on Kilauea Volcano, Hawaii

Abstract

Research Article| March 01, 1994 Emplacement and inflation of pahoehoe sheet flows: Observations and measurements of active lava flows on Kilauea Volcano, Hawaii KEN HON; KEN HON 1U. S. Geological Survey, Hawaiian Volcano Observatory, Hawaii National Park, Hawaii 96718 Search for other works by this author on: GSW Google Scholar JIM KAUAHIKAUA; JIM KAUAHIKAUA 1U. S. Geological Survey, Hawaiian Volcano Observatory, Hawaii National Park, Hawaii 96718 Search for other works by this author on: GSW Google Scholar ROGER DENLINGER; ROGER DENLINGER 1U. S. Geological Survey, Hawaiian Volcano Observatory, Hawaii National Park, Hawaii 96718 Search for other works by this author on: GSW Google Scholar KEVIN MACKAY KEVIN MACKAY 2Victoria University of Wellington, Wellington, New Zealand Search for other works by this author on: GSW Google Scholar GSA Bulletin (1994) 106 (3): 351–370. https://doi.org/10.1130/0016-7606(1994)106<0351:EAIOPS>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation KEN HON, JIM KAUAHIKAUA, ROGER DENLINGER, KEVIN MACKAY; Emplacement and inflation of pahoehoe sheet flows: Observations and measurements of active lava flows on Kilauea Volcano, Hawaii. GSA Bulletin 1994;; 106 (3): 351–370. doi: https://doi.org/10.1130/0016-7606(1994)106<0351:EAIOPS>2.3.CO;2 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 SocietyGSA Bulletin Search Advanced Search Abstract Inflated pahoehoe sheet flows have a distinctive horizontal upper surface, which can be several hundred meters across, and are bounded by steep monoclinal uplifts. The inflated sheet flows we studied ranged from 1 to 5 m in thickness, but initially propagated as thin sheets of fluid pahoehoe lava, generally 20-30 cm thick. Individual lobes originated at outbreaks from the inflated front of a prior sheet-flow lobe and initially moved rapidly away from their source. Velocities slowed greatly within hours due to radial spreading and to depletion of lava stored within the source flow. As the outward flow velocity decreases, cooling promotes rapid crustal growth. At first, the crust behaves plastically as pahoehoe toes form. After the crust attains a thickness of 2-5 cm, it behaves more rigidly and develops enough strength to retain incoming lava, thus increasing the hydrostatic head at the flow front. The increased hydrostatic pressure is distributed evenly through the liquid lava core of the flow, resulting in uniform uplift of the entire sheet-flow lobe. Initial uplift rates are rapid (flows thicken to 1 m in 1-2 hours), but rates decline sharply as crustal thickness increases, and as outbreaks occur from the margins of the inflating lobe. One flow reached a final thickness of nearly 4 m after 350 hr. Inflation data define power-law curves, whereas crustal cooling follows square root of time relationships; the combination of data can be used to construct simple models of inflated sheet flows.As the flow advances, preferred pathways develop in the older portions of the liquid-cored flow; these pathways can evolve into lavatube systems within a few weeks. Formation of lava tubes results in highly efficient delivery of lava at velocities of several kilometers per hour to a flow front that may be moving 1-2 orders of magnitude slower. If advance of the sheet flow is terminated, the tube remains filled with lava that crystallizes in situ rather than draining to form the cave-like lava tubes commonly associated with pahoehoe flows.Inflated sheet flows from Kilauea and Mauna Loa are morphologically similar to some thick Icelandic and submarine sheet flows, suggesting a similar mechanism of emplacement. The planar, sheet-like geometry of flood-basalt flows may also result from inflation of sequentially emplaced flow lobes rather than nearly instantaneous emplacement as literal floods of lava. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.