Subsurface architecture of two tropical alpine desert cinder cones that hold water

Matthias Leopold, Amanda Morelli, Norbert Schorghofer

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    3 Citations (Scopus)

    Abstract

    Basaltic lava is generally porous and cannot hold water to form lakes. Here we investigate two impermeable cinder cones in the alpine desert of Maunakea volcano, Hawaii. We present the results of the first ever geophysical survey of the area around Lake Waiau, the highest lake on the Hawaiian Islands, and establish the existence of a second body of standing water in a nearby cinder cone, Pu‘upōhaku (~4000 m above sea level), which has a sporadic pond of water. Based on unpublished field notes from Alfred Woodcock (*1905–†2005) spanning the years 1966–1977, more recent observations, and our own geophysical survey using electric resistivity tomography, we find that perched groundwater resides in the crater perennially to a depth of 2.5 m below the surface. Hence, Pu‘upōhaku crater hosts a previously unrecognized permanent body of water, the highest on the Hawaiian Islands. Nearby Lake Waiau is also perched within a cinder cone known as Pu‘uwaiau. Among other hypotheses, permafrost or a massive block of lava were discussed as a possible cause for perching the water table. Based on our results, ground temperatures are too high and specific electric resistivity values too low to be consistent with either ice-rich permafrost or massive rock. Fine-grained material such as ash and its clay-rich weathering products are likely the impermeable material that explains the perched water table at both study sites. At Pu‘uwaiau we discovered a layer of high conductivity that may constitute a significant water reservoir outside of the lake and further be responsible for perching the water toward the lake.
    Original languageEnglish
    Pages (from-to)1148-1160
    Number of pages13
    JournalJournal of Geophysical Research: Earth Surface
    Volume121
    Issue number6
    DOIs
    Publication statusPublished - Jun 2016

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