A Third Pond on the Mauna Kea Summit Plateau

Abstract: Few ponds are found in the permeable volcanic landscape of Hawaii. After Hurricane Lane passed close to Hawaii Island in August 2018, causing record rainfalls, a pond temporarily emerged on the Mauna Kea summit plateau that had never been reported before. We characterize the pond using satellite observations and electrical resistivity tomography. The shallow pond is located on glacial till 3,594 m a.s.l., and was visible for less than 1 week. The geophysical survey, carried out 10 months after the pond's appearance and disappearance, revealed a layer of low electrical resistivity at depths of about 1–3 m below the surface, which, based on laboratory analysis, likely represents a perennial body of water well protected from evaporation. The existence of a third pond, in addition to Lake Waiau and Pu‘upōhaku Pond, in the previously glaciated area suggests perching layers are not uncommon. Montmorillonite, a 3-layer shrink-swell clay that can help to perch water, was identified in the Lake Waiau area. Mineral analysis on surface samples of the third pond did not reveal such a clay mineral.