Tephra accumulation and wind data for Kīlauea’s 2008–2018 lava lake eruption

The 2008–2018 summit eruption at Kīlauea formed an active and slowily expanding lava lake within Halemaʻumaʻu Crater that lasted 10 years before draining. To consistently collect proximal tephra ejected from the lava lake, which was nested within the new, informally named “Overlook crater,” a network of ten plastic buckets was established early and emptied on most days of the eruption thereafter. These data represent the results of more than 2,400 different sampling intervals (most 1–3 days long) during the eruption. The network was distributed within about 300 meters south of the vent to capture tephra dispersed by the dominant northeast trade wind. The juvenile tephra mainly reflected spattering at the southeast sink, a downwelling area in the southeastern part of the lava lake in the Overlook crater that remained in the same area throughout the eruption. Lithic tephra consisting of solid rock and secondary minerals derived from the wall of the crater are also found. The proportion of juvenile to lithic material ranged widely early in the eruption but was generally above 90 percent for the last 6 years of the eruption as lake level rose and the crater walls lowered and became more stable. The accumulation rate of tephra at each bucket was strongly dependent on the location of the bucket and reflects the interplay between lava lake level and wind direction and speed. The mass per unit area (m/a) of collected tephra was a maximum of about 97 kilograms per square meter for the entire eruption, equivalent to a thickness of about 75 millimeters. Thirty-two explosive events with a volcanic explosivity index of -2 to -4 deposited much of the tephra in the network. Fifteen of these rock-fall-induced events occurred within 6 days of one another. Pele’s hair, a volcanic glass predominantly associated with more placid activity at the vent in the final half of the eruption, was dispersed more than 60 kilometers downwind from the lava lake and formed a nearly continuous deposit near the Overlook crater. This eruption was probably the most frequently sampled long-lasting eruption in history, but most of the deposits are ephemeral. The collected samples, though generally of small mass, are retained by the Hawaiian Volcano Observatory and are available for detailed study.