USGS Preliminary Analysis_LERZ_7-15-18_v1.1

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Both delta collapse and hydrovolcanic explosions are hazards primarily to boats and other water craft, as this area is currently closed to foot traffic. Based on an extensive study of these coastal hazards during the 35 -year eruption of the Pu'u '0'6 vent, a zone of radius 300 m is considered a minimum high hazard around pahoehoe lava deltas (Mattox and Mangan, 1997; Hawaiian Volcano Observatory, 2017). The 2018 Kapoho lava delta is composed of 'a'5 lava and more study will be required to ascertain whether this high hazard margin needs to be modified. Figure 7. Photo of the laze plume from the fissure 8 ocean entry (leftmost incandescence) lit by the source fountain (rightmost incandescence) and lava channel. White lights to the far right are from Pahoa. Photo taken on the evening of June 20, 2018 by Klaus Hodapp. Laze (lava haze) plume The large laze plume (fig. 7) produced at the ocean entry poses a health risk to those exposed to it. It will continue as long as lava enters the ocean. The composition of the plume is the result of the interaction between molten basaltic lava and sea water and includes hydrochloric acid, hydrofluoric acid, and halide precipitate. It is not known how far downwind harmful constituents drift in a laze plume of this size. At times onshore winds carry the laze plume an unknown distance inland. How long will this eruption last? The current eruption started with 23 days of sporadic eruption from 24 different fissures covering a distance of 6.7 km (4.2 mi), some composed of multiple segments, before focusing at fissure 8, which has been erupting continuously since May 27. More than 430 x 106 m3 of lava has been erupted so far (as of July 15). Most of this volume has come from fissure 8, which is discharging lava at an estimated rate of about 100 m3/s. This exceeds the duration (38 days), erupted volume (122 x 106 m3 of lava), and peak time -averaged eruption rate (38 m3/s; for the first 2 week) of the 1960 eruption. While the current eruption has not yet lasted as long as the 1955 eruption (88 days, including pauses), it has erupted far more lava at a higher rate—the 1955 eruption produced 81 x 106 m3 of lava at a peak time -averaged discharge rate of 31 m3/s (for the first phase of the 1955 eruption). In this regard, the current eruption may be more similar to the 1840 eruption, which, though only lasting for 26 days, erupted 210 x 106 m3