Volcano Watch — Kīlauea flows continue without interruption

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The eruption along Kīlauea's east rift zone continues without interruption. Following the last pause in activity in the middle of April, the tube was reoccupied from the vent 51 and 53 areas adjacent to the Pu'u 'O'o cone to just above Paliuli, upslope from Kamoamoa. New surface flows formed above Paliuli and reached the sea along a broad front, with major entries near both the east and west edges of the Kamoamoa flow field. Within a few days, the eastern entry died out, and the main flows were along the boundary between the Laeapuki flow that formed in April 1993 and the main part of the Kamoamoa flows.

Much of the lava delta below Paliuli has been covered by new lava within the last month as the flows established a new tube system below Paliuli. This tube is now established, and the main flow is entering the ocean within less than 0.5 miles of the end of Chain of Craters Road inside Hawaii Volcanoes National Park. The lava viewing is quite good from the end of the road and requires minimal walking. The best viewing is at dusk, when the steam plume is underlit by the glowing lava, and the small explosions send sprays of incandescent lava into the air. During the day, when conditions are favorable, National Park Rangers are leading hikes to nearby active surface flows.

The lava pond inside Pu'u 'O'o is unchanged, with an active surface and some spattering, mainly along the eastern end of the pond. The pond is still very deep, with the surface nearly 275 feet below the lowest point on the rim. During the last week, there have been times when the glow was diminished; these probably represent short periods when the pond surface crusted over or when there was little cloud cover to reflect the glow from the pond surface.

The lava flux (volume per unit time) has been fluctuating during the last month, but at times it was as great as we have measured during the last 8 years of this 11-year-long eruption. The maximum fluxes have been greater than 600,000 cubic meters per day (nearly 800,000 cubic yards per day), and the minimum about half that amount. It was not clear whether the flux changed rapidly or slowly, since we usually measured it only once or twice each week. To find out, we measured the flux every hour for a 21-hour period and found that it varied from hour to hour, with the maximum about 600,000 cubic meters per hour and the minimum about 400,000 cubic meters per hour. These variations also correspond to changes in the strength of the tremor (continuous ground shaking) recorded at a seismic station near Pu'u 'O'o, though there is a two-hour delay between the stronger tremor and the larger lava flux. This delay represents the time it takes the lava to flow within the tube from the vents to the site where we measure the lava flux at a skylight in the tube.

The summit of Kīlauea is deflating slowly, which means that the amount of lava erupting is slightly greater than the amount of new magma that migrates up into the magma chamber from a deep source in the Earth. This deflation is measured by carefully measuring the elevation of the summit region or by measuring small changes in the slope (tilt) of the ground. Throughout most of the 11 years of this eruption, the summit has deflated or sunk slowly as more lava has erupted than has moved into the magma chamber to replace it. Due to this net withdrawal of magma from the summit magma chamber, the summit region has sunk about four feet during the eruption.