Report on Kilauea (United States) — 25 April-1 May 2018
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
25 April-1 May 2018
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2018. Report on Kilauea (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 25 April-1 May 2018. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
During 25 April-1 May HVO reported that the lava lake continued to rise, fall, and spatter in Kilauea’s Overlook crater. The lake level was high enough to produce lava flows onto the Halema'uma'u crater floor through 27 April, but afterwards fell to about 15-16 m below the new elevated rim. The lake level rose again, to just below the rim of the Overlook crater vent. Since 21 April about 2/3 of the crater floor had been covered by new lava flows.
Episode 61g lava flows were active above Pulama pali, within 2 km of the active vent. A marked increase in seismicity and ground deformation at Pu'u 'O'o Crater was detected just after 1400 on 30 April, following weeks of uplift and increasing lava levels within the cone. Within a few minutes a webcam on the crater rim recorded the first of two crater floor collapses; the second collapse began at 1520 and lasted about an hour. Thought poor weather conditions inhibited views at times, a webcam recorded what were likely small explosions from the W side of the crater as the floor collapsed. At 1800 seismicity remained elevated, though ground deformation had significantly slowed. A large amount of red ash was produced from the collapses, and deposited around the crater as well as in areas up-rift as far as Mauna Ulu.
Following the collapses of Pu'u 'O'o’s crater floor, seismicity and deformation increased along a large section of the East Rift Zone, in an area 9-16 km down-rift (with seismicity occurring as far E as highway 130), indicating an intrusion of magma. By 0830 on 1 May activity had significantly decreased. During an overflight that day a new, nearly continuous, 1-km-long crack was found on the W (up-rift) side of Pu'u 'O'o. The crack was steaming, and aligned in a segment with small pads of newly-erupted lava and spatter. Thermal images of Pu'u 'O'o Crater suggested that smaller drops of the crater floor likely continued on 1 May.
Geological Summary. Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the island of Hawaii. Eruptions are prominent in Polynesian legends; written documentation since 1820 records frequent summit and flank lava flow eruptions interspersed with periods of long-term lava lake activity at Halemaumau crater in the summit caldera until 1924. The 3 x 5 km caldera was formed in several stages about 1,500 years ago and during the 18th century; eruptions have also originated from the lengthy East and Southwest rift zones, which extend to the ocean in both directions. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1,100 years old; 70% of the surface is younger than 600 years. The long-term eruption from the East rift zone between 1983 and 2018 produced lava flows covering more than 100 km2, destroyed hundreds of houses, and added new coastline.