"In September, lava continued to enter the ocean in the Laeapuki area . . . . The W branch of the tube on the bench stopped transporting lava, and flows entering the ocean consolidated in front of the 27 July littoral cone. Littoral explosions increased in size and frequency coincident with the consolidation of the littoral tube system. On 14 September, ~10-15 m of the active bench collapsed into the ocean. The bench built out into the ocean until 1 October, when part of the active bench collapsed again. Flows built a small, thick bench following each collapse. Near the end of September, the flux at this ocean entry appeared to diminish, possibly because of the diversion of lava to a prolific E flow. Lava continued to enter the ocean in this area until 5 October, when the eruption paused for the first time since April.

"The large surface flow that broke out on 20 August at 270 m elevation continued to cover new land on the E side of the Kamoamoa flow-field. Throughout most of September there were active breakouts on this flow from the base of Pulama pali to below Paliuli. All of these breakouts were fluid pahoehoe toes and sheet flows. Sheet flows on the E margin of the flow field frequently ignited methane explosions, which were recorded by the Wahaula seismometer. Breakouts began to close the gap between the Kamoamoa and Kupaianaha flows; <200 m separated the two flow fields. Lava from this E flow entered the ocean on the E side of the Kamoamoa flow field intermittently during 2-9 October.

"Two pauses in October were only the 4th and 5th to occur since E-53 began in February 1993. On 6 October, all surface activity stopped, no lava entered the ocean, and there was no lava in the tube system. By the following morning lava had reoccupied the tube all the way to the Laeapuki ocean entry and fed breakouts close to 270 m elevation. Lava also continued to ooze and dribble into the ocean on the E side of the flow field. Following this pause, a number of breakouts were observed on Pulama pali and on the E flow. Lava entering the ocean in the Laeapuki area began to build a new bench E of the littoral cone formed on 27 July. Lava from the E flow entered the ocean once again on 22 October. On 24 October, the eruption appeared to be sputtering — flows slowed and then surged, entries died and then reactivated. By 25 October, all surface activity had stagnated. The eruption restarted the following day, and this time the tube system was reoccupied to only 550 m elevation. Below this elevation, large channelized aa and pahoehoe flows swept down the flow field. By 31 October, these flows had cascaded over Paliuli and begun to make their way to the ocean.

"Pu`u `O`o pond was a little more dynamic during this interval. From 13 September to 6 October, the pond level slowly dropped from 79 to 88 m below the crater rim. At its lowest level, the entry of lava from the W side of the pond was clearly visible. In October, the pond level rose from 88 to 60 m below the crater rim and activity on the pond surface became more vigorous. There was little change around the active vents, except that the collapse pit on the W flank of Pu`u `O`o doubled in size during September."

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.

Information Contacts: T. Mattox, HVO.