EPISODE 33

"Two more episodes of the 2.5-year-old middle E rift zone eruption occurred 12-13 June and 6-7 July. Episode 33 was both preceded and followed by continuous low-level activity at the vent. Spattering was first observed on 1 June and continued intermittently until 12 June at 0430, when a low dome fountain produced a thin pahoehoe flow that extended 0.25 km from the vent. Fountaining ended after 20 minutes, but was followed by 20 more periods of low fountaining over the next 19 hours. At 2306 on the 12th, continuous high fountaining began. The high fountains persisted for almost 6 hours and produced a single aa flow that extended 4.5 km SE from the vent, overriding an earlier (episode 32) flow.

"Following episode 33, magma was continuously visible in the conduit, and by 20 June spatter was again reaching the conduit rim. Episode 34 began on 6 July at [1903] and ended 14 hours later, producing an aa flow that terminated 3 km SE of the vent.

Deformation. "The Uwekahuna tiltmeter began recording subsidence on 12 June at 2200, approximately 1 hour before continuous high fountaining began. Summit subsidence continued for 17 hours, resulting in a net loss of 7.0 µrad. Reinflation of the summit began slowly then increased rapidly after 22 June; by the end of the month, the summit tilt had regained 6.7 µrad. Deformation data for episode 34 had not been reduced at the time of this report.

Seismicity. "Harmonic tremor began with a minor increase in amplitude on 12 June at 0430, recorded by the Kamoamoa seismic station 1 km W of Pu`u `O`o. Tremor amplitude increased rapidly at 2230 and remained high until 0452 on 13 June. The intensity of eruption tremor subsided rapidly thereafter, marking the end of vigorous lava fountaining. Moderate-amplitude tremor was recorded in the summit region until about 1600 on the 13th.

"The number of short-period caldera, or summit, earthquakes increased gradually in May then decreased from 1 June until the onset of the eruptive episode on 12 June. Intermediate-depth (5-13 km), long-period events were persistent throughout the month. Shallow long-period events at the summit accompanied the deflation event and eruptive episode on 12-13 June."

Accident. "On 12 June, George Ulrich, staff geologist at HVO, and Dario Tedesco, a volcanologist from the Osservatorio Vesuviano, were collecting lava samples and making temperature measurements at Pu`u `O`o vent. A low dome fountain from Pu`u `O`o was feeding a short flow to the SE. George was standing on the edge of the lava channel on solid but recently formed crust. At 1430, after completing a temperature measurement (1,137°C), he walked onto the older lava to return the thermocouple and gather a sampling pick. When he returned to the lava channel to obtain a sample, the pahoehoe river had stopped moving, and he inadvertently went past the stable recent crust onto even more recent crust, which then gave way. He went in over his field boots, and was unable to pull himself out. In the attempt to reach for safety, his knees made further contact with the molten lava. Within an estimated 5 seconds, Dario pulled him to safety. His outer clothing (NOMEX suit) was then burning, but quickly extinguished itself. At the time of the accident, a helicopter piloted by Bill Lacey was landing to deliver an extra time-lapse camera. George got into the helicopter under his own power and Bill Lacey flew him directly to Hilo hospital. George was subsequently transferred to the Straub Clinic in Honolulu, where the following evaluation was made one week after the accident: first degree burns over parts of arms, hands, and face, healing normally; second degree burns from ankles to uppermost thighs on both legs; third degree burns on left kneecap, extending to upper thigh, and possible third degree burns on right kneecap. The long-term prognosis is for full recovery with no permanent disabilities, as none of the burns affected the musculature of the legs."

[George Ulrich returned to work part-time after a 2-month hospital recovery. After a few weeks, he resumed full-time responsibilities. Within 5 months, after achieving more than 90% recovery, he returned to full-time field work.]

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: C. Heliker, R. Hanatani, R. Koyanagi, HVO.