HVO reported that increased seismicity and deformation at Kilauea began at around 1200 on 2 June and likely indicated that magma was rising. Rates of seismicity and deformation increased further after 1700, prompting HVO to raise the Volcano Alert Level to Watch (the third level on a four-level scale) and the Aviation Color Code to Orange (the third color on a four-color scale) at 1731. Activity decreased slightly by 2230 but remained at elevated levels. About 250 earthquakes in total were located beneath the summit region, though in the previous few hours before the Alert Level change, some were located beneath the upper East Rift Zone. The largest earthquakes included a M 4 event recorded at 1907 and a M 4.1 event recorded at 2112. Most events occurred at depths of 2-3 km, though several were located slightly shallower, at a depth of about 1.5. The earthquakes were widely felt in Hawai?i Volcanoes National Park and surrounding communities and triggered many rockfalls.

A new eruption began at around 0030 on 3 June from fissures located in a remote area along the Southwest Rift Zone, about 1-2 km S of the caldera and N of the Koa’e fault system and Hilina Pali Road, within Hawai'i Volcanoes National Park. At 0211 the Volcano Alert Level was raised to Warning and the Aviation Color Code was raised to Red. Incandescence from the eruption was visible in webcam images. During an overflight at 0600 volcanologists observed that four fissures had sequentially propagated from the ENE to WSW. Lava fountaining occurred along the fissure and gas plumes were drifting SW. The eruption was producing a low volume of lava; at 0827 the Volcano Alert Level and Aviation Color Code were lowered to Watch and Orange, respectively. At around 0745 sulfur dioxide emissions averaged 15,000 tonnes per day (t/d), decreased to 12,000 t/d by 1200, and likely decreased further during the afternoon. Earthquake activity in the summit region had greatly decreased with the onset of the eruption; all seismicity during 0700-1500 was concentrated near Maunaiki, at the westernmost fissure segment. Slow summit deflation had started at around 0200 and was ongoing. Lava flows were slow during 1100-1200 and had ceased moving by 1230, indicating that the eruption has ceased or paused. By 1500 volcanic tremor, a signal associated with fluid movement, continued to be recorded on summit seismometers though at a slightly decreased intensity. Gas emissions decreased and by noon on 4 June they averaged 5,500 t/d. Volcanic tremor continued to be recorded on summit seismometers, though earthquake activity and rates of ground deformation remained low in the summit region and upper rift zone areas. Incandescence from the fissures was visible overnight. The most recent eruption in that area occurred in December 1974.

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.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)