On May 31, 1954, a lava fountain erupting higher than the crater rim and the “lava fall” cascading down the northeastern crater wall quickly covered the entire floor of Halema`uma`u Crater with incandescent lava. A line of small fountains (upper right) on the Kilauea Caldera floor northeast of Halema`uma`u is nearly obscured by volcanic fume.

(Volcano Watch is a weekly article and activity update written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.)

After more than 18 months of dormancy, Kilauea Volcano erupted early on the morning of May 31, 1954. The eruption was not specifically predicted, but it was not unexpected.

During the previous year, tilting along Kilauea’s northeastern caldera rim suggested increased pressure beneath the summit. Periods of volcanic tremor also indicated movement of magma within the volcano.

Given these signals, Hawaiian Volcano Observatory scientists reported to the U.S. Geological Survey in 1953 that, “Under such conditions, eruption might come with very little forewarning.” And that’s exactly what happened.

At 3:42 a.m. HST on May 31, an earthquake woke residents near Kilauea Caldera, including HVO scientists Gordon Macdonald and Jerry Eaton. Shortly afterward, Macdonald noticed a faint, but persistent, low-pitched humming or roaring noise—almost a felt vibration rather than a recognizable sound.

During the next 12 minutes, several more earthquakes occurred, with the strongest at 3:54 a.m. Throughout these earthquakes, Kilauea remained dark, with no signs of eruption.

At 4:09 a.m., HVO seismographs recorded the onset of volcanic tremor. One minute later, Macdonald and Eaton observed a bright glow at Halema`uma`u Crater. The glow was reflected on a gas plume that was rising to a height of about 600 m (2,000 ft) above the crater rim and still expanding upward.

By 4:20 a.m., a column of fume nearly obscured the top of a lava fountain erupting from the northeastern part of Halema`uma`u. This fountain rose 30 m (100 ft) above the crater rim, and its total height was almost 180 m (600 ft) above the crater floor.

The eruption was initially confined to Halema`uma`u Crater. But around 4:30 a.m., a line of fissures opened on the floor of Kilauea Caldera about 90 m (300 ft) northeast of Halema`uma`u.

The primary fissure, originally about 90 m (300 ft) long, rapidly lengthened—mostly eastward, but also slightly westward toward Halema`uma`u—and, within 20 minutes, it was 430 m (1,400 ft) long. At first, incandescent lava welled gently from this fissure, but gradually, lava fountains grew to heights of 15–30 m (50–100 ft).

Four other shorter fissures, located from 60 to 550 m (200 to 1,800 ft) east-northeast of the primary fissure, also erupted small lava fountains less than 6 m (20 ft) high.

Spatter quickly accumulated along the fissures, building ramparts and small cones, while frothy pieces of pumice drifted southwestward on trade winds. Lava flows—the first on Kilauea’s caldera floor since 1921—advanced both north and south of the fissures, at times breaching the spatter ramparts.

When Macdonald and Eaton reached the rim of Halema`uma`u Crater at 4:55 a.m., the entire floor was covered with incandescent lava, and an erupting fissure extended across the crater. Lava fountains ranged in height from less than a meter (3 ft) to 180 m (600 ft), with the most vigorous activity at the northeast and southwest ends of the fissure.

A spectacular feature of the 1954 eruption was the cascade of brilliant yellow-orange lava that poured from a crack in the northeastern wall of Halema`uma`u Crater. This “lava fall” plunged 90 m (300 ft) to the crater floor, where it joined a pool of lava at the base of the high northeastern fountain.

Within hours, lava had accumulated in Halema`uma`u Crater to a depth of more than 15 m (50 ft). But around noon, part of the fluid pond began draining back into the fissure, leaving a slump scarp of congealed lava clinging to the crater walls like a bathtub ring and forming a prominent sinkhole on the crater floor.

By mid-morning on May 31, the eruptive activity greatly decreased, both within Halema`uma`u Crater and on the caldera floor. Weak spattering from small fountains and sporadic showers of pumice, mostly within Halema`uma`u, continued until nightfall on June 3, when all activity ceased.

At the end of this brief, 3.5-day-long eruption, new lava left in Halema`uma`u Crater was, on average, about 9 m (30 ft) thick, and lava flows covered about 56 hectares (139 acres) of the caldera floor. Subsequent summit eruptions buried many of these features, but some evidence of Kilauea’s 1954 eruption—remnants of the spatter rampart and lava flows on the caldera floor—are still visible today.