Volcano Watch: Kilauea summit eruptions outside of Halema驶uma驶u
We are used to seeing eruptions from the summit region of Kilauea contained to the region that is referred to as Halema‘uma‘u. Halema‘uma‘u, home of Pele, is a crater situated within the larger, steep-walled caldera at the summit of Kilauea named Kaluapele. While eruptions at the summit of Kilauea most frequently occur within Halema‘uma‘u, they can occur outside of the modern caldera as well.
Kilauea summit eruptions in the past several decades have been confined to Halema‘uma‘u. Starting in 2008 a decade-long lava lake formed within Halema‘uma‘uthat drained during the 2018 caldera collapse. This was replaced for a year and a half by a water lake, which in turn was destroyed during the December 2020 eruption, and since then there have been multiple Halema‘uma‘u eruptions of which the ongoing lava fountaining just reached episode 45 on April 23, 2026. But further back in time, many eruptions at Kilauea’s summit occurred outside of Halema‘uma‘u.
The earliest written documentation of summit eruptions outside of the caldera occurred in 1832 and 1868, both of which were to the east of Kaluapele. The best documented and observed summit eruption to not occur within Halema‘uma‘u is the episodic lava fountaining eruption in 1959 at Kilauea Iki that formed Pu‘upua‘i — the prominent cone visible from the Devastation Trail. This eruption occurred to the east of the Kaluapele boundary, and was the subject of a “Volcano Watch” on Jan. 8, 2026.
Eruptions in August 1971, July 1974, and September 1982 occurred south of the caldera rim. In fact, for those that are familiar with the Keanakako‘i overlook that provides spectacular viewing of the ongoing episodic lava fountaining events, spatter and lava that erupted from the fissure systems for the August 1971 and July 1974 eruptions are right at this location. 91直播 Volcanoes National Park has interpretative signs here that date back to when Crater Rim Drive in this area was still open to motorists.
The August 14, 1971, eruption near Keanakako‘i lasted for around 10 hours and its lava flow cascaded over the caldera rim and flowed to below Volcano House. The July 19-22, 1974, eruption lava flows also cascaded over the caldera rim before solidifying below Volcano House. However, a lobe of this lava flow also cascaded into the bottom of Keanakako‘i Crater and continued to flow farther south and east before the eruption ceased.
The Sept. 25, 1982, eruption lasted for about 15 hours. This eruption’s fissure system is located in the south caldera region about a mile (approximately 1.6 kilometers) from the Keanakako‘i overlook within a part of the national park that is closed as a result of the high volcanic hazard. Its associated lava flow reaches to within 700 yards (approximately 630 meters) of the Keanakako‘i overlook, but is also within the closed, high hazard part of the national park; this lava flow also cascaded over the caldera rim.
Each of the fissure systems that fed these eruptions spanned hundreds of yards (hundreds of meters), with the lava fountains themselves remaining relatively low. Portions of both fissures from the August 1971 and July 1974 eruptions were lowered along with the caldera floor during the collapse that occurred in 2018. Despite subsiding, these fissures remained relatively intact. However, the recent lava fountaining episodes that started on Dec. 23, 2024, have continued to generate lava flows that cover this area intermittently. This has resulted in new lava flows completely covering the August 1971 fissure and portions of the July 1974 fissure on the crater floor.
The remaining parts of the August 1971 and July 1974 fissures and their associated lava flows are visible around the Keanakako‘i viewing area with interpretative signs along the trail on the side of the road opposite of Keanakako‘i Crater.
These eruptions outside of Halema‘uma‘u in the past are evidence that such eruptions could also occur in the future. Most eruptions in new locations are preceded by an increase in shallow seismicity related to magma movement. While not analogous to the precursory seismic activity from the 1970s and 1980s, there has been recent shallow earthquake activity and ground deformation along the south rim of Halema‘uma‘u — highlighted in a “Volcano Watch” on April 23, 2026.
The ongoing earthquakes beneath Kilauea’s summit are not currently indicative of an imminent eruption along the south rim of Halema‘uma‘u, but they are a reminder that the area is dynamic and can experience a variety of volcanic hazards. The USGS 91直播an Volcano Observatory will continue to closely monitor Kilauea — a very active volcano where changes can occur quickly across the summit region and beyond.
Volcano activity updates
Kilauea has been erupting episodically within the summit caldera since Dec. 23, 2024. Its USGS Volcano Alert level is ADVISORY.
Episode 45 of summit lava fountaining happened for 8.5 hours on April 23. Summit region inflation since the end of episode 45 indicates that another fountaining episode is possible; current models suggest that episode 46 could start between Tuesday, May 5, and Saturday, May 9. No unusual activity has been noted along Kilauea’s East Rift Zone or Southwest Rift Zone.
Mauna Loa is not erupting. Its USGS Volcano Alert Level is at NORMAL.
One earthquake was reported felt in the 91直播an Islands during the past week: a M3.5 earthquake 0 km (0 mi) WSW of Pahala at 31 km (19 mi) depth on April 28 at 9:26 a.m.
Please visit HVO’s website for past Volcano Watch articles, Kilauea and Mauna Loa updates, volcano photos, maps, recent earthquake information, and more. Email questions to askHVO@usgs.gov.
