Hawai‘i Volcanoes National Park on Hawai‘i Island was set to temporarily close Halemaʻumaʻu Trail and part of Byron Ledge Trail by 5 p.m. Wednesday, Oct. 7, due to safety around continued inflation and earthquake activity at the summit of Kīlauea Volcano.
The trail closure totals 1.3 miles.
Citing the U.S. Geological Surveyʻs Hawaiian Volcano Observatory, HVNP said in an announcement Wednesday that more than 200 shallow earthquakes occurred below the Kīlauea summit last week — and six more have occurred in the last 24 hours.
"A magnitude 3.4 earthquake at 9:52 p.m. on Sept. 30 caused small rockfalls along the north wall of the caldera," the park says. "The increased seismicity could trigger additional rock falls and presents a serious safety risk. Both trails descend from the caldera rim to the floor and have been the site of dangerous rock falls in the past."
HVNP says that Kīlauea is "highly pressurized and while forecasting is not possible due to the irregularity in inflation and deflation, changes could occur quickly at the summit."
"HVO scientists report that additional cracks have opened on the caldera floor between Uēkahuna and Wahinekapu (Steaming Bluff), likely due to a short-lived magma intrusion to the area Sept. 30 to Oct. 1," the park noted.
You can read the most recent Kīlauea status update from HVO here.
Kīlauea has been erupting intermittently since Dec. 23, 2024, largely from two vents in Halema‘uma‘u crater within the summit caldera. According to USGS, there have been 54 eruptive episodes between that date and Aug. 25, when 4 million cubic meters of lava erupted during a nine-hour eruptive episode, episode 54.
USGS notes, too, that between Sept. 14 and 16, six new vents opened in and near the base of the northwest wall of Halemaʻumaʻu crater and erupted lava flows on the crater floor without fountaining.
While "HVO suggests lava fountains could resume within Halemaʻumaʻu crater from the north-south-west vent complex," HVNP says in Wednesdayʻs announcement that the 43 days since Aug. 25 mark the longest period of time without lava fountains since the eruptive cycle began.
"It is also possible that another magma intrusion could occur and cause an eruption along the weak crack system at the summit," the announcement notes.
According to the park, viewing areas on the Keanakākoʻi side of the caldera closed for safety last week; with the closest parking about a mile from the overlooks, the area is difficult to evacuate quickly.
Visitors are required to stay out of closed areas and away from cliff edges which are unstable and can collapse without warning, HVNP says.
More geological changes
Unrelated to the ongoing eruption, HVNP also announced earlier this month that the iconic Hōlei Sea Arch, located at the end of Chain of Craters Road within the park, had collapsed into ocean sometime in late September. An Oct. 1 announcement noted that the 90-foot sea arch was standing on Sept. 23 but had collapsed by Sept. 27, although the exact time of the collapse is unknown and could have happened when the park was temporarily closed during Tropical Storm Nolo.
"The coastline flanking the sea arch has shown signs of instability for years," that announcement noted. "Earthquakes during the 2018 Kīlauea eruption and summit collapse damaged the cliffs near the arch and in January 2020, new cracks and instability prompted the park to close the original viewing area. A safer viewing area further from the cliff edge opened in March 2020. Later that year, massive surf from Tropical Storm Darby broke off a chunk of rock from the lower part of the arch."
According to the park website, the sea arch was cut into the cliff of an ancient lava flow from about 550 years ago due to "differential erosion."
Stephanie Salmons can be reached at stephanie@alohastatedaily.com.
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