In the summer of 2018, Kīlauea’s summit caldera collapsed more than 1,600 feet deep as magma drained to feed the lower East Rift Zone eruption, exposing lava flows and tephra sections unseen since the Hawaiian Volcano Observatory was founded in 1912.
The 2018 collapse exposed deposits from some of the oldest eruptions ever cataloged near Kīlauea’s summit — layers that had remained hidden for more than a century.
This article covers the geological story behind those newly exposed walls — what the tephra layers reveal, how scientists accessed them between lava fountain episodes, and where you can see similar volcanic landscapes yourself at Hawaiʻi Volcanoes National Park. The caveat: these particular exposures were re-buried by lava flows within eight years, so the science is a race against time, not a permanent exhibit.
Geology enthusiasts
National park visitors
Science-curious families
Kīlauea’s Shield-Building Stage: A 200,000-Year-Old Foundation
Kīlauea has been in its shield-building stage for longer than 200,000 years. Most of the volcano is covered by young lava flows less than 1,000 years old, which means few samples, observations, or data exist for older eruptions — especially at the summit. That’s what made the 2018 collapse so significant: it cut a 1,640-foot (500-meter) deep crater where Halemaʻumaʻu once sat, a hulihia (dramatic change) that exposed layers of lava and tephra not seen since the Hawaiian Volcano Observatory first opened.
Those new exposures preserved deposits from some of the oldest eruptions scientists have ever cataloged near Kīlauea’s summit. For geologists at the Hawaiian Volcano Observatory, it was like opening a time capsule they’d never been able to reach before.
Mapping the Caldera Walls by Drone
After the 2018 collapse, HVO geologists collected high-resolution photographs of the west wall of Kaluapele using uncrewed aircraft systems (drones). They stitched the images into a large mosaic of the caldera cliff south of Uēkahuna — the highest point on Kīlauea. From that mosaic, several sections of explosive tephra were identified, sandwiched among the lava flows.
The drone work gave scientists a bird’s-eye map of where to focus their fieldwork. Without it, locating specific tephra layers in a 1,600-foot-deep crater would have been guesswork.
HVO collected hundreds of overlapping images of the west wall and assembled a photomosaic identifying tephra sections among the lava flows. This step determined where the field teams would go.
Starting spring 2026, HVO staff monitored rising lava in Halemaʻumaʻu approaching a second tephra section. Episodic lava fountain forecasting allowed safe fieldwork during pauses between episodes — specifically between episodes 50 and 51. Geologists traversed fresh lava flows to reach the caldera wall.
The tephra exposure sat about 20 feet (6 meters) above the caldera floor. Over a few hours, the crew described and sampled the lava flows and tephra layers preserved in the crater walls. Each sample offers a unique glimpse of summit eruptive history unavailable anywhere else on the volcano.
Episode 51, a week later, sent lava flows north along the western crater wall, raising the surface of Halemaʻumaʻu to just beneath the tephra sequence. Episode 52 in late July did the same. An overflight on July 29 confirmed the tephra was buried again — exposed for less than eight years total.
The Tephra Time Machine: What the Layers Reveal
One of the largest tephra sections identified in the new caldera walls was partially exposed in the early 19th century. Thomas Jaggar last documented it in July 1913, and it was buried by the 1919 summit eruption a few years later. Re-exposed in 2018, HVO scientists now wonder if it could be associated with the Uēkahuna Ash — deposits dated to 1–2 thousand years old — since it sits at a similar level in the caldera walls to other exposures further north in Kaluapele.
The tephra exposures visited in 2023 and 2026 are lower and could be much older than the Uēkahuna Ash. That means they could represent eruptions never before studied. Sample analysis will help determine when and how they erupted, providing insight into a murky period of Kīlauea’s eruptive history that has no written records and few preserved deposits anywhere else on the volcano.
Practical Considerations for Visiting Kīlauea’s Caldera
You won’t see the tephra layers themselves — they’re buried again under fresh lava flows from episodes 51 and 52. But the caldera walls at Kaluapele remain a dramatic landscape shaped by the same volcanic processes. Hawaiʻi Volcanoes National Park is open year-round, and the current eruption (ongoing since December 23, 2024) means you may see lava fountaining from safe viewpoints along Crater Rim Drive or at the Kīlauea Overlook.
Safety and Access
The USGS Volcano Alert level for Kīlauea remains at ADVISORY as of August 2026. Episode 54 of lava fountaining occurred on August 25 for 9 hours. Summit region inflation resumed initially after the episode but was followed by variable ground deformation. Another episode is likely in coming weeks if normal tilt patterns resume. The park adjusts viewpoints and trail access based on activity — check the current conditions page before you go.
What You Actually See
From the caldera rim, you look down into Kaluapele — the 1,600-foot-deep collapse crater formed in 2018. Dark lava flows on the western wall are from recent fountaining episodes. The vent complex is visible in the background. The tephra exposures that geologists sampled are now buried, but the wall itself tells the same story: layer upon layer of lava and explosive deposits stacked over millennia, exposed by a single dramatic collapse.
Visit the Kīlauea Visitor Center first — rangers give eruption updates and can point you to the best viewpoint for current activity. The Jaggar Museum overlook, closed since 2018, is no longer accessible, but the Uēkahuna overlook area offers a comparable perspective of the caldera’s west wall where the drone surveys were done.
Volcanic fumes (vog) can shift with wind direction, especially near the caldera rim. The park posts air quality alerts at entrance stations and visitor centers. Anyone with respiratory conditions should carry a mask and check conditions before heading out on trails.
Before You Go — Kīlauea’s Volcanic Landscapes
Can I see lava right now?
Possibly. Kīlauea has been erupting episodically within the summit caldera since December 2024. Episodes last several hours and are separated by days of pause. Check the park’s eruption notification page or the USGS Kīlauea update for the latest episode timing.
How much time do I need at the park?
A half-day covers Crater Rim Drive and the Kīlauea Visitor Center. A full day lets you add the Chain of Craters Road down to the coast, where 2018 lava flows meet the sea — completely different from the summit landscape but part of the same eruption sequence.
Is the park safe for kids?
Yes, with standard precautions. Stay on marked trails and behind all barriers — the caldera rim has no guardrails in places. The visitor center has a junior ranger program that explains volcanic geology at a kid-friendly level.
What’s the one downside people don’t mention?
The tephra layers that made this article possible are gone — buried by new lava within eight years of being exposed. If you’re coming specifically to see the 2018 collapse exposures, you’re about six years too late. The caldera itself is still spectacular, but the science window closed fast.
The Landscape That Keeps Rewriting Itself
Kīlauea doesn’t preserve its history neatly — it buries it, covers it, and occasionally digs it back up when the ground drops a thousand feet. The tephra layers that HVO geologists sampled in 2023 and 2026 are already back under lava, but the same process will eventually expose others as Halemaʻumaʻu’s floor rises. Each sample gives scientists a glimpse of summit eruptive history that exists nowhere else on the volcano.
For a broader look at Hawaii’s volcanic and coastal landscapes, check out our guide to moss and lava falls in Hawaii’s wild spaces — a different kind of erosion story, shaped by water rather than collapse.
References
Lynn, Kendra J. “Volcano Watch: The tephra time machine — exploring Kilauea’s past.” Hawaii Tribune-Herald, August 30, 2026. ↗
Lynn, Kendra J. “Volcano Watch: The tephra time machine — exploring Kīlauea’s past.” Maui Now, August 30, 2026. ↗
If you’re planning a trip to see Kīlauea’s active landscapes, our guide to affordable adventures in Hawaii covers park fees, nearby lodging, and how to make the most of a day at Hawaiʻi Volcanoes National Park without overspending. For a completely different kind of geological journey, the Road to Hana takes you through eroded sea cliffs and waterfall-carved valleys that tell their own story of water versus rock.
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