Kīlauea is one of the most frequently erupting volcanoes on Earth. During the modern era, it has produced dozens of eruptions, and from 1983 to 2018 it erupted almost continuously for 35 years straight. Since the dramatic caldera collapse of 2018, the volcano has returned to a pattern of shorter eruptions separated by months of quiet, with new events in 2020, 2023, and 2025. But the story of Kīlauea’s eruptive frequency stretches back millennia, and the pace of its activity has not always looked the way it does today.
Centuries of Shifting Behavior
Kīlauea’s activity over the past 2,500 years can be divided into roughly five major periods, alternating between centuries dominated by effusive eruptions (the relatively gentle lava flows most people picture) and centuries dominated by explosive eruptions at the summit.1Geology. Cycles of explosive and effusive eruptions at Kīlauea Volcano, Hawai’i Each of these phases lasted several hundred years. The volcano’s current effusive period began around the 1820s, when Western observers first arrived, and has been the backdrop for every eruption captured by modern science. Before that, Kīlauea spent roughly three centuries in an explosive phase, during which summit eruptions hurled ash and rock rather than pouring out lava flows.
This matters for understanding eruption frequency. During effusive periods, eruptions happen often and produce large volumes of lava, sometimes nearly without pause. During explosive periods, eruptions are less frequent but far more dangerous. The magma supply rate during those explosive centuries drops to roughly one to two percent of what it is during effusive times.2GeoScienceWorld Books. Magma supply to Kīlauea Volcano, Hawai’i, from inception to now So when people ask how often Kīlauea erupts, the honest answer depends on which century you’re talking about.
The Modern Eruptive Record
Since reliable observations began in the early 1800s, Kīlauea has erupted more than 60 times. For most of the 19th and early 20th centuries, the pattern was relatively conventional for an active volcano: eruptions every few years, separated by quiet intervals. Some of these historical eruptions were mislocated or misunderstood for over a century. Three 19th-century fissure eruptions along the northeastern edge of the summit caldera, in 1832, 1868, and 1877, had their vent locations significantly corrected only in 2020 when researchers revisited the original accounts and field evidence.3ScienceDirect. Correcting the historical record for Kīlauea Volcano’s 1832, 1868, and 1877 summit eruptions The fact that vent locations were wrong for well over a hundred years gives you a sense of how much our understanding of even “recent” eruptions continues to evolve.
Through the mid-20th century, Kīlauea produced a series of eruptions that scientists studied closely, including summit events in 1952, 1959, and 1967–68, and rift zone eruptions in 1955, 1960, and 1969–74. These events provided the first combined observations of eruption rate and ground deformation, allowing researchers to estimate that the volcano received magma from below at a roughly steady rate of about 0.11 cubic kilometers per year during three sustained eruptions from 1952 to 1971.2GeoScienceWorld Books. Magma supply to Kīlauea Volcano, Hawai’i, from inception to now Later work has complicated that picture, suggesting the supply rate has varied by as much as tenfold over historical time, but the basic finding helped establish Kīlauea as a natural laboratory for understanding how volcanoes are fed.
The Long Eruption at Pu’u ‘Ō’ō
In January 1983, a new eruption began on Kīlauea’s East Rift Zone, building a cone called Pu’u ‘Ō’ō. What started as a series of episodic lava fountains settled into nearly continuous lava production that lasted until 2018, making it one of the longest-lived eruptions in Kīlauea’s recorded history. The shift from episodic fountaining to continuous flow was driven by a subtle change in how efficiently the volcanic plumbing system retained heat.4Journal of Volcanology and Geothermal Research. The 1983–86 Pu’u ‘O’o eruption of Kilauea Volcano, Hawaii: a study of dike geometry and eruption mechanisms for a long-lived eruption Once the conduit feeding the eruption stayed hot enough, lava could flow steadily rather than building up pressure and releasing it in bursts.
During those 35 years, Kīlauea was effectively always erupting. Lava from Pu’u ‘Ō’ō poured across the landscape, burying communities, entering the ocean, and building new land. For anyone living on Hawai’i Island during that era, the question was not “how often does Kīlauea erupt” but rather “when will it stop.” The eruption reshaped the southeastern coastline, creating submarine lava deltas that contained more than half the total erupted volume, with much of the lava deposited below sea level.5Bulletin of Volcanology. Submarine lava deltas of the 2018 eruption of Kīlauea volcano
The 2018 Eruption and Caldera Collapse
In May 2018, the long-running East Rift Zone eruption took a dramatic turn. New fissures opened in the lower Puna district, far downslope from Pu’u ‘Ō’ō, sending fast-moving lava through residential neighborhoods. At the summit, the lava lake in Halema’uma’u crater drained, and the caldera itself began to collapse. Over the following months, the summit sank by hundreds of meters in a sequence of repeated collapse events, each accompanied by earthquakes around magnitude 5.6Geophysical Research Letters. Anatomy of a Caldera Collapse: Kīlauea 2018 Summit Seismicity Sequence in High Resolution
The collapse began after less than four percent of the magma had drained from a shallow reservoir beneath the summit, reducing internal pressure by about 17 megapascals. Several cubic kilometers of magma had been stored in the reservoir, and only a fraction was withdrawn before the eruption ended.7PubMed. Magma reservoir failure and the onset of caldera collapse at Kīlauea Volcano in 2018 That finding surprised researchers: it demonstrated that caldera collapse can begin after only a small percentage of magma is removed, meaning these dramatic events do not require the reservoir to empty out.
The 2018 eruption ended in August of that year, and Kīlauea entered a genuine quiet period for the first time in decades. But the quiet did not last long. A new eruption began inside the collapsed summit crater in December 2020, producing a lava lake. Since then, the volcano has erupted several more times in short bursts, most recently in early 2025. The current pattern is a return to the pre-1983 rhythm: eruptions lasting weeks to months, separated by pauses.
Where Eruptions Happen on Kīlauea
Kīlauea’s eruptions are not random. They concentrate in three areas: the summit caldera and two rift zones radiating outward like arms. The more active of the two is the roughly 60-kilometer-long East Rift Zone, which has hosted most of the major eruptions of the past century, including both the Pu’u ‘Ō’ō eruption and the 2018 lower Puna event. The Southwest Rift Zone, about 30 kilometers long, is quieter but still capable of eruptions.8ScienceDirect. Origins and nature of large explosive eruptions in the lower East Rift Zone of Kīlauea volcano, Hawaii
The rift zones are not just cracks in the surface. They are zones of weakness where magma intrudes laterally from the summit reservoir, sometimes traveling tens of kilometers underground before reaching the surface. This means an eruption can start with inflation and earthquakes at the summit, then break out many kilometers away. The 2018 sequence illustrated this perfectly: magma drained from beneath Halema’uma’u and traveled down the East Rift Zone to emerge in the lower Puna district, roughly 40 kilometers from the summit.
The Connection to Mauna Loa
Kīlauea sits on the southeastern flank of Mauna Loa, the much larger shield volcano next door, and the two share a deep magma source in the Hawaiian hotspot. Over the past century, their activity has been strangely anti-correlated: when one volcano is erupting frequently, the other tends to be quiet. This led to speculation that they compete for the same magma supply, with one volcano essentially starving the other.
Numerical modeling has offered a more specific explanation. The two volcanoes have separate plumbing systems in the upper crust, but they appear to be coupled deeper down through pressure changes in a shared zone of partially molten rock in the upper mantle. When one volcano erupts and releases pressure, the resulting shift in pore pressure can inhibit eruptions at the other, unless the overall magma supply increases enough to feed both simultaneously.9Nature Geoscience. Coupling at Mauna Loa and Kīlauea by stress transfer in an asthenospheric melt layer This explains an otherwise puzzling observation: during the past decade, both volcanoes inflated at the same time, and Mauna Loa erupted in November 2022 for the first time since 1984, even while Kīlauea was active. The coupling is real but not a simple seesaw.
For anyone watching Kīlauea’s eruption frequency, the Mauna Loa connection is worth keeping in mind. A major eruption at Mauna Loa could, under the right conditions, delay Kīlauea’s next eruption, or an increase in deep magma supply could fire up both volcanoes in quick succession.
How Scientists Know an Eruption Is Coming
Kīlauea is one of the most intensively monitored volcanoes on the planet, and the decades of data have given scientists practical tools for forecasting eruptions, even if perfect prediction remains out of reach. Two signals stand out. Ground tilt, measured by networks of instruments around the summit, shows the surface rising and falling as magma enters or leaves the shallow reservoir. Locally elevated tilt values are strongly associated with upcoming eruptions, even when the overall long-term trend is steady. Filtering out the long-term inflation and focusing on short-term spikes dramatically improves forecasting accuracy.10Journal of Geophysical Research. Eruption forecasting at Kilauea Volcano, Hawaii
Earthquake swarms at the summit are the other major red flag. Clusters of small earthquakes often precede eruptions by hours to days, and the number of located earthquakes tends to spike sharply right before an eruption begins.10Journal of Geophysical Research. Eruption forecasting at Kilauea Volcano, Hawaii The combination of tilt anomalies and earthquake swarms gives the Hawaiian Volcano Observatory enough lead time to issue warnings, though the exact timing of an eruption’s start can still surprise even experienced volcanologists by hours or days.
Gas emissions provide another layer of information. Sulfur dioxide measurements at Halema’uma’u crater, for example, have shown that gas output increases significantly during periods of elevated seismic activity beneath the caldera.11Journal of Geophysical Research: Solid Earth. Variation in sulfur dioxide emissions related to earth tides, Halemaumau Crater, Kilauea Volcano, Hawaii Subtle variations in gas flux have even been linked to tidal cycles, suggesting that the gravitational tugging of the moon and sun can modulate the volcano’s outgassing at the margins.
When Kīlauea Turns Explosive
The gentle image of Kīlauea as a lava-flow volcano can be dangerously misleading. As the centuries-long cycle of activity shows, Kīlauea has spent long periods in an explosive mode. The most famous historical example occurred in 1790, when a series of explosive eruptions killed a group of Hawaiian warriors crossing the summit area. Geological evidence and survivor accounts recorded 46 years later describe a harrowing sequence: first, a cloud of darkness from very fine, wet ash bearing accretionary lapilli; then a rain of rock fragments from a high eruption column visible from 90 kilometers away; and finally, pulsing currents of hot gas and debris sweeping across Kīlauea’s western flank.12GeoScienceWorld (GSA Bulletin). Reconstructing the deadly eruptive events of 1790 CE at Kīlauea Volcano, Hawai’i Footprints left in the soft ash deposit are still preserved today.
Phreatic eruptions, driven by the interaction of hot rock and groundwater, are the mechanism behind these explosive events. The trigger requires two conditions: a large volume of magma must drain from the summit reservoir, and magma near the surface must be rapidly removed, exposing superheated rock to groundwater that flashes to steam.13Bulletin of Volcanology. Mechanism of explosive eruptions of Kilauea Volcano, Hawaii Either condition alone is not enough. Large magma transfers in 1955 and 1960 did not produce explosions because the near-surface magma was not rapidly withdrawn. Lava lake draining events in 1922 and 1923 also failed to trigger explosions because the subsurface conditions were not right. Only when both factors align does Kīlauea produce the kind of violent eruptions that the 1790 event represents.
The 2018 caldera collapse briefly raised the question of whether explosive activity might return, since the lava lake drained and the summit reservoir lost pressure rapidly. Small rockfall-driven explosions did occur, throwing blocks out of the crater, but nothing approaching the scale of the 1790 events materialized. The current effusive period appears to be holding, though the geological record is a reminder that centuries-long shifts in eruption style have happened before and will happen again.
Living with Vog
Even when Kīlauea’s eruptions are gentle by volcanic standards, they are not harmless. The volcano is a prolific source of sulfur dioxide, which reacts with moisture and sunlight in the atmosphere to form volcanic smog, locally known as “vog.” During the decades-long Pu’u ‘Ō’ō eruption, vog was a chronic fact of life for communities on the island’s leeward side, where trade winds trap the haze.
When Kīlauea’s gas output spiked in 2008, researchers found significant increases in clinic visits for cough, headache, sore throat, and acute airway problems during weeks of high vog exposure, when ambient sulfur dioxide levels averaged about three times higher than baseline. The risk was unevenly distributed: young Pacific Islanders experienced more than a sixfold increase in odds for acute airway problems.14PubMed. Acute health effects associated with exposure to volcanic air pollution (vog) from increased activity at Kilauea Volcano in 2008 A broader population survey confirmed that vog exposure was tied to higher rates of cough, phlegm, runny nose, shortness of breath, sinus congestion, wheezing, and eye and skin irritation, along with measurably higher blood pressure and lower blood oxygen levels.15ISRN Public Health. Adverse Health Effects Associated with Increased Activity at Kīlauea: A Repeated Population-Based Survey
These are not exotic risks for a faraway population. Hundreds of thousands of people live on Hawai’i Island, and vog regularly drifts to neighboring islands. When Kīlauea is actively erupting, particularly at the summit where gas emissions are highest, the air quality can deteriorate rapidly with little warning. The eruption frequency question, then, is not just geological curiosity: it directly determines how often communities must cope with degraded air.
Microbes in the Steam Vents
Kīlauea’s relentless activity has also created unusual habitats. The volcano’s steam vents, where heat and volcanic gases seep through the surface, host communities of microorganisms that thrive in conditions hostile to most life. Highly altered volcanic glass inside active steam vents at Kīlauea contains subsurface bacteria smaller than 500 nanometers in diameter, with tiny mineral grains attached directly to their cell walls. Above these subsurface communities, green biofilms of filamentous cyanobacteria coat the surface, themselves encrusted with nanoscale amorphous silica particles.16CrossRef API. Microbial mediation of authigenic clays during hydrothermal alteration of basaltic tephra, Kilauea Volcano These organisms are not just surviving passively; they appear to actively mediate the formation of clay minerals from the volcanic rock, essentially helping to turn fresh lava into soil at a microbial scale. The ongoing volcanic activity is what sustains these environments, and the frequency of eruptions ensures a constant supply of fresh, chemically reactive rock for the microbes to colonize.
On a larger scale, the 2018 lava flows have provided researchers with a chance to study ecological recovery from scratch. Early surveys of the hardened lava fields show that wind-dispersed seeds from nearby surviving forests are the primary driver of plant recolonization, with proximity to intact forest being the strongest predictor of where vegetation returns first.17Digital Commons. Lava to Leaf: Remote Sensing of Post-Eruption Ecological Succession on the 2018 Kīlauea Lava Flows Kīlauea’s frequent eruptions mean that the Hawaiian landscape is a patchwork of lava flows at different stages of recovery, from bare black rock to dense forest, with the age of the underlying flow determining how far succession has progressed. It is one of the best natural laboratories on Earth for watching life rebuild from nothing.