Case Study · Volcanic Eruption · 2018
May–August 2018. Kīlauea's Lower East Rift Zone erupted — the most destructive volcanic event in Hawai'i in 200 years. 35.5 square kilometers buried under lava. Over 700 structures destroyed. 48 kilometers of road gone. The Puna Geothermal Venture — 31% of the Big Island's electricity — shut down. Most destroyed homes were in USGS Lava Flow Hazard Zones 1 and 2. Hawaii has published these maps since 1974. The Lower Puna District had erupted in 1955 and 1960. Zero people died directly from lava. The evacuation worked. The property losses were the predictable consequence of a documented, decades-old decision.
Lower Puna District, Island of Hawai'i · May–August 2018
The 2018 Kīlauea eruption in the Lower East Rift Zone is, in a specific and important sense, the most predictable major volcanic disaster in recent US history. USGS publishes Lava Flow Hazard Zone maps for the entire Island of Hawai'i, dividing the land into nine zones based on eruption probability. The USGS HVO account of the 2018 eruption documents what the LERZ represents in this system: Zone 1 is active rift zone territory — the areas with the highest eruption frequency and direct vent exposure. The subdivisions that experienced the worst 2018 destruction — Leilani Estates, Lanipuna Gardens, and neighboring areas in lower Puna — were developed in Zone 1 and Zone 2. The Lower Puna District had erupted in 1955, destroying 9 homes. It erupted again in 1960, covering the town of Kapoho with lava. The 35-year Pu'u'Ō'ō eruption ran from 1983 to 2018, intermittently threatening lower Puna communities throughout. The 2018 eruption was not a surprise geological event. It was the latest in a documented series of rift zone eruptions in exactly the area where the destroyed homes were built.
The USGS account of the 2018 eruption documents the scale: "An area of 35.5 square kilometers (over 8,700 acres) was covered with lava, which includes the addition of 875 acres of new land created near the eastern extent of the Island of Hawai'i. Residents were displaced as lava covered over 700 structures and 48 kilometers (30 miles) of road." The more comprehensive Bulletin of Volcanology damage assessment found 1,839 structures destroyed and 90 damaged. The Puna Geothermal Venture (PGV) — which generated 31% of the Big Island's electricity in 2017 — was temporarily shut down. Lava covered two of its wells. 900 utility poles were destroyed; power restoration for isolated properties took months. Volcanic gas emissions reached the highest levels ever recorded at Kīlauea; vog (volcanic smog from SO2 interactions with sunlight and moisture) affected areas as far as Guam.
And yet: zero people died directly from lava flows. The USGS monitoring network at the Hawaiian Volcano Observatory provided real-time tracking of fissure openings, lava channel locations, and flow front advance. Civil defense ordered evacuations of at-risk areas. The evacuations worked. The lesson of Kīlauea 2018 is not about monitoring failure or warning failure — both functioned as designed. The lesson is about the gap between knowing a location is in a high volcanic hazard zone and acting on that knowledge in property, insurance, and community development decisions before an eruption forces the point.
May–Aug 2018
Duration
700+
Structures Destroyed
35.5 km²
Covered by Lava
Zones 1 & 2
Most Destroyed Homes
0
Direct Lava Deaths
The Science
Think of Kīlauea and Mauna Loa as the two active volcanic systems that have defined the Big Island's surface. The entire land area of the island is former lava — the question is only how recently a given area last erupted and how likely it is to erupt again. USGS divides the island into nine Lava Flow Hazard Zones reflecting this probability. Zone 1 covers the active rift zones and summit areas — places where eruptions occur most frequently, sometimes annually. Zone 2 is adjacent to Zone 1 and has significant historical eruption frequency. Zones 3 through 9 reflect decreasing eruption probability. The Nature Communications research on the 2018 eruption references the standard USGS map from 1992: "Map showing lava-flow hazard zones, Island of Hawaii. U.S. Geol. Surv. Misc. F. Stud. Map MF-2193." This map, and its predecessors and successors, have been publicly available and freely accessible for decades. The LERZ area where the 2018 eruption occurred had erupted in 1955 and 1960 before the subdivisions were built. The Bulletin of Volcanology damage assessment of the 2018 eruption documents the historical context explicitly: a map of post-1950 lava flows that have erupted along the East Rift Zone — showing 1955, 1960, 1969-1974, 1983-2018, and 2018 flows, all in overlapping geography.
The Bulletin of Volcanology damage assessment of the 2018 eruption documents infrastructure impacts beyond destroyed homes. The Puna Geothermal Venture (PGV) plant, which generated 31% of the Big Island's electricity, was shut down when lava approached. Two of its wells were covered. Power was disconnected from at-risk areas by Hawaiian Electric Light Company (HELCO) as a safety measure. 900 utility poles were destroyed. Power was not restored to isolated homes until months after the eruption ended. The PGV did not reopen until November 2020 — over two years after the eruption. The USGS HVO account of the eruption notes: "nearly 200,000 metric tons of SO2 being emitted each day of the 2018 lower East Rift Zone eruption" — the highest ever recorded at Kīlauea, producing vog that affected the entire state and areas as far as Guam. The 2018 eruption demonstrates that lava flow events in developed areas cascade through electrical infrastructure, road networks, water systems, and energy generation in ways that persist long after lava stops flowing.
The Tandf research on the 2018 eruption summarizes the key characteristic of lava flows relative to other volcanic hazards: "Lava flows from volcanoes can significantly destroy infrastructure, although they rarely threaten human life." Lava flows move slowly enough — even the channel flow from Fissure 8, which traveled 13 km from vent to ocean, did so over days and weeks — that evacuated communities can survive a lava event even when everything they owned was destroyed. The USGS damage assessment methodology, documenting the first formal damage state classification system for lava flows, found that building damage was directly related to lava flow thickness: above approximately 2 meters (6.6 feet), all buildings were destroyed; below that, damage varied. The critical insight for preparedness: lava flow evacuation is effective at saving lives even when it cannot save property. The zero-death outcome of the 2018 eruption occurred in the context of massive property destruction. Both outcomes are the predictable result of known hazard zones and effective — if not preventive — emergency management.
Timeline
01
1983: Pu'u'Ō'ō eruption begins on middle East Rift Zone — the longest and most voluminous eruption in Kīlauea's history, which would run for 35 years. Lower Puna communities live with the active volcano. Lava flow hazard zone maps published; Lower Puna's LERZ in Zones 1-2. April 30, 2018: the Pu'u'Ō'ō crater floor collapses, sending magma into the lower East Rift Zone. Ground swelling detected in the LERZ. HVO issues alerts. May 3: fissures begin opening in Leilani Estates subdivision — directly on the rift zone. Mandatory evacuation orders issued. Lava fountains reach several hundred feet. Toxic sulfur dioxide gas forces evacuation of nearby areas.
02
May: 24 fissures open across the LERZ over three weeks. Puna Geothermal Venture (PGV) shut down as lava approaches; two wells covered. Mandatory evacuation of areas in lava flow paths. Late May/early June: Fissure 8 emerges as the dominant vent, producing a sustained 80-meter lava fountain and developing a major channelized lava river. Channel extends 13 km from vent to ocean at Kapoho Bay. Kapoho Bay — a beloved snorkeling destination — is completely filled with lava, destroying the Wai'ōpae Tidepools. Lava flow advance tracked daily by HVO with aerial thermal imaging and ground observation. 900 utility poles destroyed; power disconnected from at-risk areas.
03
May–August 2018: lava inundates 35.5 km². 700+ structures destroyed (comprehensive count: 1,839 destroyed, 90 damaged, of 3,165 total assessed). 48 km of road covered. 875 acres of new land created where lava entered the ocean. Vog (volcanic smog from SO2 and sunlight reaction) blankets the Big Island and spreads as far as Guam. SO2 emissions: highest ever recorded at Kīlauea. Most destructive volcanic event in Hawai'i in 200 years — the previous comparable event was the 1790 Kīlauea explosive eruption. Properties in lava hazard zones but outside direct inundation zones became inaccessible as lava blocked roads. August: Fissure 8 activity declines. September 4, 2018: eruption effectively ends.
04
Direct deaths from lava: zero. One injury from a lava bomb (molten lava fragment launched from the channel). Displaced residents: thousands; some permanently. PGV reopened November 2020. Insurance challenges: many homeowners in high lava hazard zones had difficulty obtaining or affording standard homeowners insurance, or were underinsured relative to replacement costs. Discussions of lava zone insurance, disclosure requirements, and building restrictions intensified post-2018. Federal disaster declaration for Hawai'i County. USGS HVO enhanced monitoring and public communication protocols. The 2018 eruption is the most fully documented lava flow event in history — HVO took 8,000+ aerial and ground photographs for the comprehensive damage assessment.
Human Decisions
The development decision
The lower Puna District of Hawai'i offers lower land and home prices than areas of the Big Island in lower hazard zones — a market reflection of the volcanic risk. Subdivisions like Leilani Estates and Lanipuna Gardens developed through this price differential, offering relatively affordable land in a state with extremely high housing costs. Residents who purchased in these areas generally knew they were in volcanic hazard zones; Hawaii requires hazard zone disclosure in real estate transactions. The decision to develop and purchase in Zone 1 was not made in ignorance of the maps. It was made with the maps — accepting the risk in exchange for affordability. What the 2018 eruption made visible was the specific consequence of that decision: when the eruption came, it came for exactly the homes and infrastructure the hazard maps had always said were most at risk. Knowing the hazard zone is the prerequisite for making an informed choice about where to live. The 2018 eruption is the case study for what the highest hazard zone means when the hazard arrives.
Many homeowners in lower Puna's highest lava hazard zones found it difficult or impossible to obtain standard homeowners insurance — or found that coverage excluded volcanic hazard, or found that coverage limits were far below replacement costs. The 2018 eruption forced this gap into visibility: thousands of households facing total property loss with inadequate or no insurance coverage. The Hawaii homeowners insurance market in high lava zones reflects the actuarially accurate risk — a Zone 1 property has historically erupted multiple times per century. Standard insurance underwriting reflects this risk in premiums and exclusions. For residents in volcanic hazard zones nationally — including in the Cascade Range states where volcanic risk exists at lower probability — understanding whether homeowners insurance covers volcanic events (it varies by policy and state), what the exclusions are, and whether additional coverage is available is directly applicable post-2018 preparedness.
What the zero-death outcome required
The USGS Hawaiian Volcano Observatory provided real-time tracking of every aspect of the 2018 eruption: which fissures were active, where lava channels were developing, how fast flow fronts were advancing, and where lava was expected to go next. The USGS thermal map dataset of the eruption includes over 8,000 aerial photographs documenting the dynamic evolution of the lava flow field. Civil defense authorities used this information to issue and update evacuation orders — progressively expanding the evacuation zones as the eruption developed and the flow field changed. The system worked: nobody died from direct lava exposure. The monitoring infrastructure that produced the zero-death outcome was built from decades of experience with Kīlauea's eruption behavior — the same kind of institutional volcanic knowledge that was absent in Colombia in 1985 and present in the Philippines in 1991.
The 2018 evacuation was not only about lava. Fissure 8's eruption produced SO2 emissions that were immediately life-threatening at close range — the USGS HVO account documents the "highest levels ever recorded at Kīlauea." Residents who ignored or delayed evacuation orders faced not only lava flow threat but also toxic volcanic gas. The specific danger of SO2: at concentrations above 5 parts per million, it causes respiratory distress; above 100 ppm, it is immediately dangerous to life and health. The lava channel from Fissure 8 also produced laze — a corrosive mixture of hydrochloric acid steam and tiny glass particles — where lava entered the ocean. The Kapoho Bay area was not accessible during active ocean entry due to laze hazard. Evacuation from a lava zone event is not just about the lava itself; it is about the full envelope of hazards that accompany active lava flow events.
The cascade lesson
The 2018 Kīlauea case study defines the lava flow hazard zone lesson: property in a high volcanic hazard zone is always at risk of exactly the kind of loss that occurred in 2018. The hazard maps don't predict when an eruption will occur — Kīlauea's Lower East Rift Zone had not erupted since 1960 before it erupted in 2018. What the maps predict is where lava will go when the eruption comes. For residents of the Big Island — and, by analogy, for anyone in a documented hazard zone of any kind — the 2018 eruption is the demonstration of what hazard map documentation means in practice.
What You Can Do Now
Kīlauea 2018's lesson applies most directly to Big Island residents and anyone considering property in a volcanic hazard zone. These five actions address the documented gap between knowing and acting on volcanic hazard information.
USGS and the State of Hawaii maintain lava flow hazard zone maps for the entire Island of Hawai'i. The zone for any specific parcel can be found through the Hawaii County Real Property Tax website (qpublic.net/hi/hawaii or county property records) or directly through USGS HVO's lava flow hazard zone maps at hvo.wr.usgs.gov. Hawaii requires hazard zone disclosure in real estate transactions — any legitimate real estate transaction on the Big Island should include the specific lava zone classification. Zone 1 and Zone 2 represent the highest risk; the 2018 eruption concentrated its destruction there. Zone 9 (most of the Kohala Coast, areas of Kona) is the lowest risk. The zone classification directly affects insurance availability, mortgage requirements, and evacuation planning.
Hawaii lava flow hazard zone lookup guideStandard homeowners insurance policies in the US often exclude or significantly limit volcanic eruption coverage. In states where volcanic hazard is real but lower-probability (Oregon, Washington, California, Idaho, Wyoming/Yellowstone area), reading your policy's volcanic exclusion carefully and asking your insurer specifically about lava, pyroclastic flow, lahar, and ashfall coverage is important. In Hawaii's high lava zones, specialized volcanic coverage is available but may be expensive. Mortgage lenders for properties in documented volcanic hazard zones may require specific coverage. The 2018 eruption left many homeowners with inadequate coverage — understanding this gap before an event is the preparedness action.
Volcanic event homeowners insurance guideKīlauea's summit eruption has produced ongoing vog across the Big Island for extended periods. SO2 and its reaction products cause respiratory irritation, asthma exacerbation, and other health effects. During the 2018 LERZ eruption, SO2 levels in some areas were immediately life-threatening. Preparation for vog: N95 respirators or better (P100 respirators provide better protection against volcanic particulates including SO2 reaction products); air purifiers with activated carbon filters for indoor air quality; keeping windows and doors closed during high-vog periods; awareness of which areas of the island are typically higher or lower vog concentration based on wind patterns. Hawaii County Civil Defense provides SO2 and vog monitoring data online.
Volcanic air quality preparedness guideThe 2018 evacuation worked partly because many residents in lower Puna had lived through years of Pu'u'Ō'ō lava flow threats and had evacuation experience. For those newer to volcanic hazard zones: identify the roads out of your area that avoid river valleys and low-elevation channels where lava would flow; know which roads connect to higher ground; identify friends, family, or lodging options in Zones 7-9 or off the Big Island; and have a go-bag ready for rapid departure. Lava flow events can develop rapidly once a rift zone eruption begins — the 2018 eruption progressed from initial fissure opening to active subdivision lava flows within days.
Volcanic evacuation route planning guideUSGS Hawaiian Volcano Observatory (hvo.wr.usgs.gov) publishes daily activity updates, eruption notifications, hazard assessments, and real-time monitoring data for Kīlauea and Mauna Loa. During the 2018 eruption, HVO published daily — sometimes hourly — updates on lava flow front locations, fissure activity, SO2 levels, and evacuation guidance. Signing up for USGS Volcano Notification Service emails and following Hawaii County Civil Defense on official channels provides the same information stream that enabled the zero-death outcome in 2018: real-time hazard data from the scientists who track the volcano continuously, communicated to residents who need to make evacuation decisions.
USGS HVO monitoring and alert guideVolcanic Eruption case study series
Mount St. Helens 1980 covers the defining US volcanic event. Armero 1985 covers lahars and the warning-to-action gap. Pinatubo 1991 covers the most successful volcanic evacuation in history. Eyjafjallajökull 2010 covers volcanic ash's global aviation and supply chain disruption.
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