The 2018 lower Puna eruption was a volcanic event on the island of Hawaiʻi, on Kīlauea volcano's East Rift Zone that began on May 3, 2018. It is related to the larger eruption of Kīlauea that began on January 3, 1983, though some volcanologists and USGS scientists have discussed whether to classify it as a new eruption. Outbreaks of lava fountains up to high, lava flows, and volcanic gas in the Leilani Estates subdivision were preceded by earthquakes and ground deformation that created cracks in the roads.
On May 4, a 6.9 magnitude earthquake hit Puna. By May 27, 2018, 24 fissures had erupted lava in and near the Leilani Estates and Lanipuna Gardens subdivisions. The eruption forced the evacuation of approximately two thousand residents. The Puna Geothermal Venture, which provided one-quarter of the island's electricity, was forced to shut down and was later damaged by lava. The fissures had sent lava rivers that buried part of Hawaii Route 137 on May 19, and began flowing into the ocean.
On May 29, lava from a new northeastern flow overran Hawaii Route 132, cutting the access between Kapoho and Pāhoa. The massive lava flow reached the Pacific Ocean at Kapoho Bay on June 4. Lava entered the Kapoho Crater and evaporated Green Lake, which had been the largest natural freshwater lake in Hawaiʻi. On the night of June 4–5, the northeastern flow of lava speedily moved forward and destroyed the subdivision of Vacationland Hawaii. By June 5, Kapoho Bay had been filled in with lava now forming a point where the bay had been. The volcanic activity was the most destructive in the United States since the 1980 eruption of Mount St. Helens.
By August 7, of land had been covered by lava flows. About of new land has been created in the ocean. The official number of houses destroyed by the eruption reached 700 on July 9. It was estimated that recovery efforts would cost more than $800 million (2018 USD). By early August the eruption had almost completely subsided, and on December 5, it was declared to have ended after three months of inactivity.
Background
The volcanic event in Puna was the 62nd episode of Kīlauea's east rift zone eruption that began in January 1983. Puʻu ʻŌʻō had become a prominent volcanic cone east of the summit caldera of Kīlauea, since the 1983 eruption's beginning. In the 1980s and 1990s, Puʻu ʻŌʻō produced lava flows that destroyed the nearby Royal Gardens subdivision and the settlement of Kapaʻahu. In 1990, lava flows from the Kūpaʻianahā vent of Kīlauea, downrift from Puʻu ʻŌʻō, destroyed and partly buried most of the nearby towns of Kalapana and Kaimū.
On April 30, 2018, the crater floor of the cone of Puʻu ʻŌʻō collapsed and the summit lava lake level in Halemaʻumaʻu dropped significantly. In the first two days of May, hundreds of small earthquakes were detected on Kīlauea's East rift zone, leading officials to issue evacuation warnings for some residents of the Puna District. On May 2, 2018, the US Geological Survey reported that ground deformation resulting from magma intruding beneath the Leilani Estates subdivision had caused ground cracks to form on roads in and around the subdivision.
In connection with the eruption and its possible effects on the Hilina Slump, the Hawaiian Volcano Observatory published information concluding that the chance of a catastrophic collapse would be incredibly remote.
Eruption
Earthquakes and Leilani Estates fissures
On May 3, 2018, after a 5.0 earthquake earlier in the day, steaming ground cracks opened in Leilani Estates and began to spew lava, causing evacuations of the Leilani Estates and Lanipuna Gardens subdivisions. The outbreak marked the beginning of the 62nd episode of the east rift zone eruption that began in January 1983. That evening, Hawaii Governor David Ige activated the state National Guard to help with the evacuation process.
The next day, May 4, two homes were reported destroyed in Leilani Estates from three erupting vents. The Hawaii County Civil Defense Agency reported high levels of toxic sulfur dioxide gas in the area, and Talmadge Magno, the Civil Defense Administrator for Hawaiʻi County, stated that power lines had melted off poles from the heat. The Puna Geothermal Venture (PGV), a power station, was shut down on 22 May 2018; the geothermal power plant provided approximately 25% of the Big Island's power, but its shutdown was later stated not to present a risk to power on the island. A Temporary Flight Restriction area was declared by the FAA to restrict flights below 3,000 feet AGL in the eruption area.