Lava moving toward the ocean from the recent eruption at Kilauea.
Photo: AP

Kilauea’s largest eruption in at least 200 years may be over, but scientists are still learning about how it reshaped Hawaii’s Big Island. Case in point: We now have a map showing just how high the lava piled up.

Last week, scientists with the USGS Hawaii Volcano Observatory (HVO) released a preliminary map showing the thickness of the recently cooled lava flows blanketing Kilauea’s lower East Rift Zone. We already knew that the eruption spilled at least 300,000 Olympic swimming pools of lava over 13.7 square miles of land, but this is the first map to show how much of a topographic boost regions impacted by the eruption received.

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The map shows that the most dramatic changes occurred offshore. As lava spewed out of cracks in the Earth and raced down molten rivers into the sea, it piled up to form a delta up to 919 feet thick, ultimately adding 875 acres (1.4 square miles) of fresh turf to the coastline.

“That’s quite a lot,” Adam Soule, a volcanologist at the Woods Hole Oceanographic Institution who spent some time last year mapping these offshore lava flows, told Earther. He noted that parts of this delta would rise more than halfway up the Empire State building.

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Image: USGS

Despite the prodigious pileup, the new land isn’t necessarily going to be stable over the long-term.

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Soule said that if you were to walk on the delta right now—and you should not do this—it would feel just like walking over cooled lava anywhere else on the island. Beneath this barren moonscape, however, sits a lot of fragmented material that has the potential to collapse under the right circumstances; for instance, if an earthquake were to shake things up.

While the topographic changes on land were less dramatic, some parts of the lower East Rift Zone have been irrevocably altered by the lava that oozed out of two dozen different fissures. A major contour change occurred around Fissure 22, where the earth is now 180 feet taller than it was prior to the eruption, per the USGS. Lava flows at Fissure 8, the most active fissure of the eruption, produced a cone that rises up to 167 feet.

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Wide angle photo showing the Fissure 8 cone as things were cooling off in October 2018.
Image: USGS

Janet Babb, a geologist with the USGS Hawaii Volcano Observatory, said scientists developed this new map largely through aerial surveys, including the unprecedented use of drones during the eruption. Now that the eruption is over, the USGS is continuing to refine its measurements and fill in the gaps by sending researchers out into the field.

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While it hopes to have a completed version within the next year, the wealth of data the eruption produced will keep scientists busy much longer.

“This lava flow is going to be the site of study for years to come,” Babb told Earther. “Anything we learn helps us with future eruptions.”

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