Hawai‘i Volcanoes National Park’s Thurston Lava Tube will open to the public this morning for the first time since it was knocked out of action by the Kilauea eruption nearly two years ago.

“We are overjoyed that we can again welcome visitors back to Nahuku,” acting park Superintendent Rhonda Loh said, using the Hawaiian name of the 400-foot lava tube.

The popular walk-through attraction was closed May 4, 2018, following a 6.9 magnitude earthquake and four months of volcanic and seismic activity, including the collapse of the Kilauea summit crater, that dislodged several large rocks from the lava tube’s ceiling and caused new cracks to appear.

A National Park Service geomorphologist, mining engineer and other specialists surveyed Nahuku and determined it could be reopened if certain safety measures were addressed, said Ben Hayes, the park’s chief of interpretation.

Two crack monitors were installed, he said, and reflectors were installed to mark off a low-hanging rock to prevent head injuries. Drainage was improved to reduce standing water on the cave’s floor, and the electrical line to a bathroom was replaced.

As it was before the eruption, the lava tube will be open 24 hours a day but will be lit only from 8 a.m. to 8 p.m. Visitors are advised to bring a flashlight and extra batteries if visiting before 8 a.m. or after 8 p.m.

During the long closure, roots from the ohia trees that grow on top of the lava tube grew down through the ceiling to reach the floor in some areas, a likely result of the absence of people for so long.

Also new are large colonies of white microbial matter on the lava tube walls that grew during the extended periods of darkness and natural light.

“It’s really cool,” Hayes said of the microbial matter. “It shines bright and vibrant under a flashlight.”

An eruption from Kilauea between 1420 and 1470 produced strong streams of lava, and the long, hollow tunnel was left behind when the molten rock drained away.

The lava tube was discovered in 1913 by Lorrin A. Thurston, publisher of the Pacific Commercial Advertiser, a forerunner of what today is the Honolulu Star-Advertiser.

Thurston used his newspaper to promote the creation of the national park and convinced the territorial Legislature to fund a group of congressmen to visit Haleakala and Kilauea in 1907. Thurston led the tour, and the park was established in 1916.

The lava tube’s Hawaiian name, Nahuku, means “the protuberances,” which possibly refers to the lava stalactites that once covered the tube’s ceiling. Those, however, disappeared due to souvenir collectors, officials said.

Today more than 2 million people visit the park annually, and the Nahuku lava tube is one of the top three attractions in the park, Hayes said.

Lights were first placed in the lava tube in 1959, and a new electrical system with energy-efficient amber LED lights was installed in early 2018 — two months before Kilauea came alive and the park was rocked by some 60,000 earthquakes between April 30 and Aug. 4.

In addition to the pain felt at Hawai‘i Volcanoes National Park, lava spilled into the lush Lower Puna landscape, covering 13.7 square miles, destroying 716 homes, isolating 1,600 acres of farmland and causing more than $800 million in damage.

At the park, the crippled Jagger Museum is expected to remain closed, with its functions eventually offered elsewhere within the park. Another mile and a half of Crater Rim Drive is expected to be reopened to Kilauea Overlook in the coming months. And additional sections of trails damaged and undermined by the eruption also are planned to be reopened.

Officials said the Federal Highway Administration inspected park roads after the eruption and determined the parking lot at Thurston Lava Tube was unsafe. As a result, the stalls perpendicular to Crater Rim Drive were eliminated.

There are now 14 stalls parallel to Crater Rim Drive, two accessible stalls and two stalls for commercial tour vans. Parking is limited to 30 minutes, and there is a new passenger loading and unloading area. Visitors also can park at alternate sites, including Devastation Trail and Kilauea Iki Overlook.

“We appreciate the public’s understanding and support during this long road to recovery following the intense volcanic activity of 2018, and urge everyone to be mindful of potential risks when entering any lava tube,” Loh said.