Mauna Loa erupts, after several years of warning activity, and sends lava rolling slowly down its slope.

Despite being known as the world’s largest active volcano, Mauna Loa, the central peak of Hawaii’s Big Island is currently erupting for the first time in nearly 40 years. Late Sunday night, three fissures opened on the northeast flank of the volcano, spitting lava fountains almost 140 feet into the sky. There were initial fears that the flowing lava could head towards South Kona, a populous area of the island, but currently it’s only flowing towards unoccupied land.

Monday night, lava did cross the access road to the Mauna Loa Observatory and cut off power to the facility, but no one was endangered by the damage. Currently, the only area of concern in the lava’s path is Saddle Road, also known as Daniel K. Inouye Highway. The lava is still over 3 miles from the highway and moving slowly, but officials are concerned that it could close the only good road that connects the two sides of the mountainous island. In two or three days when it finally gets there.

The advancing flows “are approaching a relatively flat area and will begin to slow down, spread out, and inflate,” according to a statement by the U.S. Geological Service, who is monitoring the event closely.

Tourists at the Hawai’i Volcanoes National Park about 20 miles away can see two simultaneous eruptions from the park’s viewpoints: Mauna Loa’s lava fountains are visible in the distance, while much closer Kilauea’s lava lake casts a brilliant glow into the haze of steam and gas.

While the lava is days or weeks away from being a threat to anyone, there are more urgent concerns. Volcanic gases, fine ash, and airborne volcanic glass (Pele’s Hair) can be carried downwind, making outdoor activity risky to those with respiratory sensitivities. Officials warn against panic, but say to be careful.

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