As Mauna Loa erupts, lava flows toward a key Hawaii road. Can authorities stop it?

Slowly, slowly, the lava oozing from Mauna Loa is headed toward one of the main roads on the island of Hawaii, and with it comes renewed questions about whether the flows can be diverted or stopped.

Short answer: Not really. And authorities are particularly reluctant to even try because many Native Hawaiians believe disrupting the lava is disrespectful to the volcano goddess Pele.

“It comes up every time there’s an eruption and there’s lava heading towards habited areas or highways. Some people say 'Build a wall' or 'Board up' and other people say, 'No don't!,'" said Scott Rowland, a geologist at the University of Hawaii.

Around the Big Island, signs of past lava flows are inescapable, including along Saddle Road — a key route on the island also known as Daniel K. Inouye Highway or Highway 200 — that's now being threatened. The road runs between the summits of Mauna Loa and Mauna Kea.

Many people understand lava from its depiction in movies: flowing rapidly downhill like water. And that can be true in some cases.

Right now, the kind of lava flowing is "kind of like a bulldozer," said Wendy Stovall, a U.S. Geological Survey volcanologist. "If an eruption continues and lava continues to flow, it can overtop anything in its path."

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Hawaii typically sees two different kinds of lava flows: Smooth, shiny flows known as pāhoehoe and a more rough, clinker-like kind called ‘A‘ā. The ‘A‘ā type of lava can move faster than pāhoehoe, laying down a bed of cinders and then flowing atop them. Listening to that kind of flow sounds a lot like Styrofoam being crumpled.

Stovall said the biggest factor in whether lava will flow over or destroy roads and structures is the length of the eruption: If the lava keeps coming, it will ultimately pave everything in its path.

But the reality is even when flowing, lava rarely moves faster than a brisk walk.

Authorities in Hawaii have occasionally tried to divert flows, both with walls and explosives. Neither worked particularly well.

“Most people’s orientation on this kind of thing comes from movies. It’s a common enough trope in movies that we forget how unrealistic that is," Shannon Kobs Nawotniak, an Idaho State University geosciences professor told USA TODAY during the 2018 Kilauea eruption on Hawaii, which destroyed more than 700 homes. "You’re not going to sink into it like Gollum in Lord of the Rings. It’s really not like that. It’s slow-moving and inexorable and strong, but it’s not going to suck things down.”

Across the globe, the highest-profile time authorities successful diverted a lava flow was for a slow-moving flow threatening the sole harbor on a tiny Icelandic fishing island. For five months in 1973, workers doused the front of the flow with ice-cold seawater until it ground to a halt. That required 1.5 billion gallons of water, and the lava still destroyed hundreds of homes.

In 1990, a lava flow from nearby Kilauea volcano destroyed most of the town of Kalapana, and in 2018 more Kilauea flows destroyed dozens of houses in the Leilani Estates neighborhood. Those 2018 flows also covered several roads with more than 20 feet of lava, which has still not been removed.

"It's heartbreaking to watch the residents deal with it, (but) I think they know and understand that Madam Pele decides who will be impacted," Hawaii Gov. David Ig told USA TODAY during the 2018 Kilauea eruption.

Contributing: The Associated Press

This article originally appeared on USA TODAY: Lava is flowing toward a key Hawaii road. Can authorities stop it?