The leading edge of the Mauna Loa lava flow slowed to a crawl Thursday as it worked its way over the relatively level terrain of Hawaii island’s saddle region.

With the lava moving at a rate of 30 to 40 yards per hour, scientists are now estimating that it won’t reach Daniel K. Inouye Highway, also known as Saddle Road, for at least a week.

That doesn’t mean lava production has slacked off. Rather, it’s a reflection of the flat terrain, according to Ken Hon, scientist-­in-charge at the Hawaiian Volcano Observatory.

The eruption continues unabated in its fourth day with two active fissures feeding lava flows downslope.

Fissure 3 remains the dominant source of the largest flow and the source of the leading edge, situated near the 7,000-foot level, 3.2 miles from the highway as of 1 p.m. That’s progress of about two-tenths of a mile over the previous 24 hours.

Hon said he expects the flow’s movement to become sporadic as it edges its way across the relatively flat ground.

“It will inflate. Incoming lava will be stored in it, and then it will probably come out in lobes at different times. At some times it will appear to be moving faster, and other times it will not be moving at all,” he said.

The flow, he said, is in a region with a divide that could take the lava in different directions — either to the east side of the island or the west side.

With so many variables at play, both the direction and timing of the flow’s advance are fluid and expected to change over periods of hours to days, according to the Hawaiian Volcano Observatory’s latest update.

“We don’t really know which way the lava flow will ultimately go,” Hon said. “There’s a lot of uncertainty here.”

Fissure 4 is the other active vent on the mountain, producing flows moving toward the northeast, although a small lobe that was going east stalled.

HVO scientists said their seismic-­monitoring equipment continues to detect plenty of earthquakes near the active fissures. That means magma is still coming up, and the eruption will keep going as long those quakes continue.

Plumes of volcanic gas were lofting high into the atmosphere Thursday afternoon, and there were earlier reports of Pele’s hair — volcanic glass segments — blown 15 miles downwind.

Elsewhere Thursday, officials announced the opening of a new viewing area designed to take the pressure off busy Saddle Road, which has been even more swamped with traffic and volcano watchers and is creating hazardous conditions.

Hawaii County Mayor Mitch Roth said the new “traffic hazard mitigation route” uses the old Saddle Road with the entrance located directly across from the Gilbert Kahele Recreation Area. The one-way route is 4.5 miles from the entryway to a junction point just before Puu Huluhulu, which is across from the highway’s intersection with Mauna Kea Access Road.

Passenger vehicles are allowed, but commercial vehicles are prohibited from entering. Signs and barricades will be present, while safety officers help to direct traffic flow.

Parking will be allowed only on the right side, but vehicles cannot stay in the area more than 90 minutes, officials said.

“We are humbled to have come together with our state and federal partners to find a potential solution to the ongoing safety concerns along Saddle Road,” Roth said in a statement. “Our teams have worked tirelessly to keep the community safe through this eruption, and through the creation of the traffic hazard mitigation route, we believe that there will be significantly less risk to our community.”

Motorists are asked to drive with extreme caution given the roadway will be busy during the eruption.

The Gilbert Kahele Recreational Area, including both the lower and upper bathrooms, will be open 24 hours each day until further notice, officials said, and security guards will be on-site nightly from 6:15 p.m. to 6:15 a.m.

Another place to view lava is at Hawai‘i Volcanoes National Park, where one can see both the eruption from Kilauea and a night glow from Mauna Loa. It’s the first time both volcanoes are going off at the same time since 1984.

The park has launched a new eruption viewing page on its website — bit.ly/ 3B70dtB — which provides recommendations for safe watching.