Page is 49 miles farther away from Flagstaff today by road after a 150-foot-long section of Highway 89 collapsed Wednesday at a place called the Big Cut, about 25 miles south of Page.
No repair date has been set.
The road surface appears to have split in multiple places and is divided by one fissure greater than 5 feet deep.
Three accidents resulted from drivers hitting the large drop-off, with the most serious involving a driver whose airbag deployed. She was transported to Page with minor injuries, according to state law enforcement officials.
Page Unified School District is using a bypass road on the Navajo Nation to get students home about 45 minutes to one hour later than normal today. It plans to change its pickup and dropoff times until the road is repaired.
Highway 89 is closed northbound at the 89A turnoff to Marble Canyon and southbound at the State Route 98 turnoff in Page.
Highway 160 out of Tuba City and SR98 are recommended as the alternative route, adding about 49 miles to the trip between Page and Flagstaff.
While the school district is using dirt roads, a deputy with the Coconino County Sheriff's Office is recommending drivers use those paved roads recommended by ADOT.
He cautioned the dirt and sand roads were "drive-at-your-own-risk" and affected by varying weather.
The president of the Coppermine Chapter asked the public to avoid Coppermine Road (a dirt and sand road sometimes declared paved by travelers' GPS units), and he said Navajo Nation police were blocking most nonlocal traffic into it.
"It gets muddy if it snows or rains," Floyd Stevens said. "Sometimes it becomes impassable."
A tour bus became stuck on the road in the summer of 2012.
ADOT did not know when the collapsed roadway might be repaired.
"We do know that it's not going to be a short-term closure. This is significant damage and it's going to require significant repair work," said Tim Tait, ADOT spokesman.
ADOT isn't sure yet what happened, he said.
"It's really too early to speculate. We have geotechnical engineers that are en route to the scene. They'll be able to place some monitors and get a sense of what's happening," Tait said.
No significant seismic activity was reported south of Page on Wednesday morning, said David Brumbaugh of the Arizona Earthquake Information Center at Northern Arizona University.
Wal-Mart and Safeway reported they were bringing supplies in via other routes and didn't expect problems.
Colorado River Discovery takes tourists down the Colorado River from Glen Canyon Dam to Lees Ferry starting in March, then back up Highway 89 by bus. Now, they would have to drive south to Tuba City and take the detour if they choose to use the bus.
"We're probably the most affected amidst this closure," said Cory Seyler, general manager of personnel.
Flying passengers from Marble Canyon to Lees Ferry could be an option, along with doing two-way boat trips on the river (using motors to power up it and down it).
"We have comprehensive plans in order to continue to run these trips and not inconvenience passengers," Seyler said.
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Highway built atop old landslide
The area 25 miles south of Page wasn't shaken Wednesday by record-setting floods, earthquakes or an asteroid.
Rather, parts of Highway 89 likely came apart because the road was built on an area that had previous landslides, several geologists at Northern Arizona University estimated in reviewing photos of the road damage.
"... it looks like that whole section of road is on a big landslide," said Joe Hazel, a researcher in NAU's geology department, along with colleagues.
In addition to being on a slope, the kind of rock and clay on which that part of the highway is built also particularly unstable.
To put it into perspective, think about the same highway closer to Cameron, said Rod Parnell, NAU professor in earth sciences and environmental sustainability.
The road there dips and rises often -- evidence of it being built on the Chinle Formation, a layer of earth full of a clay that's packed with an mineral called smectite.
Smectite expands when it gets wet with rain or snow, Parnell explained.
It shrinks when it dries.
So it's sort of like building a highway on a sponge -- that hard asphalt is bound to crack as the ground beneath it shrinks and swells, and it often does so on Highway 89 near Cameron.
The segment of Highway 89 that fissured here was a little higher up in elevation and geology than that near Cameron -- sort of like a layer of rocks piled on that clay sponge, with an asphalt road on top.
Geologists around Arizona used Google Earth on Wednesday to check out the area.
They found an old landslide above and below the freeway.
"People build roads on old landslides all the time because they're the easiest way to get up mountains and canyons and such," Parnell said.
The upper landslide area might have channeled water into a few points of the road, Parnell said.
One option could be to route any water away from the road, Parnell said.
"Once it's failed once," he said, "it's easier for it to fail again."
-- Cyndy Cole, Daily Sun staff
This report has been edited from its original version.