BOISE, Idaho — Idaho Transportation Department maintenance and bridge crews are cleaning up debris and inspecting infrastructure after a 6.5 magnitude earthquake shook the Idaho Central Mountains Tuesday night.
Several mountain highways saw rockfall on the roadway following the quake. That includes Idaho Highway 75 near Stanley, Highway 21 north and south of Lowman (pictured), Highway 55 between Horseshoe Bend and Cascade, and Highway 52 east of Emmett. “Maintenance crews were immediately deployed to clear these hazards from the roadway and ensure the road was safe for travel,” said ITD spokesman Jake Melder.
Aftershocks continue to rock the region, causing additional rockfall. “Crews are patrolling these high-risk areas to actively clean rocks from the highway. ITD urges the traveling public to use caution when driving in these areas,” Melder said.
After the earthquake, maintenance crews scanned bridge structures for damage. “At this time, there has been no damage of concern noted and the highways remain open. As is always the case, if any issue is spotted, ITD will immediately close a bridge,” he stated.
ITD’s Bridge Department is conducting more detailed analysis of the situation. They are conducting additional analysis of structures closer to the earthquake’s epicenter. Over the next several weeks, inspections will be conducted on priority structures to determine whether damage has been done and repairs are needed.
A storm system dumped 27 inches of snow in the Canyon Creek section of Idaho Highway 21, from Grandjean to Banner Summit. This increased the risk of avalanches, so ITD closed the highway at 2:00 p.m. Tuesday, several hours before the earthquake.
The earthquake did cause several slides to fall onto the highway in this area. “Crews entered the area to begin clean-up Tuesday night and quickly found the landslides were extensive. The crew contacted the U.S. Geological Survey, which informed them of aftershocks and the risk of additional landslides. The crew withdrew -- and will remain out of the canyon until USGS has determined the risk of aftershocks is reduced,” Melder explained.
“At this time, the number and extent of landslides on this section are unknown. There is no timeframe when crews can re-enter the Canyon and begin clearing the road. Additional repairs to the roadway may be required as well. The Department is advising it may be many days before this section of ID-21 re-opens. Idaho Highway 75 and U.S. 93 remain open to access Stanley,” he added.
(photo courtesy: ITD)