What caused the raised asphalt on Highway 101 near Hollister?

HOLLISTER, Calif. (KION-TV)- The number two and three lanes of southbound Highway 101 north of State Route 156 were closed Tuesday for immediate repairs to fix a section of raised asphalt, said the California Highway Patrol.

Public Information Officer for Caltrans Alexa Bertola stated that “The pavement buckled in the number two and three lanes early this morning.”

This kind of report is the first of the year according to Cal-Trans, however, this isn’t a rare issue across the country. 

According to Accuweather.com, seven other states have reported buckling pavements in the past six years. The common factor for these incidents is the summer heat.

“At this point, we don’t know for sure, but it seems likely that it is extreme temperature related.,” Bertola said. “That means expanding pavement, and eventually, it had nowhere to expand.”

Although Caltrans says heat might be a factor -- where this happened, some at the USGS, like Research Geologist Belle Philibosian, think there might be another reason for the buckling.

The fault's movement may appear small, but the road work needed to repair it says otherwise.

“Certainly, the heat is a factor,” Philibosian said. “But it’s probably not a coincidence that that occurred right on top of the San Andreas Fault.”

Philibosian echoed this, stating, “There’s still some creeping that’s going on under the 101 Freeway there and with the position of the fault there, over time, has probably weakened the pavement.” 

No matter the cause, Caltrans looks to get the roads repaired soon. As of 7 p.m., the number two and three lanes have been reopened.

Caltrans says the number one and two lanes will be closed Wednesday from 6:30 a.m to 5 p.m. for additional repairs.