Southern California Regional Rocks and Roads - Ridgecrest Earthquakes of July 4-5, 2019

*Map of the area. Section A covers the fault rupture. Section B covers the rockfalls in Poison Canyon. Section C covers the ridge shatter visible along State 178.*

After leaving the fault rupture, it was time to head down to Trona. I was told by a couple of the engineers at my office (Division of the State Architect) that I should check out some of the damage at Trona High School. The first thing we noticed was the sidewalk out front. Many of the panels had been shifted quite a bit and the curb had even overturned. The ground surrounding the sidewalk and buildings was also fractured somewhat heavily in places.

In front of the school, looking south along the main sidewalk.

The buckling and shifting is a lot more apparent here.

Gaps between the slabs and somewhat fresh asphalt in the parking lot are quite large here.

Fracturing and buckling in the ground from the shifting of the sidewalk slabs.

Partially overturned curbing. Ground movements were quite severe here.

Small cracks around the edge of the Administration building. Many of the structures had these surrounding them.

Not just sidewalks were damaged at the school, however. Our engineers “yellow tagged” the gymnasium and a couple other structures due to some partial facade and wall failures. By the time I got there, some work had been done to remove some of the damaged portions.

A brick facade at the gymnasium, which was starting to peel away from the structure, was located where the exposed wood is in the photo. Yellow tag on the door is from our engineers.

Some repairs and investigative work on some of the classroom buildings at the school are visible in the background.

After leaving the high school, we went just a bit north to the Inyo county line. If nothing else, just to add another county to the trip. When we got there, we found there were still more fractures in the ground from the earthquake.

Heading south back through town, we found a few structures that were heavily damaged by the shaking. These buildings were classic examples of why reinforcing material is necessary in masonry structures. Unreinforced masonry is essentially just a big pile of bricks just waiting to topple over.

South of Trona, we made a couple of stops in Poison Canyon. This area was the site of many rockfalls which partially blocked State 178 the day of the earthquake. One of the things I noticed quite readily was how the surface of the low hills, which had a sort of crust on them, was shattered and had fallen down. The crust itself was created by expansive clays within the lacrustine deposits below.

Slope adjacent to State 178 with a shattered crust.

Bits of the crust creating a sort of scree slope at the base.

Further along in the canyon, it was all about the rockfalls. Some of these damaged a water pipeline that feeds into Trona, which took a while to get repaired.