A LANDSLIDE: THERE ONE DAY AND GONE SOON AFTERWARD

HERE ONE DAY, GONE SOON AFTERWARD

Southern California has its share of mountains and hills with sedimentary beds that have been tilted to considerable steepness by ancient and on-going tectonic uplifts and earthquakes. Under the right conditions, namely, already strongly tilted layers and soft sedimentary layers (e.g., muddy siltstone), slopes will fail and landslides are inevitable.  

In late November, 2015, one of the local county roads (Vasquez Canyon Road) was suddenly and strongly warped by a landslide (about 150 feet across) that was relatively small, but,  nevertheless, very destructive. Tons of tilted sedimentary beds of poorly cemented mudstone abruptly shifted downhill. Numerous crevasses formed on the hillside. Some of these cracks were up to 20 feet deep and 10 feet wide. The adjacent was highway was tilted every which way!

The pictures below show various views, in temporal sequence, of the landslide block. The road had to be closed for many months while construction crews removed tons of highly damaged road and, in so doing, eventually stabilized the slope next to it. Notice on the left side of the first image below, the steep, over-turned (concave/bending) fold. The sedimentary layers were already at a steep angle, and were eventually primed to fail. The first images show how the slope and the adjacent highway "took a beating." The last two images show what the area looked like, many months later.

Before the area was cordoned off to the public, people came to skate- board down the irregular slope that was once a relatively smooth, non-undulating highway.

Several months later, after the slide area was deemed to be stabilized.

This last image was taken after the road crews were finally done with the removal of a large portion of the remaining slide. It took many months!