Johnson Canyon Fault Zone


Can you see the fault in this photo?

One of the interesting things that I have learned about our home in Johnson Canyon is that we live almost directly on top of an active fault zone. While there have not been any detectable earthquakes in the 5 years we have been here, there is always the chance that one will happen. As soon as I heard about the Johnson Canyon Fault Zone, I began researching, and trying to find signs of the faults. At first, I did not see them, until my mind adjusted for what I was seeing. I am used to looking at faults from the side, where you can easily see both sides of the fault, as with the photo below.

In the photo above, it is easy to see that one side has moved down relative to the other side.

Here, I had to realign my thinking to see the fault from one side. Compare the first photo with the photo below. The red arrows point to the same layer of dark red, resistant rock. Notice that the layer is lower on the left and right, and higher in the middle. The fault is parallel to the middle cliff face, with the side towards us moving down relative to the side away from us.

Now try looking at another photo, to see if you can spot the fault.

Do you see it? Look for that same layer of dark red, resistant rock. Then compare your answer with the photo below.

Looking on a geologic map, you can see the faults as black lines (faults) and dotted lines (where we think the fault is). I have marked the locations where I took the photos. The top photo is Photo 1.

I even managed to find some slickensides, a German word for the structures formed when the two sides of a fault moved past each other. It metamorphoses the sandstone, leaving grooved quartz that indicates the direction the fault moved. In this case, the side towards the camera moved down relative to the side which has the slickensides.

I keep watching the local seismograph page (https://www.earthquaketrack.com/r/utah/recent) to see if any activity shows up. Nothing so far, but I will be sure to post if a quake happens here.

You can learn more about faults in my Faults video.