Fault gauge, 39th Avenue

South of the LDS Temple, the Hayward fault runs down a well-defined gulch, past the stream offset at Rettig canyon, and becomes more subtle as it traverses Redwood Heights. It’s mapped going down Jordan Road and then Victor Avenue. Here’s where Victor butts against 39th Avenue.

It only takes a moment with a concrete saw to set an unobtrusive fiduciary mark like this. It will document offset along the fault, whether it’s aseismic creep or a more massive wrench when the fault lets loose.

[I revisited in 2013 and 2018]

One Response to “Fault gauge, 39th Avenue”

  1. Christoph Says:

    What an easy and effective way! Great idea. Do you know about the rate of creep there? Offset seems to be in the order of 1-2 cm, how old is the mark?

    [I don’t know how old the sawcut is, but the US Geological Survey records show the fault zone as moving at 4.2 millimeters per year since 1974, measured along a 137-meter line across the fault. Across Oakland, creep seems to range from approximately 3 to 5 mm/yr. — Andrew]

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