This anon has been following lines of earthquakes until he finds one at zero depth, and then zooming in.
Almost always find an area with pinkish coloring stained on the ground.
Then I found this one. Erosion has exposed the tunnel, and there's the pink too.
Requesting other anons chek this with earthquake apps, I have 5 solid entrance locations already.
This one looks like it failed too. Note the curvature of the tunnel wall, and again pink stained ground.
A line of quakes led to a surface jolt at this mine, right in Butte, MT.
Note the pink staining.