Mapping Magnetic Fields

A couple of months ago, I posted a pair of pieces on an aerial geophysical survey intended to clarify seismic risks in southern Washington and northern Oregon, News You Can't Use and USGS Aerial Magnetic Survey. A resident of Boardman, OR, which is where I-84 turns off to the ESE and away from the Columbia River, just sent me a photo, apparently of one of the survey planes still at work. In the original press release, the survey was expected to be done during July. I guess it's taking longer than anticipated. Thanks for the photo, JMD!The first time I heard of the OWL was on a field trip in and around the Snake River Canyon with Tracy Vallier- I'm guessing that was about 1987. Just below one of the dams, there was a fault that he thought might be associated with that enigmatic structure. I just realized a moment ago, looking over the second post linked above, that the idea of the OWL being an optical illusion might not have been very clear. Essentially the question is, is there an actual large-scale structure that has created the various associated landforms and structures, or is it a bunch of smaller landforms and structures that just happened to be lined up with each other? Either way, it has important implications for the seismic risk in the region.