I’ve seen this phenomenon many times over the years, while walking the dog out behind our house. The cables wiggle between these two particular power poles, but NOT between the adjacent poles (or any others, along this pole line). There is no wind, no earthquakes, no herds of animals or large vehicles/machinery anywhere nearby...
This doesn’t fit the format, and can’t work with it, but this is where my head went as soon as I saw “11 Rikers Riking” -First truly “high effort” post on my part - this took more time than I care to admit.