How many monuments do you find moving?
I've got some areas where the movement is substantial. One C1/4 moves about 8" every ten years to the SE. A township brass cap moves SW about 1' per decade. Yesterday the PC located 15 monuments from a prior 2005 survey and three of them have moved, averaging about .15'. These are easy to spot; concrete ROW monuments leaning along the fill side of a highway.?ÿ
GPS has made it much better to track some of the areas with movement. We saw it during instrument surveying also.?ÿ
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In 2018 we had a 7.1 earth quake that shook things pretty good. Most areas did fairly well but homes built on fill suffered the most. Since then I've identified several areas where the ground over a fairly wide area shifted up to a foot, mostly in wetter areas closer to rivers that are mostly made up of glacial sediments.
Just because I'm paranoid, doesn't mean they aren't out to get me.
I set a corner post for a fence in the Fall of 1983 that has only moved whatever the tectonic plate has moved. A large portable air compressor was used to power a jackhammer with a 2-1/2" bit to honeycomb solid bedrock to a depth of two feet. Then a sledge, chisel and bar were employed to break out the honeycombing to leave a hole large enough for the hedge post to be inserted and quikrete poured in the narrow gap between the post and solid limestone.
I did a survey on a bend in the Ohio River with traditional methods and came back about 8 years later and there was up to 6' of movement amongst a dozen pins that had been set very precisely. The hill was sliding into the river and not all at once