We have now had a couple lock losses (at least 1 yesterday, 2 today) due to ~30sec bursts of loud 1-10hz ground motion. This is probably the same thing Tony saw yesterday, that I commented on. These seem to be loudest at EY, which is a little bit closer to the 10-240 intersection than the corner station, so probably it related IS to work on the Highway 240 round-about construction, contrary to my comment yesterday. From google maps, the intersection is 3.7 miles from EY, 5 miles from the corner station. Attached trends show different ground timeseries during the most recent event at about 17:20 utc.

Top two plots are the X and Y ground STS, ITMY X and ETMX X on the left, ITMY Y and ETMY Y on the right. Middle left is Z motion for all 3.

Middle right plot is the 1-3hz blrms for all three STS. The largest motion is at ETMY , ~2x larger than the other for this band.

Lower right is the 3-10hz blrms. Again, loudest at EY, I think these colors aren't great, but all stations see ~10x more motion.

Lower left is a few channels outside of 1-10hz. ITMY doesn't seem to see anything above 10hz. ETMY and ITMY both see 10x in the .3-1hz band. ITMY doesn't see anything in the .1-3hz band. This is all consistent with my spectra from last night, with increased motion .5-10 hz.

I don't know what we can do to prevent this. A 10x increase in motion at these frequencies isn't going to break anything, we aren't tripping watchdogs. But our run time won't be great if this keeps up.