Last night, the microseism went up to ~1 um/s and we had trouble locking. This continued all day today. I redid some DRMI alignment (very small adjustments) and Sheila and I switched the SEI FF state a bit, and now things are locking well. WE have gotten to low noise many times tonight.

I was curious about what counts as 'high useism'. This plot (https://ldas-jobs.ligo.caltech.edu/~detchar/summary/day/20181027/sei/ground_blrms/) compares the BLRMS at the 2 sites. As you can see, LLO has no serious problems with ~1 um/s.

Reading many entries, there are several times in the LHO log over the past few years where people not how the locking is really poor when the useism is at 1-2 um/s. Sometimes this also includes wind.

It would be useful if someone in DetChar could crawl through the locking records over the past few years to find out how touch locking is as a function of seismicity. So that in addition to the word of mouth guidance, we also have a some kind of DHS threat level that incorporates ground, wind, etc.