Last night during one of the lock stretches there was an small earthquake. It wasn't big enough to break the lock, but it was big enough to show up in a number of channels in the IFO.  During the earthquake last night, no change was made to the seismic configuration, so it makes for a good comparison with the "earthquake" configuration from my alog on June 29, 28050. The first two plots are the minute trends of RMS 30-100mhz Z LVEA and ETMX  motion (best I could do for both days) for the 10minutes of data I'm comparing between the two earthquakes.  Keep in mind the that RMS motion in this band is higher for the June 28 earthquake, than last night.

The next plot shows a version of DARM for 3 different times, red is June 28, green is last night's earthquake and pink is 10 minutes of quiet time before last night's earthquake. You could be forgiven for looking at this plot and wondering why we don't run the earthguake configuration all the time. The current "windy" configuration should do better during high microseism, where from O1 we know we need inertial isolation in the .1-.3hz band, which the earthquake configuration won't provide. The next plot shows IMC-F, which is a measure of CARM (the units aren't really calibrated, just scaled to be similar to the other spectra), the  color scheme remains the same, red is June 28, green is last night's earthquake and pink is 10 minutes of quiet time before last night's earthquake. CARM (IMC-F)  and DARM are both lower for the bigger June earthquake (where we used the seismic earthquake configuration) than for the smaller earthquake last night. I think this shows that for low microseism, we want to use this configuration. More thought will be required for a winter configuration, but suppressing the microseism while staying locked to the ground below 100mhz will be hard.

We are working with MIT to get SEISMON/Terramon transplanted here, so we can get more reliable earthquake warnings. RIght now the earliest, and most reliable warning we get comes from watching IMC and STS time series on the wall FOMs.