At the timing of the earthquake, some signal detected in both accelerometers and microphones(transfer the vibration to microphone itself.)
I compared the behavior before and after the earthquake, the effect of the LSC lock would be large.
One big different is GND voltage monitors as shown in Fig.1.
(Blue) before the earthquake, LSC_LOCK = OBSERVATION, 2023/05/04 08:00:00
(Red) after the earthquake, LSC_LOCK = DOWN, 2023/05/05 08:00:00
PSL, IMCREFL, REFL, ISS table : larger in lower frequency, several peaks disappeared, but no large difference appeared.
AS table , OMC chamber : many peaks disappeared.
I don't know why so large difference detected in AS table and OMC chamber.
Not only the interferometer, but also suspension state would be SAFE, No IMC.
(After the recovery of suspension and IMC, the spectrum of AS table and OMC chamber is so quiet, so interferometer status is affect to the spectrum?)
Interesting data!
I am interested in the time trend data around the first M6.3 earthquakes(including from ~1 min data before and after the erathquake). If some specific frequency noise and/or the rms floor level were suddenly/gradually decreasing or not?
In addition, some of the suspensions were manually set to safe mode. So, the relation btw spectrum/time-series data and some kind of actions/IFO status are interesting.
Actually after changing the suspension state, RMS of GND volt monitor changed(RMS also changed in early morning).
But largest change was happened after ~20min from 1st earthquake.
Now I am searching the reason.
No change around OMC PDs.
One possibility is commissioners change the Type-A suspensions from TRIPPED state to SAFE state.
(Blue) soon after the earthquake 23/05/05 08:00:00(UTC)
(Red) Today with PRFPMI lock (WFS alignment) 04:00:00(UTC)
Several peak newly appeared, the spectrum of the OMC chamber is significantly great.
(Earthquake cleaned up the dirty GND(?))
We will wait the silent run.
