corey.gray@LIGO.ORG - posted 03:58, Friday 03 May 2019 (48957)
Took SEI_CONF to EARTHQUAKE State & Rode Thru 6.1 EQ in South Pacific (near Solomon Islands) + Wildlife
Summary: Below is a rough summary of how things went down for H1 to ride it through an earthquake. The notification came just as Jim was leaving so we discussed scenarios before he left. (I was also distracted by a pair of coyotes on our cameras.)
Attached are screenshots of various tools to show a narrative of EQ tonight.
EQ Log:
- 6.1 magnitude EQ near Buala, Solomon Islands occurs locally at 7:25utc (USGS website)
- 7:30: Get first "incoming EQ from solomon islands" Verbal Alarm (get another at 7:41)
- Jim & I pow wow about what to do. Basically:
- Watch all signals/tools we have, if we see noticeable activity, safest action is to engage SEI_CONF's EARTHQUAKE STATE. After his recent work he has reduced useismic noise with filters to make it easier for H1 to handle this state...but we also have low useism.
- If ASC signals get huge and/or ADS lines get buried in DARM spectra noisefloor, take ISC_LOCK to EARTHQUAKE state.
- NOTE: Changing SEI_CONF to EQ state will NOT take us out of OBSERVING, but taking ISC_LOCK will take us out of OBSERVING)
- 7:49: See ASC signals get noisier, as well as:
- tidal signals (nuc1)
- CPS signal (red trace on SEI_CONF's strip tool)
- 7:50 Transitioned SEI_CONF to EARTHQUAKE state
- ADS lines look fine on DARM & ASC Strip tool begins to look better.
- 8:09-9:30 Wildlife note: Distracted by pair of coyotes on camera around OSB parking lot & eventually go toward wood shop. Also saw two different porcupines.
- 8:19 Big R-Wave observed on-site
- 0.03-0.1 blrms seismic FOM peaks at about 2 um/s
- Peakmon ndscope reaches 3400 (vs normal 200).
- All 3 ifos still locked
- 8:23 L1 lockloss
- 8:28 Begin to notice big low-frequency (i.e. 0.003Hz) waves (i.e.6-7min period) on tidal strip tool and CPS striptool
- 9:17 0.03-0.1 blrms seismic FOM down to about 0.1um/s. Decide to hold here a little longer....there has been NO drop in range for H1 while in EARTHQUAKE state, so no rush to return. Besides, still see the multi-minute period waves on ASC...in other words, Earth still shaking.
- 9:50-9:52 Transition back to WINDY state (on SEI_CONF)
- 9:50 0.003Hz seismic wave finally subsides
- 10:18 L1 back to OBSERVING
Images attached to this report
