So I checked the seismometers signal.
1. The amplitude seems EXV >> IXV >>>> EYV (Fig.1.)
Clear signal in EXV, some signal in IXV and no signal in EYV.
2. Expand to this morning (Fig.2.)
The behavior of IXV and EXV is different(?)
Maybe, the ground motion at EXV (All direction) would be a daytime ground motion.
3. Spectrum (Fig.3.)
I compared the spectrum between 03:00:00(Blue) and 10:00:00(Red)
Significantly, there are excess in 2 - 20 Hz
4. Long term check
The amplitudes in each station(IXV,EXV,EYV) are daily dependence.
The first detection of this daily ground motion in 21st Mar., 2023. Only EYV seismometer detected (Fig.4.)
Sometimes, there are difference in finishing time for each station (Fig.5.)
I checked PEM-SEIS_{EYV,EXV}_GND_X_BLRMS_3Hz10 for 3 months from Nov/9 2022 to Feb/9 2023, for example.
The periodic changes that are higher-level on from Monday to Friday, mid-level on Saturday, and lower-level on Sunday in basic can be seen especially in EXV. Actually, low-level was kept around Jan/1 2023.
The fluctuation in EYV seems to be larger than in EXV although we don't know the actual calibrations. From the point of view of electrical facilities, the High-voltage from the Hokuriku-Power plant was delivered at the Mozumi entrance near EYV as SK and KAMLAND. So two possibilities to explain these weekly enhancements can be:
- The electrical load and related grounding condition changes of the power line from the Hokuriku Power plants itself caused some fluctuation and noises in data. In other words, these data is now polluted some grounding noise or something. However, this story cannot explain the "sharp" enhancement and suppression at precise times! Some activities of a company cause the electrical condition changes according to their working time?
- Some actual activities around the Mozumi entrance area cause seismic noise?
Do we have an electrical ground-level monitor?
This weekly enhancement seems to exist from when the data was started to be obtained from 2020 January.
Fig.1,2,3 correspond to the data for 19Nov-20Feb, 20Nov-21Feb, and 21Nov-22Feb. No data existed before 20Jan and there is a lack of data in 2020.
The daily level enhancement seemed to occur around April 19th 2022.
Fig1,2,3 correspond to 22Feb-22May, 22may-22Aug, and 22Aug-2022Nov.
A member of the Kamioka mine company explained that actually there have been activities in the tunnels around the Mozumi entrance side on water power plant construction. We need to know where (how far from EY, EX, CS), which tools are used, how many activities, and until when etc.
I made some plots of EYV X-direction (3-10Hz BLRMS) for each week.
The actual level enhancement seems to start in March and, and especially, almost week days enhancement can be seen from march 20th Week.
The data of the April 3th week is so characteristic.
3/24, 3/26, 4/30, (and 5/7 ?)are most likely dam discharging because the infrasound at Mozumi was also large.
To see the macroscopic situation clearly, I evaluated the seismometer RMS of the 5-time-bands for every day:
- 'morning': 0:00 ~ 8:00
- 'work_am': 8:30 ~ 12:00
- 'lunch': 12:00 ~ 13:00
- 'work_pm': 13:00 ~ 16:00
- 'night': 17:00 ~ 24:00
The first plot is for all days, and the second plot is for the days that non-working time is quiet (<0.004um/s)
On 15th May, We(Miyoki, Uchiyama, Yokozawa, Washimi) discussed with members of the Kamioka Mine company.
However, their activities seem unable to explain the detected daily seismic noise excitations. We need to find other possibilities.
I generated the same plots for the weeks after May 8.
The week from May 29 to June 4
I went to the Sakonishi-area and the road construction area near the Kamioka mine company office from 15:20~16:30.
No activities using heavy machinery around the Sakonishi area.
While there was excavator activity at the road construction area.
When I passed this area around 15:20, there was no activities of the excavator. After that, I went to the Sakonishi area, and there were no activities. After that, I went to the KAGRA entrance to get an internet connection and I monitored the ground motion, then I confirmed that the level denoted by green in the figure was low. After several decades of minutes, I noticed that the ground motion level was enhanced again. So, firstly I went to Sakonishi-area, but no activities. Then I went to the road construction area and found the excavator was working. I stayed near the SK entrance to obtain the EDUROM net to monitor the ground motion and the excavator activities. After the activity of the excavator was postponed, the ground level seemed to become low. Although I kept staying, the excavator did not restart its working until around 16:30. I gave up and went back to the KAGRA DAB. However, the figure showed one more enhancement of the ground just before 17:00. I should be patient :(.
I would like to go there and check again if there is the ground excitation again tomorrow.
On the other hand, some activities around the Sakonishi-area was informed from the mid of June. So it is also important to check the relation.
I confirmed that the activities of excavators near the Kamioka mine company office generated the seismic noise enhancement at MCF and IXV as the attached file.
The numbers in the graph completely matched the excavators' activities status by my eyeballs.
- I passed through the construction area and two excavators stopped (no engine sound at this time). I parked my car near the SK entrance and started monitoring the MCF/IXV ground motion via the EDUROM network.
- I noticed the ground motion enhancement and moved my car to the near area of construction area where the mobile phone EM can be scarcely reachable. So I could keep monitoring the MCF/IXV ground motion. Only one excavator was working.
- The second excavator started working. Then the excitation level was enhanced more!
- One excavator stopped. So only one excavator was working.
- One excavator started working. So two excavators were working.
- One excavator stopped. So only one excavator was working.
- One excavator started working. So two excavators were working.
- Both excavators stopped.
- Two excavators started working.
- Both excavators stopped.
The sharp enhancement seemed to correspond to the horizontally large angle swing of arm of the excavator. I could not check the engine status when they stopped motions.
Here is the ground motion comparison between MCF and "E"XYV. By eyeballs, the motion at MCF cannot be seen at EXYV. (Be careful of the vertical scale difference.)
- The distances from the road construction area near the SK entrance to the KAGRA corner station: ~ 400m
- Excavators work for shaping the ground. ---> This is generating the excess seismic noise at MCF/IX(Y)V.
- Dump truck transportation for filling ground.
- The distances from the future tunnel construction area around "Do" area to the KAGRA corner station: ~440m ~ 680m
- Blasting
- Excavators work for removing rocks outside.
- Dump and concrete mixer truck transportation.
- The distances from the Sakonishi construction area to the KAGRA EX station: ~ 1300m
- The distances from the Sakonishi construction area to the KAGRA Corner station: ~ 1800m
- The distances from the Sakonishi construction area to the KAGRA EY station: ~ 4000m
- Excavators work for moving/resetting rocks.
- Rock crushing with a jackhammer.
- Dump and concrete mixer truck transportation
Do this? From GWADW2019 https://agenda.infn.it/event/15928/contributions/88922/attachments/63258/76101/BKamai_GWADW_final.pdf