KAGRA Logbook

PEM (General)

shinji.miyoki - 8:50 Sunday 07 May 2023 (25124)

M6.5 and M5.8 Earthquakes at Noto peninsula

M6.5 and M5.8 Earthquakes at Noto peninsula happened around May 5th around 14:42 and 21:58 on May 5th. The estimated Shindo was 3 for M6.5 case around KAGRA site.

At present, IMC could not be locked and PR3 alignment has gone out of QPD range (klog#25122).

In the past 10 years, there were 3 times Shindo-3 around KAGRA site on May 19th 2020, May 29 2020, and September 19 2021 (These recovery reports were posted in klog on the same date. The sources are on the border btw Gifu and Nagano: ~30km away from the KAGRA site: Fig.4). In these cases, IMC alignment seemed not be spoiled so much and could be recovered soon. While PR3 alignment was shifted by 1mrad in 2021 case after the PR3 suspension remedy, and a huge amount in 2020 before the remedy. In this time, the oplev spot seemed to be in the range after the first shock. However, the second shock kicked it out of range.

I compared the PEM_SEIS_BS/EXV_GND_EX/NS_OUTPUT on 5/29 2020, 9/19 2021, and 5/5 2023. (Fig1,2,3)

Although the resolution is not good and the max values are saturated, the level of 5/5 and 9/19 seems to be same, except for their duration time. 5/5 has a longer duration.
5/29 seems to be smaller than others even in the same Shindo-3.
Do you have more high-resolution data??

Images attached to this report

Comments to this report:

shinji.miyoki - 10:26 Sunday 07 May 2023 (25127)

I used the data PEM-SEIS_{BS,EXV}_GND_X_BLRMS_30MHZ100. 5/5 peak height was "~10 times" larger than the past data.

So the type-A might be affected a lot more than Type-C/B/Bp?

Images attached to this comment

shinji.miyoki - 10:26 Sunday 07 May 2023 (25128)

I used the data PEM-SEIS_EXV_GND_X_BLRMS_{30MHZ100,100MHz300,3HZ10}.

As I reported, 5/5 peak height was "~10 times" larger than the past data in the range of 30MHz100.

While ~2times larger in the range of 100MHz300, and almost the same in the range of 3Hz10.

Images attached to this comment

shinji.miyoki - 11:50 Monday 08 May 2023 (25142)

I compared the data on 2021/2/13 when M7.3 happened near Miyagi (~ 500km away from KAGRA), and 2022/3/16 when M7.4 happened near Miyagi.

The peaks in 30MHz100 and 100MHz300 are comparable with those on 2023/5/5(M6.5, ~120km away from KAGRA). While the vibrations in 3Hz10 are much smaller than that on 2023/5/5.

Images attached to this comment

takaaki.yokozawa - 13:10 Monday 08 May 2023 (25144)

The earthquake in Miyagi M7.3 might make the saturation of the KAGRA seismometer signals, so please don't believe all results.

Images attached to this comment

25144_1683519027_1331476638_1331476818_K1 PEM-SEIS_EXV_GND_Z_OUT_DQ_TimeSeries.png

takaaki.yokozawa - 13:16 Monday 08 May 2023 (25147)

Also in Noto M6.5 and M5.8 earthqauke

Images attached to this comment

25147_1683519384_Screenshot from 2023-05-08 13-14-56.png

25147_1683519388_Screenshot from 2023-05-08 13-15-45.png

shinji.miyoki - 13:45 Monday 08 May 2023 (25148)

Thank you for your checks. I will search for non-saturated reliable data.

shinji.miyoki - 20:59 Monday 08 May 2023 (25149)

There seems to be a remarkable level down in the seismic noise around 18:00 as the attached Figure.

Top:Earthquake:30MHz100: smooth level came back!
Bottom:Human:3Hz10: Also floor level down in Z and (Y and/or X) although some spike-like peaks appeared.

Images attached to this comment

shinji.miyoki - 8:40 Tuesday 09 May 2023 (25154)

Around 8:30, Z in 3Hz10 became large again. Also the level in 30MHZ100 became larger. EQ swarm was activated again?