Interesting plots (RD11A) - Ideas?

I like looking over the 24 hour charts and looing for interesting things and I have seen a few times these very low frequency (<1hz) one cycle waves that are stronger than most of the vibrations. They only have one cycle and do not taper in or out.
For some info on where the shake is located: It is on the cinderblock foundation to the detached garage (I will move it to the concrete slab once I extend the power cable and Lan cable). I do live in a relatively noise environment during the day with traffic and retail business around, but it quiets down a lot at night.

Has anyone else seen anything like this? I don’t believe it to be anything electronic related as I would expect to see more oscillation in the signal, and I would think it is too quick for the earth below the garage to be swelling.

I don’ t know what they are, but I see them too. Like this one:

However, note the time: 00:24:42 PDT – which is 7 hours offset from UTC. So this was 07:24:42 UTC.
Pulling the data from my shake and looking at that time, we see:

2022-06-16T00:07:24.303000  16806
2022-06-16T00:07:24.313000  16825
2022-06-16T00:07:24.323000  16738
2022-06-16T00:07:24.333000  16583
2022-06-16T00:07:24.343000  16540
2022-06-16T00:07:24.353000  16514
2022-06-16T00:07:24.363000  16545
2022-06-16T00:07:24.373000  16656
2022-06-16T00:07:24.383000  16688
2022-06-16T00:07:24.393000  16754
2022-06-16T00:07:24.403000  16808
2022-06-16T00:07:24.413000  16759
2022-06-16T00:07:24.423000  16695    <<<<<<<<<<
2022-06-16T00:07:24.433000  16626
2022-06-16T00:07:24.443000  16632
2022-06-16T00:07:24.453000  16656
2022-06-16T00:07:24.463000  16691
2022-06-16T00:07:24.473000  16664
2022-06-16T00:07:24.483000  16617
2022-06-16T00:07:24.493000  16603
2022-06-16T00:07:24.503000  16584
2022-06-16T00:07:24.513000  16648
2022-06-16T00:07:24.523000  16648
2022-06-16T00:07:24.533000  16674
2022-06-16T00:07:24.543000  16721
2022-06-16T00:07:24.553000  16742
2022-06-16T00:07:24.563000  16732
2022-06-16T00:07:24.573000  16696
2022-06-16T00:07:24.583000  16700
2022-06-16T00:07:24.593000  16686
2022-06-16T00:07:24.603000  16692

I don’t see it in the data recorded on my shake, so put it down to a glitch in data transmission or recording.

Glad im not the only one, thank you.

I have been seeing them for years on my 4D. I have been logging them when they trigger the alarm I have set up to monitor for quakes. Since Sept of 2019: 67. The majority seem to occur in the late afternoon between 4p to 6p. I can go a month or two without seeing one at times.

My theory is that something is expanding/contracting near the RShake’s vault in the late afternoon heat or when the sea breeze cools things down rapidly. Vynil fencing maybe??? Just theory, however.

Here is a thread I started on the topic about a year ago: The Spike Mystery

A spike from 5/26:

–Steve Caron
RS4D RD29A Chino Hills, Ca

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I have seen some which I also attributed to expansion/contraction of the concrete slab floor on which the shake is resting.

However, many (most) are actually not recorded in the shake data as above. The “real” ones tend to be more than one cycle and spike in both directions (positive and negative). I think we are seeing two things here.

Possibly two things. I checked the data on the spike I posted here and it is in the data. This is the first I have checked. I always can view them in Swam. So, I assumed it is in the recorded data:

47460 5/26/2022 23:38:03.753
48015 5/26/2022 23:38:03.763
48648 5/26/2022 23:38:03.773
49067 5/26/2022 23:38:03.783
49703 5/26/2022 23:38:03.793
49991 5/26/2022 23:38:03.803
50333 5/26/2022 23:38:03.813
50821 5/26/2022 23:38:03.823
50692 5/26/2022 23:38:03.833
51010 5/26/2022 23:38:03.843
50654 5/26/2022 23:38:03.853
50033 5/26/2022 23:38:03.863
50424 5/26/2022 23:38:03.873
50045 5/26/2022 23:38:03.883
49447 5/26/2022 23:38:03.893
49010 5/26/2022 23:38:03.903
48562 5/26/2022 23:38:03.913


I checked another one this morning - this one clearly shows in the data:

2022-06-17T11:39:18.153000 16661
2022-06-17T11:39:18.163000 16653
2022-06-17T11:39:18.173000 16641
2022-06-17T11:39:18.183000 16645
2022-06-17T11:39:18.193000 16240
2022-06-17T11:39:18.203000 15434
2022-06-17T11:39:18.213000 14696
2022-06-17T11:39:18.223000 14010
2022-06-17T11:39:18.233000 13367
2022-06-17T11:39:18.243000 12767
2022-06-17T11:39:18.253000 12252
2022-06-17T11:39:18.263000 11804
2022-06-17T11:39:18.273000 11369
2022-06-17T11:39:18.283000 10990
2022-06-17T11:39:18.293000 10584
2022-06-17T11:39:18.303000 10251
2022-06-17T11:39:18.313000 9968
2022-06-17T11:39:18.323000 9733
2022-06-17T11:39:18.333000 9554
2022-06-17T11:39:18.343000 9306
2022-06-17T11:39:18.353000 9162
2022-06-17T11:39:18.363000 9042
2022-06-17T11:39:18.373000 8868
2022-06-17T11:39:18.383000 8772
2022-06-17T11:39:18.393000 8684
2022-06-17T11:39:18.403000 8617
2022-06-17T11:39:18.413000 8614
2022-06-17T11:39:18.423000 8590
2022-06-17T11:39:18.433000 8579
2022-06-17T11:39:18.443000 8619
2022-06-17T11:39:18.453000 8629
2022-06-17T11:39:18.463000 8670
2022-06-17T11:39:18.473000 8724
2022-06-17T11:39:18.483000 8746
2022-06-17T11:39:18.493000 8847
2022-06-17T11:39:18.503000 8947
2022-06-17T11:39:18.513000 9002
2022-06-17T11:39:18.523000 9116
2022-06-17T11:39:18.533000 9187
2022-06-17T11:39:18.543000 9264
2022-06-17T11:39:18.553000 9423
2022-06-17T11:39:18.563000 9538
2022-06-17T11:39:18.573000 9707
2022-06-17T11:39:18.583000 9845
2022-06-17T11:39:18.593000 9962
2022-06-17T11:39:18.603000 10124
2022-06-17T11:39:18.613000 10241
2022-06-17T11:39:18.623000 10438
2022-06-17T11:39:18.633000 10601
2022-06-17T11:39:18.643000 10755
2022-06-17T11:39:18.653000 10919
2022-06-17T11:39:18.663000 11045
2022-06-17T11:39:18.673000 11204
2022-06-17T11:39:18.683000 11347
2022-06-17T11:39:18.693000 11511
2022-06-17T11:39:18.703000 11659
2022-06-17T11:39:18.713000 11821
2022-06-17T11:39:18.723000 12003

Hi all:

Just popping in here to let you know that I am monitoring this thread.

Very curious.

Are any of you using wifi? Internal to the Raspberry Pi or via some adapter?

Any other Radio Frequency-generating tech in the vicinity?

Thank you. I love how collaborative this Community is.


I may have to go back on my claim that some of these don’t show in the data. I re-checked some that the shake still retains data for, and all are present in the recorded data.

I am using wifi, but it is an external device connected via ethernet to the shake - that is the only active RF device close, other than one end of my ham radio antenna, but that is not in use at the times these occur, and when it does register it doesn’t look too much like this.

The building it is inside of is all metal, not a complete Faraday cage by any means, but it does attenuate a lot of RF (cell, wi-fi, etc).

The power is the supplied PSU plugged into a UPS, which has (supposedly, don’t know how good) filtered and transient suppressed outlets.

I am using WiFi on mine, but also connected via LAN, I will be turning off the wifi probably this weekend. i also originally thought it was the concrete/building, but as it happens at different times, I would have to look at the temperatures outside to make any correlation if its due to the expansion I do live in a noisy area, but with it being such a low frequency, im not sure hoe the RF would effect it. If others are seeing it too, could it be the accelerometer (geophone) is getting triggered by a magnetic field causing it to “lurch” out of position and back to its resting spot?

Thank you for the link, Ill be sure to check it out too

Correct. Data gaps aside, there is no reason whatsoever to ever think that the data seen via the server (e.g., dataview) is in anyway different than that seen on the Shake itself.

Philip and RIch, can you share a photo of your setup?


I will when I get home, currently “working” :slight_smile:

I will also start logging them into a chart to see if there is any correlation to time of day, frequency it happens, outdoor temps, ect

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Rich - me too hahaha

this is almost certainly due to RF.

I can easily reproduce these spikes with, for example, an old Nokia phone. If I set it next to a Shake and sms it, you get this spike.

This is why we recommend not using wifi. In your case, I am certain these spikes will go away when you turn wifi off.


i will defiantly try that when I get home. I had it on because I was having connection issues if I didn’t have wifi and lan on. but in another thread I was shown how to disable it via ssh, just haven’t gotten around to it.

i just disabled the WiFi via the SSH command,From this thread, and I will let you know if I continue to see them, or if it goes away.

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This is how mine is “installed”. You can see from the leave and spiderwebs that it has not been really disturbed for the past few months (time for a spring-clean now though … if spring ever arrives here, we are still waiting.

The Wi-Fi is the white thing above the power sockets.

Checking the times that these occured over the past couple of days (local time)

  • 14:42
  • 00:24
  • 15:11
  • 23:06
  • 04:39

As far as I am aware, no-one using a cell-phone in the barn at 4AM.

The surrounding area, not likely that there is any local RF activity in the middle of the night around here:


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@branden I think you may have convinced me it is RF. I have an old pair of walkie-talkies with 3 power settings. I went up to my RShake in the garage and hit the transmit key. The results are below.

Cobra radios. They are at least 10yrs old and I do not have the manual.

Transmit low power

Transmit high power



Checked my shake’s on-board Wi-Fi - it is OFF.

Checked what 1Kw of RF @ 3.960 MHz (SSB) looks like:

(That’s me checking into a Pacific NW net). The end of the antenna (the high voltage part) is a few feet from the roof of the barn.

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I did turn the Wi-Fi off, but I am thinking, like others have said, its RF interference. There was a spike when I left to work and closed the garage door from the remote. Next thing to try is making a faraday cage to help with blocking out the RF. This has become more of a challenge now to find and stop the spikes than it is a real problem :slight_smile: