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.
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:
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
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:
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?
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 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.
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.
@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.
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
