Posted on by Jón Frímann

Few words about my geophone network

As many know. I run a geophone network in Iceland. This is my personal network. I have for most part funded it all on my own. But the last two geophones where exception to that. As I did fund them with donations from this web site. That made it possible to setup geophones at Eyrarbakki and at Skeiðflöt, a geophone that is close to Katla volcano.

My geophone network is not complex. It is build up on Mark Products 4.5 Hz 3 component geophone, like this one here. I also have to use analog to digital board and an amplifier. Both I buy both from the same supplier. I also have to use a PC with every geophone station. That is the hardest part of the setup, as PC often fail without reason and with age. For that reason I plan to move to something else in the future. Something that is not PC powered. Having this geophone network allows me to watch the areas where I keep them in real time if something of interest happens. Like an earthquake swarm or a eruption.

Sensitivity of the geophone network

I have setup my geophone network in a such way that it is sensitive to earthquakes. The smallest earthquakes that I can detect in a good weather is somewhere around -2.0ML really close to the geophone. This means in the instance of Katla volcano, that I can see earthquakes down to ML0.2 in magnitude. But I did that this evening, and I did detected that earthquake trough an high noise level. In the case of Heklubyggð geophone (Hekla volcano) and Skeiðflöt (Katla volcano). I am clearly going to see any harmonic tremor that those two volcano are going to make when an eruption starts, when ever that might be.

Wind noise is an constant problem on my geophone network. There isn’t anything that I can do about it. As isolating setup requires a lot of money and a lot of work to setup and maintain properly. Something that I cannot afford. I also cannot do this. But I do try to insulate the geophones with some cheap ways, like keeping them indoor and placing an cheap plastic bucket on top of them with some insulating material. But that does not work in the worst storms that pass over Iceland during the winter. But works well against minor noise in the environment.

All that my geophones record can be viewed online here. The images are updated every 5. min.

26 Replies to “Few words about my geophone network”

  1. Thanks for the info Jon – very interesting, although the one at Katla is wahed out with black – a little too sensitive perhaps?
    Glad to hear that they are all up-and-running

    1. It is not too sensitive, there is just a lot of wind and ocean wave noise on that location. I can tell by looking at IMO sensors that are close to the location of my geophone.

  2. Jon is there a low-power device that can run linux to do the monitoring, like a consumer grade router? My linksys has no hard drive, uses very little power and such so that it has no moving parts so there’s no mechanical breakdown. It runs linux…. Is your geophone monitoring software Windows-only?

    1. Currently is my geophone monitoring software Windows only. But I plan to write my own version when I have learned programming in few years time. Running it on device like Linksys should not be any problems when the time comes.

      But it is going to take some doing on my part until this is ready.

      1. Jon you can avoid the months/years of work studying programming and contract it out. There are websites where you can post your project and programmers will bid on it. Alternatively, maybe there is already software out there to meet your needs (I don’t know).

  3. What computing power (cpu, memory, etc) do you need on the computers at your geophones? What communication interfaces are needed?

      1. So did you think about a netbook-type of computer? They are small and have low power consumption and they are not too expensive.

  4. This might be a stupid question but …

    I watched a documentary about earthquakes a few months back, and the scientists demonstrated how they set up remote solar powered geophones …

    What they did was to dig a 1 meter deep hole in the ground (approx 30-50 cm diameter) fill it partly with sand, put the geophone in, and then cover it all up again.

    Wouldn’t this isolate for wind pretty decently?

    TH

    1. I tested something similar at Heklubyggð geophone and at Hvammstangi geophone stations few years ago. It did not work well. There where a lot of issues with that type of setup. Problems with the connection cables, wind noise was even more and other noise was even more visible on my geophones then when it was inside.

      Here is a good pdf on how IMO setups there own SIL stations. It is in Icelandic, but it has pictures of the SIL setups.

      http://www.vedur.is/media/vedurstofan/utgafa/greinargerdir/2005/05001.pdf

  5. Another thing: is it possible to configure the time loop in your helicorder graphics? For Skeiðflöt a shorter loop could be useful so that we can distinguish the single hours in the plot. This more or less completely black plot doesn’t help the public much.

      1. Yes, I know this, but it would be nice to see the hourly signal spread out a bit wider. So maybe only the last 12 hours instead of 24 on the same graphic size. This way it would be easier to read even with high noise.

      2. I can control the thickness of the images in the program. But the downside is that if I scale it too high up, it gets really hard to see the earthquakes that take place.

        With current setting I can see small earthquakes down to ML1.0 on the sensors if there is not too high noise. Too high settings does not make it easier to read if there is high noise, as is the case with the geophones at the south coast of Iceland.

  6. Skeiðflöt geophone image is not updating due to internet connection issues. That should be resolved tomorrow I hope. Far as I know, the geophone computer it self is continuing to record data and saving gif images. They are not just reaching the internet at the moment.

  7. The problem with wind, is it produce noise in a wide range of frequency..its not easy to remove that noise even applying filters.

    About removing a desktop pc, i also have that problem..but i´m thinking on getting a Raspberry Pi for Linux or working with a microcontroller connected directly to a router, which sends the data to virtual server in Linux or Windows, but it requires a good internet connection. None is a easy solution.

    In good weather conditions, what is the magnitude/distance you can detect? ex: M1.0 up to xx kilometers, M2.0 up to xx km, etc..

    Regards,
    Geo.

    1. I can see a ML1.3 at the distance of 30 km in best of weather. But this does not only depends on the wind. This also depends of fracture, the crust that the earthquake wave is passing trough the rocks and so on. So sensitivity varies from location of an earthquake.

  10. May I ask you what software you use to capture your quake data, and how you get your images to “stream” live? I assume you are saving an image file every five minutes and then having an FTP client upload it? I should have a 1hz vertical instrument setup in the UK by the end of the month and am wondering how best to do this. I have Amaseis on an XP computer for my logging.

    Rob

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