How to buy a Seismometer, Part 1

I see it every day.  Observatories need to expand their network and get some money to buy instruments.  They all want broadbands and they all want the iconic Streckeisen STS-2.  The broadband that started it all.  This instrument will solve all of their problems. No matter that the lead times is around 18 months.  No matter that for the most part they don’t need it because their sites are too noisy.  No matter that is too expensive and an older design.  So what to do?

Once you have your budget then the steps you have to take are the following:

  • Determine the frequency you want to look at
  • Determine if the site is any good for those frequencies
  • Determine what resolution you need to see those infrequences
  • Determine the area of interest
  • Determine the topology of the network needed to detect what you need
  • Determine the urgency of the data
  • Determine where you are going to store the data

For example if you want to do automatic locations for local seismicity in real time then you only need a sensor that will detect the frequencies between 1 and 5 Hz and your digitizing can be done with 16 to 20 bits.  You will need GPS timing and you will need internet communications.  In fact you mostly only need the vertical channel.  You will then need at least 8 stations that more or less circle the area of interest.

Eight well install STS-2.5s with Q330s will cost you a minimum of $400,000.00.  The same can be done with eight Titan-SMA’s which installed might cost $80,000 and the same job be done with eight Sixaolas short-period seismometers which can be had for $40,000.00.

In the next few posts of How to buy a Seisomometer I will get into the details of how to to make the above choices.  I have included the first of the charts I will use:

How to choose a Seismometer, part 1: Sensor frequency versus purpose

How to choose a Seismometer, part 1: Sensor frequency versus purpose

P.S. The chart was originally made by Mauro Mariotti of SARA in 2006, it is a tiny bit out o date but not much.  I also worked it over a bit.

— Angel

2 comment(s) on “How to buy a Seismometer, Part 1

  1. Hola Angel,

    I wouldn’t say you only need a vertical component for local monitoring, except if you only want to look at crustal quakes.
    If you want to search for intermediate or deep quakes, you need at least a couple of horizontals, so let’s says for example 4 vertical only and 4 3 components (of course, short-period is still fine).


  2. Jean Marie,

    Yes, that is 100% right and I agree. Burt most countries have several BB’s that can give S’s to constraint the depth. Or instance Panama has 10 BB’s and 15 short period 3 components stations and 56 stations that basically only have a P.


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