Hello Jón Frímann,
{I copy paste your name since not able to make these foreign characters}

I am located in a residential area
which is very noisy with vehicular traffic.
It resides on Alluvial or Valley fill of possibly 800 feet in depth.
this means, Ideally, no roads within 800 feet of the sensor.
I got one residential road maybe 20/30 feet away.
I got air conditioners all around here in this hot climate.

1. you got to isolate the building Foundation you live in from your sensor.
   [eg cut a slot around the foundation on which the sensor resides]
   [might be illegal/dangerous for the foundation to do]
   [put the sensor => 2ft underground away from the/any building]
2. you need to limit your bandwidth between
    0.04 and two HZ, the narrower the bandwidth
    the less the noise.
3. you need to equalize right from the preamp
    or your preamp might become jammed
    by much higher frequencies.
   The higher frequencies drive the preamp
   into saturation and cutoff which essentially makes
   it blind to everything else meaningful.
   Equalization is simply the process of
   of an N=1 LPF at like 10 to 30 seconds.
4. You must also have some kind of antialize
    filter, like N=8 LPF at 5 to 10 Hz
    the Fco will depend upon your chosen sample rate.
    [I recommend a sample rate between 18 and 25 SPS.]
   BEFORE your signal gets into the A/D converter.
   [Antialize about 9 or 10 Hz with n=8 LPF Butterworth]

Your signals will not be perfect, but usable.

If you do not do these things you can forget
seeing distant quakes with any regularity.
You then go into the mode
of looking only for local or regional events
with your amp set for low gain.

These things I have proven to myself
over like 17 years of playing around
with seismic signals.

Schnitzelbank & Prosit,
geoff

-----Original Message----- 
From: Jón Frímann
Sent: Saturday, April 16, 2011 10:50 PM
To: PSN-Postlist
Subject: Recording earthquakes in a big city

Hello all,

In a few years time I am going to move to Germany (after I move back to
Iceland in June 2011), close to the West Eifel Volcanic Field
(http://www.volcano.si.edu/world/volcano.cfm?vnum=0100-01-)

It might well be that the smaller towns don't fit my plans. As I am
going to try avoding owning a car in Germany.

The populations in the towns and cities are from 10.000 (Daun) and up to
1 million (Köln).

But I want to know how it is to record a earthquakes in big towns. I am
currently living in Denmark, in Sřnderborg. That town has a popluation
close to 28.000 people. There is a lot of noise on my geophone. But I am
up on the 3rd floor (2nd floor danish system). So the resaults that I am
getting a bit noise because of this.

Does anyone here have experience on how to record earthquakes in larger
towns ? Is it possible to start with ?

Regards,
Jón Frímann.

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