In a message dated 30/04/01, sean@........... writes:

> Although the KS36K is designed for deep boreholes to avoid wind and
> barometric deformation noise to allow maximum sensitivity, a shallow hole
> should be adequate for the thermal stability (temperature changes are
> attenuated by approximately the cube root of the depth) needed for 
> general teleseism detection.  I think that the comment by R. Hutt that
> some components are "noisy" means that they still work but have noise
> levels above the original specifications. One would want to install
> one and operate it to see just what the noise level is.

       Sure, but one factor which concerns me is that age of the transistors 
/ microcircuits. I seem to remember that the best that you could get was a 
projected life of 10 years. These units could be quite a bit older.
       As a rough temperature guide, 1 m below the soil surface gets rid of 
most of the daily temperature variations. 10 metres gets a virtually constant 
all year temperature. I have the figures and equations somewhere, if anyone 
is interested. The diffusion equation gives an exponential dependance. 

> If one wants to install and operate one, I think that a 10 ft borehole
> can made with a bucket auger, with a tripod, rope and pulley to lift it,
> (I have been able to go well over 10 meters by adding sections to the 
> auger pipe; not exactly straight, and sometimes hit water).

       You may need to seal the top part of the tube to the surrounding soil 
fairly effectively. This stops heavy rain from running down the outside of 
the casing and drastically altering the temperature at the bottom.

> You can case the hole with a 10' length of schedule 80 ABS pipe. The 
> tripod, made with three 21ft lengths of chain fence corner post tubing 
> (1 1/2"dia) is also useful for lowering the intact instrument into the 
> hole. The limited availability of the installation test sets will 
> require some co-operation, and it may even be possible to pool resources
> and do a collaborative effort in one area, like Denver.

       Apart from the pump and the three valves, there are at least two 
adjusting motors on each sensor that need to be controlled.

Since it is a tri-axial sensor, individual parts of it would
> be essentially useless curiosities. It is designed to work IN
> the borehole casing with the three U,V,W. sensors summed to make
> the orthogonal outputs, as I and Dennis described. I think it would 
> be ill advised to "break it down", which would be to brake it period.
> A single 53 deg. sensor is not a useful seismometer

Dear Sean-Thomas, 

1)       The KS36K units have their max. sensitivity at 53 deg to the 
vertical. If you have all three sensors working fine, there should be no 
serious problems, should there?

2)       Now supposing that you only have two working sensors. You can 
reinstall them for say E/W and W/E alignment. Shouldn't you be able to get 
the vertical sensitivity by just adding the signals, while the opposing E/W 
W/E movements would cancel? If you subtract the signals, the two V signals 
should cancel and the E/W W/E signals should now add? Wouldn't this give one 
standard horizontal and a vertical readout after scaling? I note that the 
internal frame is built in short sections bolted together.

3)       If you are from a school or private individual and just want to 
'record earthquakes', probably mostly teleseisms, does it really matter that 
your system is sensitive to both vertical and single axis horizontal waves? 
OK this is not 'reporting' standards with waveforms that can be looked up, 
but wouldn't it show the P and the S waves OK, possibly even rather better 
than a single axis Lehman? The quake signals that you receive may be 
partially reflected or scattered by local geological features anyway and so 
won't be 'pure'?

       While I agree that the units should not be disassembled if possible, I 
would be interested to hear your views on what alternatives can actually be 
achieved in practice, please?

       Regards,

       Chris Chapman
In a message dated 30/04/01, sean@........... writes:



Although the KS36K is designed for deep boreholes to av
oid wind and

barometric deformation noise to allow maximum sensitivity, a shallow hole

should be adequate for the thermal stability (temperature changes are

attenuated by approximately the cube root of the depth) needed for 

general teleseism detection.  I think that the comment by R. Hutt that

some components are "noisy" means that they still work but have noise

levels above the original specifications. One would want to install

one and operate it to see just what the noise level is.




       Sure, bu
t one factor which concerns me is that age of the transistors 

/ microcircuits. I seem to remember that the best that you could get was a 

projected life of 10 years. These units could be quite a bit older.

       As a rough temperature guide, 1 m below the soil surface gets rid of 

most of the daily temperature variations. 10 metres gets a virtually constant 

all year temperature. I have the figures and equations somewhere, if anyone 

is interested. The diffusion equation gives an exponential dependance. 



If one wants to install and operate one, I think that a
 10 ft borehole

can made with a bucket auger, with a tripod, rope and pulley to lift it,

(I have been able to go well over 10 meters by adding sections to the 

auger pipe; not exactly straight, and sometimes hit water).




       You may 
need to seal the top part of the tube to the surrounding soil 

fairly effectively. This stops heavy rain from running down the outside of 

the casing and drastically altering the temperature at the bottom.



You can case the hole with a 10' length of schedule 80 
ABS pipe. The 

tripod, made with three 21ft lengths of chain fence corner post tubing 

(1 1/2"dia) is also useful for lowering the intact instrument into the 

hole. The limited availability of the installation test sets will 

require some co-operation, and it may even be possible to pool resources

and do a collaborative effort in one area, like Denver.




       Apart fr
om the pump and the three valves, there are at least two 

adjusting motors on each sensor that need to be controlled.



Since it is a tri-axial sensor, individual pa
rts of it would

be ess
entially useless curiosities. It is designed to work IN

the borehole casing with the three U,V,W. sensors summed to make

the orthogonal outputs, as I and Dennis described. I think it would 

be ill advised to "break it down", which would be to brake it period.

A single 53 deg. sensor is not a useful seismometer




Dear Sean-Thomas, 



1)       The KS36K units have their max. sensitivity at 53 deg to the 

vertical. If you have all three sensors working fine, there should be no 

serious problems, should there?



2)       Now supposing that you only have two working sensors. You can 

reinstall them for say E/W and W/E alignment. Shouldn't you be able to get 

the vertical sensitivity by just adding the signals, while the opposing E/W 

W/E movements would cancel? If you subtract the signals, the two V signals 

should cancel and the E/W W/E signals should now add? Wouldn't this give one 

standard horizontal and a vertical readout after scaling? I note that the 

internal frame is built in short sections bolted together.



3)       If you are from a school or private individual and just want to 

'record earthquakes', probably mostly teleseisms, does it really matter that 

your system is sensitive to both vertical and single axis horizontal waves? 

OK this is not 'reporting' standards with waveforms that can be looked up, 

but wouldn't it show the P and the S waves OK, possibly even rather better 

than a single axis Lehman? The quake signals that you receive may be 

partially reflected or scattered by local geological features anyway and so 

won't be 'pure'?



       While I agree that the units should not be disassembled if possible, I 

would be interested to hear your views on what alternatives can actually be 

achieved in practice, please?



       Regards,



       Chris Chapman