Hi Ted,

I'm glad you are getting lots of ideas for your new seismometer location. I
have mine in the wine cellar, on the concrete floor. Temperature is very
stable. No real changes during the day. Over the seasons, it may change 10
degrees F. However when we visit the wine cellar, the alarms go off. Walking
by will give quite a jolt, at least on the screen. But quickly settles down.
I see traffic noise from 6AM to 11PM (freeway 2 miles away) and freight
trains in the middle of the night (1 mile away) and of course the
washer/dryer. It's only 15 feet away but with 6" framed wall with insulation
between. Let us know what you decide to do.

Gary

See http://www.blue-eagle-technologies.com/images/ch1.gif  If you are quick,
the red signal in upper right is the last wine cellar visit.

 

 

From: psn-l-request@.............. [mailto:psn-l-request@............... On
Behalf Of tchannel1@............
Sent: Saturday, August 30, 2008 2:39 PM
To: psn-l@..............
Subject: Re: crawl space under house

 

Hi Bob,  Thanks for sharing...........Presently my sensors are in the
basement on a concrete floor.   Yes I do see people walking upstairs, but
mostly if I place the sensor close to a vertical wall.

My new house set on a new foundation, so as you point out I may get a lot of
noise as the house settles.   We shall see.   All your information is good
to know.

 

Ted

----- Original Message ----- 

From: Bob Hancock   

To: psn-l@.............. 

Sent: Saturday, August 30, 2008 12:40 PM

Subject: Re: crawl space under house

 

Hi Ted -

When we lived in NJ, I operated a 3 channel MET seismometer in the crawl
space under my apartment.   I had the instrument sitting on a hexagonal
cement block of 12 inches across and 2 inches thick, all covered with a
Styrofoam bucket.  The building design included foundation walls that were
placed several feet in the soil, including individual foundations walls
between each apartment.  Although I had the instrument more or less in the
middle of the area, I found that as I walked on the floor above, I could see
that motion on the instrument.  Depending upon your foundation, you may find
that walking around your house will cause deflections of the instruments.  I
have heard similar comments from individuals who have placed instruments in
basements or on garage floors.

When we moved to Arizona, I tried a variety of locations including under my
house, in a nearby storage shed and in my workshop.  None were adequate.  I
finally placed the instrument in the ground, first about 75 feet away and I
could always tell when the washing machine when into the spin cycle.  I
finally moved the instrument about 250 feet from the house where I get a
minimum of wind and cultural noise.  The road is about 400 feet from the
instrument and I can see vehicles striking potholes in the road.  I find
that if I drive my garden tractor within 50 feet of my vault, I can see
movement on the instrument.  

Depending upon your yard size, you might consider a subsurface vault in a
quiet area, away from trees and any buildings.  It is very difficult to
remove cultural noise as I have found.  However, you should be careful and
do not disturb any more dirt than you need.  Dirt once disturbed is
difficult to re-compact and will be a source of noise for a long time to
come as it settles.  I have found that after 1 1/2 years, I still get
occasional ground noise from settling dirt.

Another thought to consider is insulating your instrument from wind
currents.  Seismometers are extremely sensitive to any wind flow and
temperature change.  In my setup, I first covered my instrument with sand
bags, and that did a good job of insulating the instrument from thermal
variation and wind flow.  However, they were hard to remove from the hole,
and I settled on a large bucket lined with fiberglass which sits on top of
the instrument and covers it down to its base.  I have found this to be very
effective and the bucket protects the instrument from both wind flow and
thermal variations.  Even in a sealed seismic vault you need to protect
against errant wind currents caused by uneven thermal heating of the vault
as the sun moves across the sky.

The key for a quiet instrument is reduction of cultural noise and wind
noise.  Things to consider is under a house you will most likely pick up
movement of people in the house, and tilt from the house in times of high
and possibly even moderate winds.  You proximity to trees is another
consideration as the root structure causes ground tilt for a considerable
distance.  Railroad tracks can transmit vibrations for miles.  The worst
rail noise comes from diamonds where one set tracks crosses another set of
tracks.  Major roads that are in poor repair with potholes and lots of
semi-trailers are another source of cultural noise.......Just some thoughts
to consider.

Good luck on your location wherever you choose it.

Bob Hancock

 


----- Original Message ----- 
 
From:  Gary  Lindgren  
  
 
To: psn-l@.............. 
 
Sent: Thursday, August 28, 2008 9:59  AM
 
Subject: craw space under house

Hi All,    I am building a new house.   This house has no basement, but has
a  24"? crawlspace under the house.   I have lots of time, to create a
space for my three sensors, under the house.   I could also place  them in
the garage on the concrete floor.   My thought was to enter  the crawlspace,
and dig a small pit large enough to allow for elbow room, then  line the pit
with concrete blocks to keep dirt away.  Perhaps  covering the floor area
similarly.  Concrete may not be the best  material.   I could also pour a
pad or small footing using  cement.

 

Please any thoughts  on preparing this space?

 

 
 
 

Thanks,  Ted

 

 















Hi Ted,

I’m glad you are getting lots of ideas for your new
seismometer location. I have mine in the wine cellar, on the concrete =
floor.
Temperature is very stable. No real changes during the day. Over the =
seasons,
it may change 10 degrees F. However when we visit the wine cellar, the =
alarms go
off. Walking by will give quite a jolt, at least on the screen. But =
quickly
settles down. I see traffic noise from 6AM to 11PM (freeway 2 miles =
away) and
freight trains in the middle of the night (1 mile away) and of course =
the
washer/dryer. It’s only 15 feet away but with 6” framed wall =
with
insulation between. Let us know what you decide to =
do.

Gary

See http://www=
..blue-eagle-technologies.com/images/ch1.gif 
If you are quick, the red signal in upper right is the last wine cellar =
visit.

 

 





From:=

psn-l-request@.............. [mailto:psn-l-request@............... On =
Behalf
Of tchannel1@............

Sent: Saturday, August 30, 2008 2:39 PM

To: psn-l@..............

Subject: Re: crawl space under house





 



Hi
Bob,  Thanks for sharing...........Presently my sensors are in the
basement on a concrete floor.   Yes I do see people walking =
upstairs,
but mostly if I place the sensor close to a vertical =
wall.





My
new house set on a new foundation, so as you point out I may get a lot =
of noise
as the house settles.   We shall see.   All your
information is good to know.





 





Ted







-----
Original Message ----- 





From: Bob Hancock 





To: psn-l@..............






Sent:<=
/b> Saturday, =
August 30,
2008 12:40 PM






Subject: Re: crawl =
space
under house





 



Hi
Ted -



When we lived in NJ, I operated a 3 channel MET seismometer in the crawl =
space
under my apartment.   I had the instrument sitting on a =
hexagonal
cement block of 12 inches across and 2 inches thick, all covered with a
Styrofoam bucket.  The building design included foundation walls =
that were
placed several feet in the soil, including individual foundations walls =
between
each apartment.  Although I had the instrument more or less in the =
middle
of the area, I found that as I walked on the floor above, I could see =
that
motion on the instrument.  Depending upon your foundation, you may =
find
that walking around your house will cause deflections of the =
instruments.
 I have heard similar comments from individuals who have placed
instruments in basements or on garage floors.



When we moved to Arizona, I tried a variety of locations including under =
my
house, in a nearby storage shed and in my workshop.  None were =
adequate.
 I finally placed the instrument in the ground, first about 75 feet =
away
and I could always tell when the washing machine when into the spin =
cycle.
 I finally moved the instrument about 250 feet from the house where =
I get
a minimum of wind and cultural noise.  The road is about 400 feet =
from the
instrument and I can see vehicles striking potholes in the road.  I =
find
that if I drive my garden tractor within 50 feet of my vault, I can see
movement on the instrument.  



Depending upon your yard size, you might consider a subsurface vault in =
a quiet
area, away from trees and any buildings.  It is very difficult to =
remove
cultural noise as I have found.  However, you should be careful and =
do not
disturb any more dirt than you need.  Dirt once disturbed is =
difficult to
re-compact and will be a source of noise for a long time to come as it =
settles.
 I have found that after 1 1/2 years, I still get occasional ground =
noise
from settling dirt.



Another thought to consider is insulating your instrument from wind =
currents.
 Seismometers are extremely sensitive to any wind flow and =
temperature
change.  In my setup, I first covered my instrument with sand bags, =
and
that did a good job of insulating the instrument from thermal variation =
and
wind flow.  However, they were hard to remove from the hole, and I =
settled
on a large bucket lined with fiberglass which sits on top of the =
instrument and
covers it down to its base.  I have found this to be very effective =
and
the bucket protects the instrument from both wind flow and thermal =
variations.
 Even in a sealed seismic vault you need to protect against errant =
wind
currents caused by uneven thermal heating of the vault as the sun moves =
across
the sky.



The key for a quiet instrument is reduction of cultural noise and wind =
noise.
 Things to consider is under a house you will most likely pick up =
movement
of people in the house, and tilt from the house in times of high and =
possibly
even moderate winds.  You proximity to trees is another =
consideration as
the root structure causes ground tilt for a considerable distance.
 Railroad tracks can transmit vibrations for miles.  The worst =
rail
noise comes from diamonds where one set tracks crosses another set of =
tracks.
 Major roads that are in poor repair with potholes and lots of
semi-trailers are another source of cultural noise.......Just some =
thoughts to
consider.



Good luck on your location wherever you choose it.



Bob Hancock



 



----- Original Message ----- 

 

From:  Gary  Lindgren <mailto:gel@.................>=
;
 

 

To: psn-l@.............. 

 

Sent: Thursday, August 28, 2008 9:59  AM

 

Subject: craw space under house



Hi
All,    I am building a new house.   This house =
has no
basement, but has a  24"? crawlspace under the house. =
  I
have lots of time, to create a  space for my three sensors, under =
the
house.   I could also place  them in the garage on the =
concrete
floor.   My thought was to enter  the crawlspace, and dig =
a
small pit large enough to allow for elbow room, then  line the pit =
with
concrete blocks to keep dirt away.  Perhaps  covering the =
floor area
similarly.  Concrete may not be the best  material. =
  I
could also pour a pad or small footing using  cement.



 



Please
any thoughts  on preparing this space?



 



 

 

 



Thanks,
 Ted



 

 <=
/o:p>