Geoff
Along that line, a P wave being a pressure wave and a s wave being a shear =
wave. It seems that if one could see two directions simultaneously during a=
n event one be able to combine the p wave vectors and obtain the direction =
of max and min p wave contribution and thus the approx direction of the eve=
nt. I thought one could make a liquid filled cube sensor with a piezoelectr=
ic disk in each face. Opposing faces would go into an instrumentation amp t=
o measure the seismic forces on the liquid inside. To increase the mass in =
each face the center of each face could have a perpendicular tube with the =
piezo disk at the end of the tube. It would look like a kids "jack". I buil=
d one but didn't get the electronics complete. Since a peizo measures veloc=
ity, there may be a better way to measure pressure on each face=A0 (diaphra=
m with displacement sensor?).=20
Regards
Barry


--- On Mon, 9/28/09, Geoffrey  wrote:

From: Geoffrey 
Subject: Re: Seismometer Siting
To: psn-l@..............
Date: Monday, September 28, 2009, 9:27 AM

The question I have is thus:
(plz ignore whatever you do not like)

Do you need a P wave first to tell
the following is an S wave ?

What tells you what when either may look the same.

A vertical polarized S wave ?
A horizontal P wave at the surface ?
A vertical P wave at the surface ?

It seems to me you need one to ID the other
or they differ significantly in some other attribute.
Like frequency.

What you guys say here does not yet make sense to me.

Direction of motion tells me nothing for only a single wave
since I can not see in three dimensions with a single sensor.

I am not looking for the same things as yourselves.
Only first time of arrival.

If I could have a single signal no matter what the
direction that is OK for me.

But I would need according to my understanding
three different sensors sampled at the same identical time instant
to recreate through Mathematics the single magnitude
I am looking for in the display.
I just cant afford ($$$) that kind of luxury
(Never have been able and never will be able).

I really like the idea of Forrest MIMSIII for a horizontal
sensor which is planar and not linear in design.
One pendulum and one vertical and possibly
summing the two together would cheaply let an amateur
see all three dimensions ?
I have not tried this yet but have seen very good
non-dimensional horizontal signals from his design.
It will respond 360 degrees with a single sensor in
the horizontal plane. But that's not right for
most professionals. Just peoples like myself.
NON-SCIENTIST, PSYCHOLOGICALLY DISABLED by PHD peoples AGAINST MY WILL.
LOL, talk about frustrations.

Regards;
geoff

ps, People are nastier than you can ever imagine and a PhD can
make one even worse than nasty. sort of like hitler was to whomever.


----- Original Message ----- From: "Brett Nordgren" 
To: 
Sent: Monday, September 28, 2009 8:21 AM
Subject: Re: Seismometer Siting


> Geoffry,
>=20
> It relates to the direction of the ground oscillations caused by differen=
t phases.=A0 P waves, more or less, vibrate at right angles to S waves.=A0 =
So, *for a particular quake*, if you point your sensor in the direction of =
the arriving P waves in order to see them the best, you would then have to =
turn it by 90 degrees to pick up the S waves most strongly, something like =
aiming a directional radio antenna.
>=20
> With two or three-axis sensors the pointing can be done mathematically wi=
th a computer, working on the saved data, rather than by actually rotating =
the sensor, which allows you to easily estimate the direction of the source=
 of the quake.
>=20
> Brett
>=20
> At 07:37 AM 9/28/2009 -0700, you wrote:
>> It seems silly to me that you can differentiate between
>> various types of disturbances in any way except through
>> frequencies. Even P waves can present themselves
>> with motion or deformation in almost any direction.
>> We live at a phase boundary between air and earth
>> where waves will meet a melodramatic velocity change.
>> Where P can become S and vice versa.
>>=20
>>=20
>> ----- Original Message ----- From: "GPayton" 
>> To: "PSN Network List" 
>> Sent: Sunday, September 27, 2009 11:14 AM
>> Subject: Seismometer Siting
>>=20
>>=20
>>> Over and over, I have read that normally a seismometer is sited for N-S=
, E-W, and Vertical sensing.
>>> However, I just read a paragraph in An Introduction to Seismology, Eart=
hquakes and Earth Structure about a seismometer in Hawaii that "was oriente=
d to receive S phase signals."=A0 How is that accomplished?
>>> I could venture a guess, but probably would be wrong.
>>> Thanks,.
>>> Jerry Payton
>> __________________________________________________________
>>=20
>> Public Seismic Network Mailing List (PSN-L)
>>=20
>> To leave this list email PSN-L-REQUEST@.............. with the body of t=
he message (first line only): unsubscribe
>> See http://www.seismicnet.com/maillist.html for more information.
>=20
> Watch our wiggles
> http://bnordgren.org/seismo/gif_images.htm
>=20
> or watch some very very good wiggles
> http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/ANMO_24hr.html
>=20
>=20
> __________________________________________________________
>=20
> Public Seismic Network Mailing List (PSN-L)
>=20
> To leave this list email PSN-L-REQUEST@.............. with the body of th=
e message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
>=20
__________________________________________________________

Public Seismic Network Mailing List (PSN-L)

Geoff
Along that line, a P wave being a pr=
essure wave and a s wave being a shear wave. It seems that if one could see=
 two directions simultaneously during an event one be able to combine the p=
 wave vectors and obtain the direction of max and min p wave contribution a=
nd thus the approx direction of the event. I thought one could make a liqui=
d filled cube sensor with a piezoelectric disk in each face. Opposing faces=
 would go into an instrumentation amp to measure the seismic forces on the =
liquid inside. To increase the mass in each face the center of each face co=
uld have a perpendicular tube with the piezo disk at the end of the tube. I=
t would look like a kids "jack". I build one but didn't get the electronics=
 complete. Since a peizo measures velocity, there may be a better way to me=
asure pressure on each face  (diaphram with displacement sensor?).
 
Regards
Barry


--- On Mon, 9/28/09, Geoffrey <gm=
voeth@...........> wrote:

From: =
Geoffrey <gmvoeth@...........>
Subject: Re: Seismometer Siting
=
To: psn-l@..............
Date: Monday, September 28, 2009, 9:27 AM
The question I have is thus:
(plz ignore what=
ever you do not like)

Do you need a P wave first to tell
the foll=
owing is an S wave ?

What tells you what when either may look the sa=
me.

A vertical polarized S wave ?
A horizontal P wave at the surf=
ace ?
A vertical P wave at the surface ?

It seems to me you need =
one to ID the other
or they differ significantly in some other attribute=
..
Like frequency.

What you guys say here does not yet make sense =
to me.

Direction of motion tells me nothing for only a single
 wave
since I can not see in three dimensions with a single sensor.
<=
br>I am not looking for the same things as yourselves.
Only first time o=
f arrival.

If I could have a single signal no matter what the
dir=
ection that is OK for me.

But I would need according to my understan=
ding
three different sensors sampled at the same identical time instant<=
br>to recreate through Mathematics the single magnitude
I am looking for=
 in the display.
I just cant afford ($$$) that kind of luxury
(Never =
have been able and never will be able).

I really like the idea of Fo=
rrest MIMSIII for a horizontal
sensor which is planar and not linear in =
design.
One pendulum and one vertical and possibly
summing the two to=
gether would cheaply let an amateur
see all three dimensions ?
I have=
 not tried this yet but have seen very good
non-dimensional horizontal s=
ignals from his design.
It will respond 360 degrees with a single
 sensor in
the horizontal plane. But that's not right for
most profes=
sionals. Just peoples like myself.
NON-SCIENTIST, PSYCHOLOGICALLY DISABL=
ED by PHD peoples AGAINST MY WILL.
LOL, talk about frustrations.

=
Regards;
geoff

ps, People are nastier than you can ever imagine a=
nd a PhD can
make one even worse than nasty. sort of like hitler was to =
whomever.


----- Original Message ----- From: "Brett Nordgren" &l=
t;brett3nt@.............>
To: <psn-l@..............>
Sent: Monday, September 28, 2009 8:21 =
AM
Subject: Re: Seismometer Siting


> Geoffry,
> 
=
> It relates to the direction of the ground oscillations caused by diffe=
rent phases.  P waves, more or less, vibrate at right angles to S
 waves.  So, *for a particular quake*, if you point your sensor in the=
 direction of the arriving P waves in order to see them the best, you would=
 then have to turn it by 90 degrees to pick up the S waves most strongly, s=
omething like aiming a directional radio antenna.
> 
> With two=
 or three-axis sensors the pointing can be done mathematically with a compu=
ter, working on the saved data, rather than by actually rotating the sensor=
, which allows you to easily estimate the direction of the source of the qu=
ake.
> 
> Brett
> 
> At 07:37 AM 9/28/2009 -0700, y=
ou wrote:
>> It seems silly to me that you can differentiate betwe=
en
>> various types of disturbances in any way except through
&=
gt;> frequencies. Even P waves can present themselves
>> with m=
otion or deformation in almost any direction.
>> We live at a phas=
e boundary between air and earth
>> where waves will meet a
 melodramatic velocity change.
>> Where P can become S and vice ve=
rsa.
>> 
>> 
>> ----- Original Message ----- Fro=
m: "GPayton" <gpayton@.............>
>>=
 To: "PSN Network List" <PSN-L@..............>
=
>> Sent: Sunday, September 27, 2009 11:14 AM
>> Subject: Sei=
smometer Siting
>> 
>> 
>>> Over and over, I =
have read that normally a seismometer is sited for N-S, E-W, and Vertical s=
ensing.
>>> However, I just read a paragraph in An Introduction=
 to Seismology, Earthquakes and Earth Structure about a seismometer in Hawa=
ii that "was oriented to receive S phase signals."  How is that accomp=
lished?
>>> I could venture a guess, but probably would be
 wrong.
>>> Thanks,.
>>> Jerry Payton
>> _=
_________________________________________________________
>> 
&=
gt;> Public Seismic Network Mailing List (PSN-L)
>> 
>>=
; To leave this list email PSN-L-REQUEST@SEI=
SMICNET.COM with the body of the message (first line only): unsubscribe=

>> See http://www.seismicnet.com/maillist.html for more informatio=
n.
> 
> Watch our wiggles
> http://bnordgren.org/seismo/gif=
_images.htm
> 
> or watch some very very good wiggles
&g=
t; http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/AN=
MO_24hr.html
> 
> 
> ________________________________=
__________________________
> 
> Public Seismic Network Mailing =
List (PSN-L)
> 
> To leave this list email PSN-L-REQUEST@.............. with the body of the message (f=
irst line only): unsubscribe
> See http://www.seismicnet.com/maillist.html=
 for more information.
> 
____________________________________=
______________________

Public Seismic Network Mailing List (PSN-L)
To leave this list email PSN-L-REQUEST=
@.............. with the body of the message (first line only): unsubsc=
ribe
See
 http=
://www.seismicnet.com/maillist.html for more information.

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