## PSN-L Email List Message

Subject: Re: WinQuake Display Question
From: Bob Hancock carpediem1@.........
Date: Tue, 09 Oct 2007 17:24:42 -0700

```There are both body waves which travel through the earth=B9s mantel and core,
and surface waves which follow the crust.  The P & S waves and their
variations are body waves.  The LQ and LR waves are surface waves and follo=
w
the surface of the earth.  These waves also have different dissipation
rates.=20

Alan Jones program Seismic Waves gives a good presentation of the major

http://www.geol.binghamton.edu/faculty/jones/

Using WinQuake, the wave arrival times are computed based upon standard wav=
e
speeds depending upon the route the waves take, and the depth of the event.

The data is computed using the latitude and longitude of the event and the
station recording the event.

Bob Hancock

On 10/9/07 2:46 PM, "Jerry Payton"  wrote:

> Yes, you answer IS clear.  I suspected that it was a "Great Circle"
> measurement, but wanted verification.
> =20
> However, I was curious about the phase-time travel.  Wave propagation thr=
ough
> the earth is a highly variable thing depending upon the materials it trav=
els
> through, reflections, refractions and etc.  I guess that the "tables" are
> basically averages taken from measurements over the years and reasonably
> accurate.
> =20
> What prompted my question was reading about the construction of the
> "beachball" Focal Mechanism Solution.  They look at the P wave arrival an=
d
> depending upon whether it goes up or down determines one of the factors o=
f the
> final solution.  Thus, exact timing is needed.  If the P wave is arbitrar=
ily
> identified, the solution would be false.  (I think???)
> =20
> Thank you,
> Jerry
> =20
> =20
> ----- Original Message -----
> From: tchannel1@............
> To: psn-l@..............
> Sent: Tuesday, October 09, 2007 3:55 PM
> Subject: Re: WinQuake Display Question
>=20
> Hi Jerry,  "I Think"................Q 1        The p and s and other phas=
es if
> you use them are all based on (time theory)
> The math program knows where you are and where the event took place, it
> converts that info to Miles, also to Degrees.
> It then uses one of several formulas, I use the default formula, to place=
the
> p and s on a time line, which is on the bottom of the Winquake screen.
> =20
> Q2.........The distance is "around the surface" like a string on a globe.
> This is all "great circle" math.
> =20
> So the program is simple for this part, because, it take the event Long. =
and
> Lat,  your Long. and Lat, the time of the event, does the math (the p tra=
vels
> about 10km per second), I calculate it is about 28,000 miles per hour, an=
d
> figure it would take the P, say  12.002 minute to reach you, add that, to=
the
> event time, and places the P on your screen accordingly.
> =20
> It does not read you recording,  you could have recorded a truck or a tra=
in
> and if the event matched your train in would place the p and s, on the ti=
me
> line.
> =20
> Is this clear???????????????????   Ted
>> =20
>> ----- Original Message -----
>> =20
>> From:  Jerry Payton
>> =20
>> To: psn-l@..............
>> =20
>> Sent: Tuesday, October 09, 2007 1:01  PM
>> =20
>> Subject: WinQuake Display Question
>> =20
>>=20
>> =20
>> (Question 1):    On a WinQuake event display are the  P and S arrival ti=
mes
>> showning the ACTUAL arrival times or  shown according to what the table =
says
>> they should be?
>> =20
>> =20
>> =20
>> (Question 2):    Is the distance from the event to  your seismograph com=
puted
>> "through the earth" or "around the  surface?"
>> =20
>> =20
>> =20
>> Thank you,
>> =20
>> Jerry Payton
>> =20
>> =20
>> =20
>> =20
>> =20
>> =20
>> =20
>> =20
>=20

Re: WinQuake Display Question

There=
are both body waves which travel through the earth’s mantel and core,=
and surface waves which follow the crust.  The P & S waves and the=
ir variations are body waves.  The LQ and LR waves are surface waves an=
d follow the surface of the earth.  These waves also have different dis=
sipation rates.

Alan Jones program Seismic Waves gives a good presentation of the major wav=

http://www.geol.binghamton.edu/faculty/jones/

Using WinQuake, the wave arrival times are computed based upon standard wav=
e speeds depending upon the route the waves take, and the depth of the event=
..

The data is computed using the latitude and longitude of the event and the =
station recording the event.

Bob Hancock

On 10/9/07 2:46 PM, "Jerry Payton" <gpayton880@.......> wro=
te:

Yes, you answer IS clear.  I suspected that it was=
a "Great Circle" measurement, but wanted verification.

However, I was curious about the phase-time travel.  Wave propagation =
through the earth is a highly variable thing depending upon the materials it=
travels through, reflections, refractions and etc.  I guess that the &=
quot;tables" are basically averages taken from measurements over the ye=
ars and reasonably accurate.

What prompted my question was reading about the construction of the "b=
eachball" Focal Mechanism Solution.  They look at the P wave arriv=
al and depending upon whether it goes up or down determines one of the facto=
rs of the final solution.  Thus, exact timing is needed.  If the P=
wave is arbitrarily identified, the solution would be false.  (I think=
???)

Thank you,
Jerry

----- Original Message -----
From: tchannel1@............
To: psn-l@..............
Sent: Tuesday, October 09, 2007 3:55 PM
Subject: Re: WinQuake Display Question

Hi Jerry, &=
nbsp;"I Think"................Q 1      &n=
bsp; The p and s and other phases if you use them are all based on (tim=
e theory)
The math program knows where you are and where the event took place, it con=
verts that info to Miles, also to Degrees.
It then uses one of several formulas, I use the default formula, to place t=
he p and s on a time line, which is on the bottom of the Winquake screen.

Q2.........The distance is "around the surfa=
ce" like a string on a globe.   This is all "great circl=
e" math.

So the program is simple for this part, because, =
it take the event Long. and Lat,  your Long. and Lat, the time of the e=
vent, does the math (the p travels about 10km per second), I calculate it is=
about 28,000 miles per hour, and figure it would take the P, say  12.0=
02 minute to reach you, add that, to the event time, and places the P on you=
r screen accordingly.

It does not read you recording,  you could h=
ave recorded a truck or a train and if the event matched your train in would=
place the p and s, on the time line.

Is this clear???????????????????   Ted<=
BR>

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

From:  Jerry Payton <mai=
lto:gpayton880@.......>

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

Sent: Tuesday, October 09, 2007 1:01  PM

Subject: WinQuake Display Question

(Question 1):    On a WinQuake event display are the  P=
and S arrival times showning the ACTUAL arrival times or  shown=
according to what the table says they should be?

(Question 2):    Is the distance from the event to  you=
r seismograph computed "through the earth" or "around the &nb=
sp;surface?"

Thank you,

Jerry Payton

```