From: "Jerry Payton" gpayton880@.......

Date: Tue, 9 Oct 2007 16:46:17 -0500

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