Hi Chris, A question about P travel time?  I read somewhere it varies, =
from __km to __km per second.
Does it vary depending on the material, type of earth, that it is moving =
through?
I have calculated, from recordings, a range of 10,000 to 30,000 miles =
per hour. That's a big range.

I would like to have a better understanding of it.   Thanks, Ted
  ----- Original Message -----=20
  From: ChrisAtUpw@..........
  To: psn-l@.................
  Sent: Saturday, April 21, 2007 9:34 AM
  Subject: Re: Time of Quake??


  In a message dated 2007/04/21, Paulc@........ writes:

     =20
    For the past month I have been working on a horizontal pendulum =
sensor and I am going through my maiden voyage with it.
        The clock is accurate to within 10 seconds, I am using the =
Amaseis program, and a 12 bit ADC.


  Hi Paul,

         The P waves may travel at 8.2 km / sec. You need your clock =
accurate to about 1 sec for practical purposes. I suggest that you keep =
a note of the errors for a day or two. They are often very large.
         You can buy a radio corrected crystal clock for less than $20. =
They are very useful and are accurate to 20 mS. They update every hour.=20
         You can also visit http://nist.time.gov/ and cross check =
on-line, but do watch out for transient data delays.


        I would like to try and compare events elsewhere in the world / =
country to my sensor. At this site I can see various locations.

    The question.

        If I know in  when in UTC an event occurred, and where.. how do =
I convert that to a UTC time when the event would arrive at my location, =
if ever.
    In other words how ho long does it take to get here??


     Y
    ou can calculate arrival time using =
http://neic.usgs.gov/neis/travel_times/=20


         and also download tables and charts to measure the distance =
from the P to S delay time.

         Regards,

         Chris Chapman








Hi Chris, A question about P travel =
time?  I=20
read somewhere it varies, from __km to __km per second.
Does it vary depending on the material, =
type of=20
earth, that it is moving through?
I have calculated, from recordings, a =
range of=20
10,000 to 30,000 miles per hour. That's a big range.
 
I would like to have a better =
understanding of=20
it.   Thanks, Ted

  
----- Original Message ----- 
  From:=20
  ChrisAtUpw@....... 
  
To: psn-l@.............. 
  
Sent: Saturday, April 21, 2007 =
9:34=20
  AM
  
Subject: Re: Time of =
Quake??
  

In a=20
  message dated 2007/04/21, Paulc@........=20
  writes:

    
  For the past month I have been working on a horizontal =
pendulum=20
    sensor and I am going through my maiden voyage with it.
    The clock=20
    is accurate to within 10 seconds, I am using the Amaseis program, =
and a 12=20
    bit ADC.

Hi=20
  Paul,

       The P waves may =
travel at=20
  8.2 km / sec. You need your clock accurate to about 1 sec for =
practical=20
  purposes. I suggest that you keep a note of the errors for a day or =
two. They=20
  are often very large.
       You can =
buy a=20
  radio corrected crystal clock for less than $20. They are very useful =
and are=20
  accurate to 20 mS. They update every hour.=20
  
       You can also visit=20
  http://nist.time.gov/ and cross check on-line, but do watch out for =
transient=20
  data delays.


      I would like to =
try and=20
    compare events elsewhere in the world / country to my sensor. At =
this site I=20
    can see various locations.

The =
question.

    If I know=20
    in  when in UTC an event occurred, and where.. how do I convert =
that to=20
    a UTC time when the event would arrive at my location, if =
ever.
In other words =
how ho long=20
    does it take to get here??

   Y
  ou can calculate arrival time using http://neic.usgs.gov/nei=
s/travel_times/=20
    

      =20
  and also =
download tables=20
  and charts to measure the distance from the P to S delay=20
  time.

      =20
  Regards,

       Chris =
Chapman