Ted,

Is it you that is using a DATAQ device...  ?

a 154 or a 158
PauLC

  -----Original Message-----
  From: psn-l-request@.............. [mailto:psn-l-request@.................
Behalf Of tchannel
  Sent: Saturday, April 21, 2007 1:54 PM
  To: psn-l@..............
  Subject: Re: Time of Quake??


  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 -----
    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:


      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.
           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/


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

           Regards,

           Chris Chapman








Ted,
 
Is it=20
you that is using a DATAQ device...  ?
 
a 154=20
or a 158 
PauLC


  
-----Original Message-----
From: =
psn-l-request@.................
  [mailto:psn-l-request@...............On Behalf Of=20
  tchannel
Sent: Saturday, April 21, 2007 1:54 =
PM
To:=20
  psn-l@..............
Subject: Re: Time of=20
  Quake??


  
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 sensor and I am going through my maiden voyage with=20
      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.=20
    They are often very large.
       =
You can=20
    buy a radio corrected crystal clock for less than $20. They are very =
useful=20
    and are 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=20
    transient data delays.


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

The =
question.

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

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

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

      =20
    Regards,

       Chris=20
    Chapman

<=
/HTML>