[SAC-HELP] units of EVDP in SAC

[Arthur Snoke]

Comments on the two responses I got so far:

1) Because traveltime did not work in SAC/IRIS, in the Help file for 
sss/traveltime 
<http://www.iris.edu/software/sac/commands/sss.com/traveltime.html> we 
recommend using taup_setsac.  As with RDSEED, the default is meters for 
EVDP.

2) I thought about some variant of George's macsac 1000 switch between 
meters and kilometers, but not having worked with very shallow events (of 
any kind) I was not sure where the threshold should be set. A 0 value is 
no problem, but does one use focal depths of 0.5 km?  Patly because of my 
testing with traveltime, I am planning to changed the EVDP for fg/seismo 
to 15 km.

On Tue, 19 Jul 2011, Arthur Snoke wrote:

> To my knowledge, since IRIS/SAC v100, EVDP (focal depth in the SAC 
> header) has not been used in any SAC command.  Please let me know if 
> there are commands I have overlooked.
>
> Because of historical reasons, EVDP (focal depth) in SAC has the units 
> according to the SAC manual.  RDSEED converts EVDP from kilometers 
> (which it is in blockette 71 in SEED) to meters when writing SAC 
> waveforms.
>
> For v101.5, the units of EVDP will be of interest because we will (re) 
> introduce a version of the TRAVELTIME command, in which for waveforms 
> with a defined location and origin time one can calculate arrival times 
> for body-wave phases using the iaspei-tau tables for either ak135 or 
> iasp91 velocity models.  For this command, the units of EVDP matter.
>
> I personally would like to evolve towards having kilometers being the 
> default unit for EVDP.  As a first step, kilometers would be the default 
> choice for EVDP in TRAVELTIME.
>
> The point of this note is a canvass of the community to find if there are any 
> problems with using KM rather than M for EVDP.  Let me know if there are 
> other programs that read SAC files and use EVDP assuming it is in meters.
>
> Arthur