Hi,
I am finally getting around (being forced) to change a set of scripts to adjust to the latest updates to obspy and came across a number of issues.
The first issue has been discussed in February 2016, and is related to setting sac-header location fields (stla, stlo, evla, evlo). Initially, all these items have values of -12345 (this is a SAC default for unset header values). When I set one of the items, say stlo, it appears that obspy tries to compute the distance and azimuth using the existing -12345 values, which throws an exception from the distance-azimuth calculation (‘out of bounds’, because -12345 is not in the geographic range). Unless you are handling/suppressing the exception, it can toss you out of the current section of your code.
To work around that problem/feature, set lcalda = False, set the location fields and then set lcalda = True. I am not sure rushing off to compute the distance and azimuth is the right thing to do in a header access implementation unless none of the key lats and lons equal -12345. This could be checked in the code if you want to keep the current approach. Or, am I missing something?
Also, I am perplexed by why i cannot store a value in the ‘evdp’ header field. The documentation states that this is “not used”, but it is an essential piece of the header. From the documentation:
"Event depth below surface (meters). [not currently used]"
http://docs.obspy.org/packages/autogen/obspy.io.sac.sactrace.SACTrace.html#obspy.io.sac.sactrace.SACTrace
If I don’t store an earthquake depth in ‘evdp’ where is depth information supposed to be stored? What am I missing here?
Chuck Ammon
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Charles J. Ammon, Department of Geosciences
Penn State University / 440 Deike Bldg / University Park, PA 16802
VOICE: (814) 865 2310 / FAXES: (814) 863 7823 or (814) 863 8724
http://eqseis.geosc.psu.edu/~cammon/
http://www.personal.psu.edu/faculty/c/j/cja12/