Hi Claire,
I don't fully understand your question, but it seems to me that you are confusing "station information" with "metadata". In my view, these two things are the same. Metadata is downloaded as StationXML files, which contains all the necessary information such as station locations, operating periods, and instrument responses.
You can set the location of where the XML files are stored using the "stationxml_storage" argument in the Mass Downloader module.
Hope that makes sense, and feel free to ask if you need any more information (
Thanks,
Steve
Dr. Stephen Hicks
Postdoctoral Research Fellow in Passive Source Seismology
University of Southampton
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Ocean and Earth Science, National Oceanography Centre Southampton
Hi Steve,
Thanks a lot for your reply and sorry for not formatting my question well. Here is a detailed description of my question.
I hope to retrieve the records at certain stations (like some TA stations) from events during a certain period (for example, records of all the events within 2010-2017 with magnitudes over 6.5) and save them as sac files. I tried to use the mass downloader (specify the time period based on events in a catalog) but when I looked at the headers in the output sac files, I failed to find the information of the events (like origin time, magnitudes…). So I guess my question is how I can associate the event information with the waveforms that I downloaded using the mass downloader. If I cannot, I wonder if there is any way to download the large dataset and associate the event information together with it using obspy?
Thanks,
Claire
Hi Claire,
you have to do this manually. The mass downloader downloads information
about waveforms and stations - it knows nothing about events.
Additionally real world data is never just data from a single events but
it records whatever the wavefield at each receiver location looks like
so the association of waveforms to events in general is not that
meaningful but always tied to certain applications.
So what I assume you are currently doing is reading the resulting
MiniSEED files from the mass downloader and writing them out as SAC
files. These files will have neither station nor event information (as
neither is present in MiniSEED and ObsPy thus does not know them). You'd
have to manually fill in the headers before you write them to SAC.
If you really need to convert to SAC then this is what you have to do;
otherwise I can recommend one of two things:
* Run the mass downloader once per event and store the waveforms,
StationXML files, and the event in a separate file. Then you can always
find what you need without forcing the data into SAC where lots of
information might get lost.
* Sorry for the self-advertisement, but have a look at this - it has
been designed more or less for the use case you describe:
http://seismic-data.org/ - The Python API
(http://seismicdata.github.io/pyasdf/) is built using ObsPy so
transitioning is straightforward.
Cheers!
Lion
Hi Lion,
Got it. Thanks for your detailed reply!
Claire