G515:  Lesson 3

Accessing Data from IRIS DMC

Objective:
This lesson will teach you steps required to download data from the IRIS Data Management Center through the interface they call "Wilber" and convert the download file into a form you can work with using the Antelope processing programs.

Follow these steps:

  1. Go to the   IRIS DMC WEB SITE
  2. On the left Frame labeled Quick Links there is a link with the lable Wilber.  Follow that link
  3. Follow the links on the right side of the page that comes up to use "Wilber II, son of Wilber"  (You may want to bookmark this page when it comes up to avoid this path later)
  4. Select a quarter (Q1, Q2, etc.) and a year.  Newer data has "Spyder" events, which means they were downloaded shortly after they occurred and have not been quality controlled.  If you look at data more than about 1 year old, the Spyder data are gone because they are superceded by "Farm" events (higher quality)  You will get a display something like this:
  5. Point at a region of earthquakes with your mouse and left click with your mouse.  You will get a list of events within the specified "Selection Radius".  Experiment with the "Selection Radius" widget varying the search radius and area you select to get the feel for this interface.
  6. Select an event from the list by clicking on the date field
  7. A list of network codes comes up that describes different groups of stations run by different groups.  Select II and IU under the IRIS GSN/GDSN group and click Proceed
  8. A lengthy form comes up.  It would be a good idea to print this page for later reference now.
  9. Note that the form is divided into two parts:  (1) station codes, and (2) channel codes.  You can use this to select from 1 to hundreds of channels of recordings of the event you have selected.  For now choose ALL stations and only the L channels (fyi, the codes are this:  B - broadband, L - long period, S-short period, H - high frequency broadband, and E - triggered short period data.   Wilber normally has only B, L, and S channels.   The second letter is normally an H and the third letter in the code defines the orientation of the sensor: Z=vertical, N=north-south, and E=east-west).
  10. While you are here push the button labelled Map of Responding Stations.  Try to print this image (The way to do this is browser and system dependent so the keyword is "try".  It would be useful to have this picture next week when we discuss the event you chose.)
  11. Fill in the Personal Information typein fields in the lower right part of the page and check the Notify me by email when complete field.  Then push the Process Request button (you are selecting the default data format which is called "SEED" for Standard Earthquake Exchange Data).
  12. A page comes up showing where you are in the queue for getting the data you requested.  You can sit and wait for it to tell you it is finished, or wait until it send you email to tell you were to find the data.
  13. Grab the data from iris by anonymous ftp.  You can use command line ftp to ftp.iris.washington.edu or a web browser pointing at  ftp://www.iris.washington.edu/pub/userdata   You should find your data in a directory under the name you  typed as your Personal Information earlier.  Be aware this file can easily get pretty large and could exceed your file quota on nations.  You should probably place it in the /scratch area to prevent a quota violation in the download process (I assume you all have done enough web work to know how to do this.)
  14. When the file is completely transferred run the program called psd2db.  First read the output from "man psd2db" to see the full usage of this command.  (Note I have seen psd2db fail on DMC generated SEED files.  If something goes wrong, try sd2db.  The former is nicer to use because it does not require making a second copy or the data.  The later can generate a large number of files that can be overwhelming.
  15. Run dbpick on the output "database" and play with the data a bit.  Some things to experiment with are: