Using JWeed to read seismic data from the RETREAT Project (Post 1)

Notes on getting RETREAT data from the IRIS DMC (6/13/07) -- Experience working on an Intel Mac laptop

FIRST: obtain JWeed from the IRIS website. Install on your computer.

SECOND: obtain ccrypt from sourceforge on the web. There are versions that have executables for many processors and operating systems, but it might be safest to get the source code and compile it in your own environment. First "./configure" then "make" then "sudo make install" on a Mac.

Running JWeed

Three items to remember: 1) the RETREAT network code is YI. There are some other stations in Antarctica that are included in network YI. You might be able to avoid these in JWeed by restricting the stations to a box around Italy. 2) the definition of YI is time-variable. If you ask for the station info when JWeed is set for a time interval in 2007, you wont get the RETREAT stations. 3) the RETREAT and GAIA stations record on the BH? channels, and the INGV network stations record on the HH? channels. You must request both channel types to get data from both sets of stations.

Dont try to move back and forth in JWeed while you are retrieving something from the internet. In particular, the download of stations from the database is tedious, and there is temptation to wander in JWeed. However, I have found that JWeed will halt when you move to a different tab in the GUI. It is smarter to use the Network DataCenter once for each time interval of interest, then use the JWeed-written station file for later requests.

To get the INGV HH? stations, Ive wasted a day trying. HH? channel is not a channel normally found by JWeed. Also the IRIS database cant always find the INGV stations in JWeed. It is a pisser. The key is that JWeed wont find a station that does not have channel that is being requested. So if you ask for BH? channels, only the PASSCAL and GAIA stations appear in YI, not the INGV stations. I find that the request works if you ask for BOTH B* and HH* channels.

The other JWeed "feature" is that you cant create multiple breqfast files without exiting the software. Either the YI network decreases down to a single station on the Antarctic ice cap, the breqfast file hangs, or something else surprises you. Give up! Exit JWeed and start over!

If you have event files and station files, it is possible to run JWeed without accessing the outside DHI servers. However, I had to turn off the internet access for the computer to avoid problems. Also, you cant run JWeed multiple times to create multiple files. Ive had to close JWeed and start over every time.

Here is what seems to work:

1) set IRIS netDC for Jweed in first tab.

2) Set the whole world in the second tab -- it is the default box. You can also specify an epicentral range around a map point. Use the crosshairs icon to the left

3) in third tab, specify magnitude range, depth range, MB MS ML as the magnitudes to use for body-wave records, load the catalogs if they are not there already, choose WHDF (maybe) and specify the time period for gathering events (VERY important!)

4) Save events if you like

5) Map the events, an operation that pops open the second tab again -- in the map specify a small rectangle over Italy for choosing stations

6) in the 4th tab, access the DHI to bring down a list of networks and stations from the server. This can take a long time. When "finished" open the YI folder to verify that the stations desired are there. If only the Antarctic station is there, search the DHI again. If only BH? stations are there and not the INGV stations, start over if you want the INGV stations.

7) Select the YI folder and map the stations. save them to a file if you wish.

8) Go to the generate-request tab. click the "listing" button, rather than the "map" button. wait until the summary file appears in the text window. The program prompts for a file name and write out the summary file automatically. JWeed write the file to the JWEED_HOME directory. Make sure that you have set this environmental variable.

9) Go to the mail-request tab. Fill in the info, choose the Breqfast-IRIS tab to specify the IRIS DMC. Do NOT email the request directly, save it to a file. This allows you to fix any syntax issues easily.

Running CCRYPT

the routine ccrypt has better encryption protection than the old Unix version of crypt. This is great, but IRIS encodes with the old version. Therefore you must use the "u" option:

ccrypt -u < file.seed.crypted > file.seed

and the routine prompts you for the crypting key. I put alias crypt "ccrypt -u" into my .cshrc file

Using Breq_fast

JWeed will generate a breq_fast request. It is smart to save the breqfast file on your home computer in order to fix syntax problems. Some syntax issues crop up intermittently. For instance, JWeed will let you specify multiple channels in the request
e.g. BHZ HHZ, but in the last few days the two items in the breqfast file are not parsed by the DMC software, only the first one is. Parsing the multiple-channel request by changing the breqfast file to "BHZ HHZ" with quote marks WONT WORK. For the YI case you can try to specify ?H? as the channel and the request will obtain both HH? and BH?. BUT, watch the last number before the channel identifier. It should be the number 1, else there will be a syntax error. However, the ?H? trick works in some cases and not others. Therefore I have requested BH? and HH? separately. One can use the same breqfast file twice, since no station has both BH and HH channels.

A number of tests failed to work. I hypothesize that Breqfast wildcarding wont allow '?', only '*' In any case, the last time I sent a breakfast request with the '*' wiildcard and two channel items, the DMC responded as documented. AAAAAUUUUUGGGGHHH!!!!!

Running rdseed on the SEED files

This seems to be OK. The use of summary files is important, because these will synchronize start times for the three components of motion, if possible. RDSEED is not transferring event informationj from the summary file, so there are no epicentral distances and azimuth values (or correct ones!) in the SAC header. It is possible to run rdseed in command-line mode:

rdseed -d -f filename.seed -x filename.summary