Introduction

This tutorial shows how to acquire earthquake waveforms from data centers.

The data centers are used to provide SEED volumes for regional moment tensor inversion.

The source inversion is initiated by a "DO" script that looks like the following example:

#!/bin/sh 
# valid regions
# REG    Region             FELTID  VELOCITY_MODEL
# HI    Hawaii              hi        [Not implemented June 23, 2007]
# SAK    Alaska             ak        WUS  (to 69 km deep)
# NAK    Alaska             ak        CUS  (in continent from Rockies -no deep)
# CA    California          ca        WUS
# PNW   Pacific Northwestrn pnw       WUS
# IMW   Intermountain west  imw       WUS
# CUS   Central US          cus       CUS
# NE    Northeastern US     ne        CUS
# ECAN  Eastern Canada      ous       CUS (in continent from Rockies)
# WCAN  Western Canada      ous       [Not implemented June 23, 2007]
#####
# Command syntax:
#DOCWBREG YEAR MO DY HR MN SC MSC  LAT     LON    DEP  MAG REG  NEIC FELTID STATE/COUNTRY
#####
DOIRIS "2013" "01" "05" "08" "58" "19" "000" " 55.368" " -134.621" "9.8" " 7.48" "CUS" "c000ejqv" "US/c000ejqv"   "Canada"

The DOIRIS script sets up the directory structure, instructs the user to place the SEED volumes in a subdirectory, and then
unpack then, and finally run the DOFINISH script:

1. PLACE THE SEED_VOLUME FROM IRIS in /backup/rbh/PROGRAMS.310t/MECH.NA/20130105085819/20130105085819
   cp SEED_VOLUME /backup/rbh/PROGRAMS.310t/MECH.NA/20130105085819/20130105085819
2. UNPACK the SEED_VOLUME FROM IRIS as follows
   cd  /backup/rbh/PROGRAMS.310t/MECH.NA/20130105085819/20130105085819
   cd Sac 
   rdseed -f ../SEED_VOLUME -R -d -o 1
   [Note use the name of the downloaded file for SEED_VOLUME, e.g., 20090116.seed]
3. Return to the top level directory where you started:
   cd /backup/rbh/PROGRAMS.310t/MECH.NA
4. enter the command:
   DOFINISH
The following sections describe how to get SEED volumes from various data centers.

Earthquakes Canada

Natural Resources Canada/Ressources naturelles Canada provides access to waveform data through their autodrm site. The web page is very easy to use. There are some limitations on the size of the download request, and of course some shortcuts for easier access.

The autodrm request form starts with an the users Email address. When the request is complete, an Email to the user is sent giving the location for FTP access.

Because of the limitation on file downloads, I first run the script DOGSC to get a list of stations ordered by epicentral distance. I use this is select stations for regional moment tensor inversion. The script is available from the next link - just download and save,

DOGSC script

and then

chmod +x DOGSC

Now run the script with the syntax

DOGSC lat lon, e.g.,

DOGSC 55.368 -134.621

The result is the file gsc.list The first few lines of this file are

NDB      191.1411   145 19970101.0001 29991231.0000
MASB     225.3494   131 19990505.1919 29991231.0000
VIB      271.7930   149 20041123.1343 29991231.0000
DIB      278.7018   149 20040315.1942 29991231.0000
MOBC     301.9514   144 19960226.1956 29991231.0000
RUBB     303.6043   111 20120518.2140 29991231.0000
BNAB     332.2422   127 19990416.1834 29991231.0000
BNB      363.4351   148 19960226.1955 29991231.0000
DLBC     441.3487    37 19940928.2211 29991231.0000

The entries are station name, epicentral distances, azimuth, on_date and off_date.  Note that the station information was downloaded in September, 2012 and should be periodically  upgraded manually.

We are now ready to make the AutoDRM Request. Go to the following link:

CNDC AutoDRM data request page

The following pages show how the form is completed to get the SEED volume for the broadbands at Yellowknife.

When the list is complete, click on the "Submit" button.  The next page will be

submissted command


In a terminal window, enter the following command to get the UTC time for the time of submission:

rbh@bob:~$ date -u
Sun Jan 20 22:52:27 UTC 2013

Rather than wait for the Email message, go to the FTP site   ftp://ftp.seismo.nrcan.gc.ca/pub/autodrm/

ftp site

The filenames starting with CNDC are the SEED volumes.  Since the date command was just approximate, the file created at 10:51:00 PM is the one we want, e.g., 10:51 PM is 22:51 UTC.

You can use the browser to download, but I prefer to use the wget command to place this in the desired directory, e.g.,

wget ftp://ftp.seismo.nrcan.gc.ca/pub/autodrm/CNDC_20130120.225158


With LINUX and the Firefox browser I just drag the filename to the terminal window after I have typed wget, and then after the drag, I hit the Enter.

Now unpack in the Sac subdirectory, e.g.,

cd Sac
rdseed -f ../CNDC* -R -D -o 1
Since some stations may have EH, short period channels, remove those files, e.g.,  rm -fr *EH[ZNE]*


IRIS Waveserver