Digital Waveform Data for the Illinois Earthquake of
2008 04 18 09 37 00
This is page describes the digital data collected from the local
networks for the Mw=5.3 main event.
All data are contained in the gzip'd tar file ftp://ftp.eas.slu.edu/pub/rbh/20080418093700/20080418093700.tgz
This page discusses the files contained in the tar-ball.
1. Get the tar file
Either use anonymous ftp as follows
ftp ftp.eas.slu.edu
Username: anonymous
Password:
yourname@yourmail (your
Email address)
or
Enter ftp://ftp.eas.slu.edu/pub/rbh/20080418093700/20080418093700.tgz
on your browser
or use wget as follows
wget ftp://ftp.eas.slu.edu/pub/rbh/20080418093700/20080418093700.tgz
2. Unpack the tar file
gunzip 20080418093700.tgz
| tar xvf
-
(on windows you you may be able to do
this with winzip)
This will create a directory named 20080421053830.DATA
which contains raw data, processing scripts and response files.
3. Directory structure
The directory 20080421053830.DATA has the following directories
RAW.CERIBB
RAW.CMG5TD
RAW.EPISENSOR
RAW.FBA
RAW.SLUBB
a directory or responses
Resp
and the following processing
scripts
DOEVTACCCMG
DOEVTACCEPI
DOEVTVELCERIBB
DOEVTVELSLUBB
DOEVTIUBB
DOROTACC
DOROTVEL
The RAW directories contain the
original digital waveform data according to sensor and digitizer:
RAW.CERIBB
- Guralp CMG3-ESP broadband with Guralp DM24 digitizer
RAW.CMG5TD
- Guralp CMG5TD accelerometer
RAW.EPISENSOR
- Kinemetrics EpiSensor accelerometer with Quanterra Q330 digitizer
RAW.FBA -
Kinemetrics FBA-3 accelerometer with Quanterra Q380 digitizer
RAW.SLUBB -
Guralp CMG3-ESP or Nanometrics Trillium or Streckheisen STS-2 broadband
seismometer with Quanterra Q380/Q680 or Q330 digitizer
The Resp directory has channel specific pole-zero or generic pole zero
for all of the data streams.
The followin script convert the raw data to either ground velocity in
units of m/s or ground
acceleration in units of m/s/s.
Note
1: The scripts use the trace manipulation program gsac in the same manner as sac/sac2000.
Note
2: The waveforms are in sac binary format
in an INTEL byte order. The scripts use the program saccvt to ensure the correct byte
order for the machine that you are using.
Note
3: The programs gsac
and saccvt are part of
the Computer Programs in Seismology 3.30
package. By clicking on the link you can learn how to download this
free package of software for earthquake studies.
Run these scripts first!
DOEVTACCCMG - Create the
directory Acc if it does not exist. Place the event coordinates in the
Sac trace headers. Remove the instrument response to create ground
accleeration in units of m/s/s.
This script uses the same generic response for all CMG5-Td
accelerographs. These data are sampled at 50Hz. The results
are placed in the directory Acc.
DOEVTACCEP - Create the
directory Acc if it does not exist. Place the event
coordinates in the Sac trace headers. Remove the instrument response to
create ground accleeration in units of m/s/s. This script uses the
Episensor/Q330 response defined for each data channel. These data at
sampled at 100 Hz. These stations are at SIUC, OLIL and USIN. The
results are placed in the directory Acc.
DOEVTACCFBA - Create the
directory Acc if it does not exist. Place the
event
coordinates in the Sac trace headers. Remove the instrument response to
create ground accleeration in units of m/s/s. This script uses the
FBA-3/Q680 response defined for each data channel. These data at
sampled at 80 Hz. This sensor is adjacent to the broadband at MPH. The
results are placed in the directory Acc.
DOEVTVELSLUBB - Create the
directory Vel is it does not exist. Place the event coordinates in the
Sac trace headers. Remove the instrument response using a FREQLIMITS
0.002 0.004 100 200 for stability at low frequencies. The output
will be ground velocity in m/s
from 0.004 Hz to a little less than the Nyquist frequency. The
script uses the pole-zero response obtained from the dataless seed for
the stations. The results are placed in the directory Vel. The sample
rate are 20/40/80 and 100 Hz depending on the channel.
DOEVTVELIUBB - Create the
directory Vel is it does not exist. Place the event
coordinates in the Sac trace headers. Remove the instrument response
using a FREQLIMITS 0.002 0.004 100 200 for stability at low
frequencies. The output will be ground velocity in m/s from 0.004 Hz
to a little less than the Nyquist frequency. The script uses the
pole-zero response obtained from the dataless seed for the stations.
The results are placed in
the directory Vel. The sample rate is 20 Hz.
DOEVTVELCERIBB - Create the
directory Vel is it does not exist. Place the event
coordinates in the Sac trace headers. Remove the instrument response
using a FREQLIMITS 0.002 0.004 100 200 for stability at low
frequencies. The output will be ground velocity in m/s from 0.004 Hz
to a little less than the Nyquist frequency. The script uses the
pole-zero response obtained from the dataless seed for the stations.
The results are placed in
the directory Vel. The sample rate is 100 Hz.
Now Run these two scripts!
DOROTVEL - Create the
directory Vel.Rot. High pass fitler the traces with a two pole
Butterworth filter at 0.002 Hz for stability. Rotate the traces to
vertical, radial and transverse components. Rename the traces to
be of the form StaNetLocCom, e.g., SLMNMBHZ
DOROTACC
- Create
the directory Acc.Rot. High pass fitler the traces with a two
pole
Butterworth filter at 0.02 Hz for stability. Rotate the traces to
vertical, radial and transverse components. Rename the traces to
be of
the form StaNetLocCom, e.g., SLMNMHNZ