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The OhioSeis digital seismographs produce research-quality seismograms. These seismograms are available in real-time via the web server that is part of MacOS 8. SeismoGraf writes: (1) binary "s" files into the private data directories (i.e., folders), and (2) ASCII "a" files into the public data directories within the "Web Pages" directory.
| "s" |
files are in compressed binary format that can only be read by the SeismoView program.
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| "a" |
files are plain text ASCII files that can be read by SeismoView, but they can also be read by text editor and spreadsheet programs.
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The "a" files conforms to the "AH" format, a seismological standard format originally introduced by Lamont Geological Observatory, and now recognized by the IRIS Data Center. Seismologists should be able to directly read these "a" files and properly interpret all the header information, including the instrument response.
Location and format of the various data files:
- Within the "xxxx_Station" folder (private to the xxxx station), there are "Data" and "DayView" folders. Within the Data folder, SeismoGraf creates folders for each day, and then creates "s" files within these folders, each file contains the seismogram for one hour. The last number in the file name gives the hour.
For example, a seismic event arrived at station "xxxx" on Jan. 4, 1999, at about 17 hour 30 minute.
- Starting from "xxxx_station" folder, double-click on the "Data" folder.
Then double-click on the "1999.01.04" folder. If the station was running for the entire day there will be 24 "s" files in the folder.
Locate the file with filename "sXXXXZIP1999.01.04.17". This file contains the seismogram that runs from 17 hour 0 min to 17 hour 59 min.
Double-click on the file icon, SeismoView will then display this seismogram. Use the plot controls in SeismoView to turn up the plot gain, zoom out the time axis, and scroll through the minute range of interest.
- Within the "xxxx_Station" folder (private to the xxxx station), there are "Data" and "DayView" folders. Within the "DayView" folder, SeismoGraf creates a "dv" file for each day. Recall that "DayView" is the digital equivalent of seeing an entire 24 hour recording in one graphics window that fits on the screen of your computer. When you ask the question: "I wonder if there was an earthquake somewhere in the world yesterday?", DayView provides a quick answer. Starting from your "xxxx_station" folder, you double-click on the "DayView" folder, then you double-click on, e.g., the "1999.01.04.xxxx" file icon. SeismoView will then display this highly condensed seismogram in a special DayView graphics window that shows 24 hours. Use the DayView plot gain sub-menu in SeismoView to turn up the plot gain, then look for "bumps" that are above the basic background noise level. These bumps might be earthquakes, though isolated spikes are usually just local noise. To know for sure, you then go look at the seismogram file for that hour.
- Within the "Web Pages" folder (available to others), there are "Data" and "DayView" folders. Within the Data folder, SeismoGraf creates folders for each day, and then creates "a" files within these folders, each file contains the seismogram. The names for all these files are the same as for the private "s" files, EXCEPT that these filenames start with "a". This identifies these as public SeismoGraf files written in ASCII plain text.
When someone uses a web browser to access to your station, they can click on the link to the "Data" folder, they will then see all the folders for each day, and they can click on the day of interest to see all the individual hour files. If they click on a particular file, then the web browser will show that text in its window; but the web browser may complain that the text file is too large to show. This is not a problem. Just go to the browser's menu to "Save as...", it is best to use the default name for the file (same name as the original "a" file), then the remote web browser will essentially copy that file from your Macintosh to their computer (which can be a Mac, a PC, or a UNIX computer). They now have the ASCII file on their computer.
If the remote user has a Macintosh (of any type) and a copy of SeismoView (version 98.12) on their Mac, they can use SeismoView to display the seismogram. To do so, you must first start up SeismoView, then use the "File" menu to highlight "Open SeismGraf file...". Use the standard Macintosh file finder dialog to open the "a" file. After SeismoView reads in the "a" file, the display and plot options are the same as if you had read in an "s" file for the same seismogram.
- Within the "Web Pages" folder (available to others), there are "Data" and "DayView" folders. Within the DayView folder, SeismoGraf creates "a" files for each day. The names for all these files are the same as for the private "dv" files, EXCEPT that these filenames start with "a". This identifies these as public DayView files written in ASCII plain text; they are also in "AH" format. These "a" DayView files can be downloaded from another xxxx Seismic station, over the internet, just like the private seismogram files. The only difference is to them in SeismoView, choose the "Open DayView Files..." menu option, then it is opened into the DayView graphics window.
Last update March 10, 2003
Ohio Seismic Network http://www.dnr.state.oh.us/OhioSeis
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