Maryland Department of Natural Resources

Garrett College Station (GCMD) Spectrogram Record

April   1 ,  2004  (UTC),
vertical ⁄ global  motion

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 Other views: 
    Motion:
vertical 
north/south 
east/west 
    Scope:
local 
global 
 

 

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*Records are available from Jun. 26, 2018
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Use the calendar to select another day or month to view. Click on a day box to view that day's spectrogram record. Use the << and >> buttons next to the "Month, Year" title bar to skip forward or backward one month. Also, use the dropdown menus at the bottom of the calendar to select other months and years, then click the "view" button.


In the "Other Views" box above, select "local" or "global" radio buttons in the "Scope" column to view local seismic events or global events.


  • Local:  Small, close-by seismic events. Locally generated seismic signals tend to be higher frequency and lower amplitude than large, distant events.  There is more noise in the local display due to traffic, wind, etc.

  • Global:  Large, distant seismic events. Major, more distant seismic events generate lower frequency and higher amplitude seismic signals, which obscure locally generated signals.

When you select "local" you are viewing data which has had the lower frequencies filtered out. When you select "global" you are viewing unfiltered data. You may also select a motion vector to view in the "Motion", column. For more information about this helicorder record see the helicorder help page.


To see a listing of recent earthquake you might see on the helicorder records view:

You can also use the USGS "Earthquake Travel Time Information and Calculator" page to estimate the arrival times of seismic waves from an epicenter to the Garrett College seismometer. Use the following coodinates (decimal degrees) for the Garrett College area:


latitude       39.5624
longitude   -79.3383