THE AS1 AND VIRGINIA EARTHQUAKE

On August 23, 2011 at 17:51:04 UTC a 5.8 magnitude earthquake struck in the central Virginia seismic zone. The earthquake was felt from Maine to Georgia along the Eastern Seaboard and detected by the AS1 seismograph at SUNY Potsdam. In the days following the main shock, two aftershocks of magnitude 4.5 and 3.0 were recorded.

The AS1 is a simple inexpensive ($600.00) seismograph capable of recording distant and local earthquakes. The epicenter of the Virginia earthquake was at a distance of 784km or 7° yet excellent records of the earthquake were attained. Travel time curves for the Eastern United States by Nuttli were used to analysize the seismogram to identify P_n, P⁺, Pg, Sn, S⁺, and Lg. Magnitude of the earthquake was determined by using Nuttli formula for Eastern United States mbLg=Log A/T + 1.66LogD + 3.3. The free AmaSeis software calculated the Fourier transform of the earthquake indicating maximum energy associated with .9 Hz frequency. The record of the earthquake was also used to create student exercises on seismogram interpretation. The inexpensive AS1 proved to be an excellent seismograph for recording earthquakes for student use and research.