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Abstract # S51B-1013 The Rocky Mountain Front PASSCAL experiment was a deployment of 33 broadband seismic stations spread across the state of Colorado. The stations collected continuous data recording at 10 samples per second and were spaced approximately 75km apart. Acquired in 1992, approximately six months of data from these stations was used to determine local earthquake event epicenters and magnitudes. The initial purpose of the Rocky Mountain Front deployment was to provide data for teleseismic imaging, however the dataset is also valuable for observing local earthquake events in Colorado for this limited time period. UNIX-based Antelope dbpick and dbloc2 programs were used to pick P and S-arrivals and locate hypocenters using a 1-D velocity model for the Colorado crust. Local event magnitude was determined using an automated magnitude duration algorithm. The majority of the events were determined to be mining blasts, based upon their epicentral location, the time of day the events occurred (usually the afternoon), and their waveform. Generally, mining blasts tend to have more emergent waveforms than an impulsive seismic event. An event catalog was created of Colorado seismicity for May-December 1992. Based upon a magnitude frequency curve, it was determined that the sensitivity of the Rocky Mountain Front array was complete for events of magnitude 3 and greater. This was compared to magnitude frequency curves of the National Earthquake Information Center (NEIC) catalog from 1992 to present, and the Front Range network (MGC) catalog from 1983 to 1993. Because of the regular spacing and spread of our network, it offers greater sensitivity in Colorado than the sizeable NEIC array and a greater reach than the concentrated MGC array. The new Rocky Mountain Front catalog consists of 24 probable earthquake events during the approximate six-month period in 1992. Further sampling of Colorado seismicity will be possible through the upcoming EarthScope USArray deployment. |