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This felt earthquake had an epicenter about 25 miles NW of Ponca City. It was felt widely in Grant, Garfield, and KAY Counties. No damage or injuries are expected. The above seismogram is earth acceleration recorded from three Geotech BB-13 seismometers in the walk-in vault at Leonard. The signals were digitized 40 times per second. P waves and S waves from the earthquake are labelled. The seismogram labelled "bz" is vertical earth acceleration. The seismogram marked "br" is horizontal earth acceleration in a line to the epicenter and away from the epicenter (r=radial). "bt" is horizontal earth acceleration at right angles (t=transverse) to the direction of the epicenter. The horizontal seismometers are lined North-South, and East-West, but simple trigonometry in the "Geotool" seismic analysis package combines and rotates the horizontal traces. To help OGS map the felt effects of this earthquake, would anyone who felt and/or heard the earthquake at 11:41AM OCT30 please write to us? Please tell us where you were, and what you experienced in as much detail as possible. Mail to: Oklahoma Geological Survey Box 8 Leonard, OK 74043 or to: Earthquake Leonard, OK 74043 or E-mail to: jimlawson@okgeosurvey1.gov (You can't mail directly from this web page).