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Earthquake Contacts: 24 Hour Earthquake Reporting Hotline: 1-855-QuakeOH 1-855-(782-5364) Media Inquiries Quake Info Center: Michael C. Hansen Phone: (740) 548-5979 Fax: (614) 447-1918 E-mail Web Page
The time interval between successive crests in a sinusoidal wave train; the period is the inverse of the frequency of a cyclic event.
Bolt, B. A., 1993, Earthquakes: W. H. Freeman and Co., New York, p.311.