Processing of seismic data from an automatic digital recorder

Data from a three-component, long-period seismometer system is recorded in digital form on magnetic tape by a device which has been described by Miller. Preliminary editing and processing is performed to select events of interest from the 24-hour tapes and place them on a library tape that is compatible with a computer. Emphasis is placed on location, correction, and flagging of errors that occur during the recording and editing process. Processing routines developed include: correction for seismometer response, orbital motion functions, energy computation, band pass filtering for mode separation, etc. The dynamic range of the system is 86 db and the response is adequate over the range .02 to 2.0 cps. For the purpose of detailed analysis, digital records from this system are superior to paper records from any of the existing seismographs in use at this laboratory. The main disadvantage of data in this form is the difficulty of inspecting signals by eye in order to make preliminary interpretations.