Fortran Specialist Group

GEDESS: A Series of Computer Programs (FORTRAN) for Deriving Information at Selected Recording Sites for Signals from Known (Seismic) Hypocentres

GEDESS is a predictor! GEDESS takes seismic hypocentre information, predicts the arrival times of seismic phases at selected seismic recording stations, and generates a listing of information.

The GEDESS listing is printed in approximately two halves, side by side on the page. The left hand side is the listing of earthquakes, usually in chronological order with as much information as given in the hypocentre file, including event numbers, origin time, latitude and longitude, depth, magnitudes, some statistics, and the region number and name. The right hand side is station data in a given order with the seismic station code, the predicted arrival times of the first seismic phases P or PKP, the phase velocity of P or PKP, and an estimate of the arrival time of the seismic surface waves at a given period. Also computed are the angular values of distance, azimuth, and back-bearing (back-azimuth), all given in degrees from the epicentre to the station. A heading is printed at the top of a new page for each new day and the tables used are printed for each new year.

The GEDESS listing was produced monthly in various forms from January 1963 to December 1997 and then weekly until December 2003; a total of 41 years. The original computer printout for January 1963 is in the BGS archives and the last printout in December 2003 was produced as a booklet. Over the years microfiche was produced as well as computer printout. These forms ceased in 1997; the last printout is also in the BGS archives. The microfiche is available for January 1964 to October 1967. From January 1998 to December 2003 the GEDESS listing was produced as a weekly booklet and was available within six to eight weeks of the first date of the booklet. The booklet listing was also available via the Internet.

GEDESS was the 'brain-child' of T.L. van Raalte when he was at Blacknest and the original FORTRAN program was written by Maureen Bell. John Young continued the development of GEDESS to the extent of 8 different programs with up to 12 versions of each. GEDESS ceased to be of use with the introduction of the Internet and users being able to access hypocentre information from the Web. When the format of the hypocentre information was changed in January 2004 it was decided it was time to send GEDESS to the Blacknest archive.

For a fuller description of GEDESS, but now an old reference, see:
AWRE REPORT No. O54/68. GEDESS: A Series of Computer Programs for Deriving Information at Selected Recording Sites, for Signals from Known Hypocentres. J.B. Young and P.G. Gibbs.

For a full description of the region numbers and names see:
Physics of the Earth and Planetary Interiors [PEPI] (1996) 223-297. The Flinn-Engdahl Regionalisation Scheme: the 1995 revision. J.B.Young, B.W. Presgrave, H Aichele, D.A. Wiens, E.A. Flinn.

John Young.
Fortran Golden Jubilee Meeting.
25th January 2007.

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