DigitSeis: software to extract time series from analogue seismograms

Abstract A vast amount of analogue seismograms recorded between the end nineteenth century and late twentieth are often inaccessible for seismological research since they not available as digital time series. This manuscript describes freely software, DigitSeis, that takes a image an seismic record returns waveforms either function their x-y position on or time–amplitude information. The overall structure approach software provided along with how have evolved over different versions. effectiveness is demonstrated three examples. first example long-period east–west seismogram at Harvard Seismographic Observatory photographic paper in May 1938, which contains signals associated magnitude 7.7 earthquake occurred off coast Northern Ibaraki, Japan. second analysis 35-mm microfilm copy short-period vertical Tucson, Arizona, July 16, 1945, shows blast from nuclear bomb detonation. final uses 70 mm microfiche north–south College, Alaska December 1966, pair earthquakes nearly identical waveforms. is, by no means, perfect, discussion its limitations such compatibility pen- Develocorder-type included, well comments about challenges incorporating machine learning into digitization process.