Spectral Content of Teleseismic P-Waves Recorded at the Hagfors Observatory

• Published in: Geophysical Journal International
• Main Author: Israelson, H.
• Format: Text
• Language: English
• Published: Oxford University Press 1971
• Subjects: Articles; Hagfors; Pacific; North Atlantic
• Online Access: http://gji.oxfordjournals.org/cgi/content/short/25/1-3/89; https://doi.org/10.1111/j.1365-246X.1971.tb02332.x

Bandpass spectra of short period P -waves recorded at the Hagfors Observatory in Sweden from some 200 seismic events at distances from 20 to 100 degrees have been analysed. Attempts at estimating significant differences between spectra of signals originating from the same epicentre region show that an increase of the focal depth from 40 km to 80 km can shift the spectral content substantially towards higher frequencies. The size effect within a range of one magnitude unit, however, is not very strongly shown. An outline of the large-scale regional variations of the spectral characteristics for shallow focus events shows a systematic azimuthal difference. Events in geographical regions such as the Northeast Pacific, the North Atlantic Ridge and South America appear to radiate less high frequency energy than North-west Pacific and Central Asian events.