Open AccessSpectral Content of Teleseismic P ‐Waves Recorded at the Hagfors Observatory
Author(s) -
Israelson H.
Publication year - 1971
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1971.tb02332.x
Subject(s) - observatory , ridge , seismology , epicenter , geology , magnitude (astronomy) , azimuth , range (aeronautics) , spectral line , geodesy , physics , astrophysics , paleontology , astronomy , materials science , composite material
Summary 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.