Open AccessIdentification of Free Oscillation Spectral Peaks for 1970 July 31, Colombian Deep Shock using the Excitation Criterion
Author(s) -
Mendiguren Jorge A.
Publication year - 1973
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.1973.tb03422.x
Subject(s) - aftershock , excitation , shock (circulatory) , physics , oscillation (cell signaling) , range (aeronautics) , standard deviation , excited state , geology , computational physics , geodesy , atomic physics , seismology , mathematics , statistics , materials science , quantum mechanics , chemistry , medicine , biochemistry , composite material
Summary The excitation criterion was applied to identify spectral peaks of free oscillations excited by the Colombian deep shock of 1970 July 31. About 160 new overtones were identified. They range from 1 T to 3 T torsional modes and from 1 S to 6 S spheroidal modes. Some of the modes identified have periods below 90 s. The standard deviation of the measured eigen‐ periods is in general smaller than 0.1%. Comparison of 0 S and 0 T eigenperiods measured for the Alaskan (1964) and Colombian shocks shows a systematic difference. The difference is larger than the error of the measurement, and this indicates that the average eigenfrequencies measured for each event are biased by the epicentre location. The effect of lateral heterogeneities of the Earth, aftershocks, and the choice of source and Earth model when using the excitation criterion are discussed in detail.