Open AccessHigh‐ Q Overtone Modes of the Earth
Author(s) -
Dratler J.,
Farrell W. E.,
Block B.,
Gilbert F.
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.tb01832.x
Subject(s) - overtone , multiplet , oscillation (cell signaling) , physics , mode (computer interface) , normal mode , noise (video) , computational physics , earth (classical element) , atomic physics , geology , spectral line , acoustics , chemistry , quantum mechanics , astronomy , vibration , image (mathematics) , artificial intelligence , computer science , operating system , biochemistry
Summary Overtone modes of free oscillation of the Earth have been observed with two instruments at two separate locations after the Colombian earthquake of July 31, 1970. Certain overtones persisted with a signal‐to‐noise ratio as high as 20 db for 50 hr after the origin time. Some spheroidal radial overtones (modes of type n S 0 ) were found to have Q 's near 1000, about three times the typical Q of a fundamental mode ( 0 S I ). Multiplet centre frequencies and Q 's were measured for several overtones, with good agreement between the two stations.