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Toroidal splitting observations from the Great 1994 Bolivia and Kuril Islands Earthquakes
Author(s) -
Tromp Jeroen,
Zanzerkia Eva
Publication year - 1995
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/95gl01810
Subject(s) - toroid , physics , mantle (geology) , geology , seismology , geophysics , plasma , nuclear physics
The June 9, 1994, Bolivia earthquake and the October 4, 1994, Kuril Islands earthquake provide a unique opportunity for a splitting analysis of the Earth's long‐period toroidal free oscillations. We present toroidal splitting observations for the 6 fundamental modes 0 T 4 , 0 T 5 , 0 T 6 , 0 T 7 , 0 T 8 , and 0 T 9 , and for the 5 first overtones 1 T 1 , 1 T 2 , 1 T 3 , 1 T 4 and 1 T 6 . The first identification of mode 1 T 1 is made possible by simultaneously fitting the multiplets 1 T 1 and 0 T 7 . The observed splitting is reasonably well explained by current shear velocity models of the mantle. Our analysis yields new estimates of the center frequencies and quality factors of these 11 toroidal modes.