Open AccessChanges in the Earth's rotational energy induced by earthquakes
Author(s) -
Chao Benjamin Fong,
Gross Richard S.
Publication year - 1995
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1995.tb06836.x
Subject(s) - polar motion , rotation (mathematics) , polar , kinetic energy , rotation around a fixed axis , rotational energy , geology , energy (signal processing) , earth's rotation , physics , earth (classical element) , excitation , geodesy , seismology , geophysics , classical mechanics , geometry , mathematics , quantum mechanics , astronomy , mathematical physics
SUMMARY The kinetic energy of the Earth's rotation can be separated into two parts: the spin energy and the polar‐motion energy. Here we derive rigorous formulae for their changes, where the polar‐motion energy change is related to the polar‐motion excitation function via a treatment of reference frames. The formulae are then used to compute co‐seismic energy changes induced by the static displacement field produced in an idealized earth model by a total of 11015 major earthquakes that occurred during the period 1977 to 1993. An extremely strong statistic is found for the earthquakes' tendency to increase the Earth's spin energy; the rate during 1977 to 1993 was +6.7 GW, about the same as the total seismic‐wave energy release. The corresponding polar‐motion energy changes are 10 −6 times smaller and had no detectable statistical tendency in their signs.