Global geodynamic changes induced by all major earthquakes, 1976–2015

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Title:	Global geodynamic changes induced by all major earthquakes, 1976–2015
Authors:	趙丰;Chao, Benjamin F.;Ding, Hao
Contributors:	地球科學學院地球科學學系
Keywords:	Centroids;coseismic effect;Drift;Earth;Earth gravitation;Earth rotation;Earth surface;Earth's evolution;Earth's rotation variations;Earthquakes;Energy;Evolution;Excitation;Geodynamics;Geophysics;global geodynamics;Gravitational effects;Gravitational instability;Gravity;Inertia;Instability;major earthquakes;Mathematical analysis;Moments of inertia;Movement;Parameters;Planetary evolution;Plate tectonics;Rotation;Seismic activity;Seismology;Statistical analysis;Statistics;Tensors;Thrust;Trends
Date:	2016-12-01
Issue Date:	2026-04-23 11:34:34 (UTC+8)
Publisher:	Wiley-Blackwell;Washington: Blackwell Publishing Ltd
Abstract:	摘要： Using normal‐mode summations we calculate the coseismic changes in a suite of global geodynamic quantities produced by all the 43,304 major earthquakes that occurred during 1976–2015 from the Global Centroid Moment Tensor catalogue. We calculate changes for the Earth's inertia tensor elements and the ensuing Earth's rotation variations, as well as the monopolar changes of the volume ΔV(r), the total moment of inertia ΔT(r), and the gravitational energy ΔEg(r) as functions of the radius inside the Earth. The cumulative geodynamic changes are found to have strong statistical trends that are continuing from the past and further strengthened in recent years. Statistical analyses indicate that the thrust‐faulting earthquakes are predominantly responsible for these trends, as they are the dominant type overshadowing the normal‐faulting earthquakes that tend to produce the opposite effects. In particular, we report that the polar motion excitations due to the few greatest earthquakes since 2004 have facilitated the abrupt turn of the pole path observed during these years. For the monopolar parameters, we find an overall shrinkage in Earth's volume V(r) internally but an expansion near Earth's surface. The ensuing gravitational instability cannot be sustained over time and will be reversed by aseismic and interseismic deformations. The ΔT(r) and ΔEg(r) also exhibit trends where the coseismic action of earthquakes collectively makes the Earth more compact and dissipate a great amount of gravitational energy. Although aseismic effects are not addressed here, these coseismic trends are in keeping with the long‐term physical evolution of the Earth. Key Points Coseismic geodynamic changes and cumulative trends calculated for 43,304 major earthquakes 1976‐2015 Strong trends (dominated by thrust faultings) in monopolar changes ΔV, ΔT, and ΔEg are consistent with Earth's evolution Polar motion excitation by recent large earthquakes contributes significantly to observed polar drift 出版者： Washington: Blackwell Publishing Ltd 出版日期： 2016-12 出處： Journal of geophysical research. Solid earth, 2016-12, Vol.121 (12), p.8987-8999 資源來源： Wiley Online Library All Journals 版權： 2016. American Geophysical Union. All Rights Reserved. 識別號： ISSN: 2169-9313 識別號： EISSN: 2169-9356 識別號： DOI: 10.1002/2016JB013161
Appears in Collections:	[Department of Earth Sciences ] journal & Dissertation

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