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The relationship between the instantaneous velocity field and the rate of moment release in the lithosphere

Geophysical Journal International

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DOI: 10.1046/j.1365-246X.2003.01924.x

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Abstract

Instantaneous velocity gradients within the continental lithosphere are often related to the tectonic driving forces. This relationship is direct if the forces are secular, as for the case of loading of a locked section of a subduction interface by the downgoing plate. If the forces are static, as for the case of lateral variations in gravitational potential energy, then velocity gradients can be produced only if the lithosphere has, on average, zero strength. The static force model may be related to the long-term velocity field but not the instantaneous velocity field (typically measured geodetically over a period of several years) because over short time intervals the upper lithosphere behaves elastically. In order to describe both the short- and long-term behaviour of an (elastic) lithosphere-(viscoelastic) asthenosphere system in a self-consistent manner, I construct a deformation model termed the expected interseismic velocity (EIV) model. Assuming that the lithosphere is populated with faults that rupture continually, each with a definite mean recurrence time, and that the Earth is well approximated as a linear elastic-viscoelastic coupled system, I derive a simple relationship between the instantaneous velocity field and the average rate of moment release in the lithosphere. Examples with synthetic fault networks demonstrate that velocity gradients in actively deforming regions may to a large extent be the product of compounded viscoelastic relaxation from past earthquakes on hundreds of faults distributed over large (??? 106 km2) areas.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The relationship between the instantaneous velocity field and the rate of moment release in the lithosphere
Series title:
Geophysical Journal International
DOI:
10.1046/j.1365-246X.2003.01924.x
Volume
153
Issue:
3
Year Published:
2003
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geophysical Journal International
First page:
595
Last page:
608
Number of Pages:
14