Viscoelastic-cycle model of interseismic deformation in the northwestern United States
Geophysical Journal International
By: F. F. Pollitz, Patricia McCrory, Doug Wilson, Jerry Svarc, Christine Puskas, and Robert B. Smith
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Abstract
We apply a viscoelastic cycle model to a compilation of GPS velocity fields in order to address the kinematics of deformation in the northwestern United States. A viscoelastic cycle model accounts for time-dependent deformation following large crustal earthquakes and is an alternative to block models for explaining the interseismic crustal velocity field. Building on the approach taken in Pollitz et al., we construct a deformation model for the entire western United States-based on combined fault slip and distributed deformation-and focus on the implications for the Mendocino triple junction (MTJ), Cascadia megathrust, and western Washington. We find significant partitioning between strike-slip and dip-slip motion near the MTJ as the tectonic environment shifts from northwest-directed shear along the San Andreas fault system to east-west convergence along the Juan de Fuca Plate. By better accounting for the budget of aseismic and seismic slip along the Cascadia subduction interface in conjunction with an assumed rheology, we revise a previous model of slip for the M~ 9 1700 Cascadia earthquake. In western Washington, we infer slip rates on a number of strike-slip and dip-slip faults that accommodate northward convergence of the Oregon Coast block and northwestward convergence of the Juan de Fuca Plate. Lateral variations in first order mechanical properties (e.g. mantle viscosity, vertically averaged rigidity) explain, to a large extent, crustal strain that cannot be rationalized with cyclic deformation on a laterally homogeneous viscoelastic structure. Our analysis also shows that present crustal deformation measurements, particularly with the addition of the Plate Boundary Observatory, can constrain such lateral variations.
Suggested Citation
Pollitz, F., McCrory, P., Wilson, D., Svarc, J., Puskas, C., Smith, R.B., 2010, Viscoelastic-cycle model of interseismic deformation in the northwestern United States: Geophysical Journal International, v. 181, no. 2, p. 665-696, https://doi.org/10.1111/j.1365-246X.2010.04546.x.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Viscoelastic-cycle model of interseismic deformation in the northwestern United States |
| Series title | Geophysical Journal International |
| DOI | 10.1111/j.1365-246X.2010.04546.x |
| Volume | 181 |
| Issue | 2 |
| Year Published | 2010 |
| Language | English |
| Publisher | Wiley |
| Publisher location | Hoboken, NJ |
| Contributing office(s) | Earthquake Science Center |
| Description | 32 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Geophysical Journal International |
| First page | 665 |
| Last page | 696 |
| Country | United States |