Ocean loading effects on stress at near shore plate boundary fault systems

Citation:
Luttrell, K, Sandwell D.  2010.  Ocean loading effects on stress at near shore plate boundary fault systems. Journal of Geophysical Research-Solid Earth. 115

Date Published:

Aug

Keywords:

california, cascadia subduction zone, dislocation model, earthquakes, new-zealand, san-andreas fault, sea-level change, seismicity, slip rates, surface

Abstract:

Changes in eustatic sea level since the Last Glacial Maximum create a differential load across coastlines globally. The resulting plate bending in response to this load alters the state of stress within the lithosphere within a half flexural wavelength of the coast. We calculate the perturbation to the total stress tensor due to ocean loading in coastal regions. Our stress calculation is fully 3-D and makes use of a semianalytic model to efficiently calculate stresses within a thick elastic plate overlying a viscoelastic or fluid half-space. The 3-D stress perturbation is resolved into normal and shear stresses on plate boundary fault planes of known orientation so that Coulomb stress perturbations can be calculated. In the absence of complete paleoseismic indicators that span the time since the Last Glacial Maximum, we investigate the possibility that the seismic cycle of coastal plate boundary faults was affected by stress perturbations due to the change in sea level. Coulomb stress on onshore transform faults, such as the San Andreas and Alpine faults, is increased by up to 1-1.5 MPa, respectively, promoting failure primarily through a reduction in normal stress. These stress perturbations may perceptibly alter the seismic cycle of major plate boundary faults, but such effects are more likely to be observed on nearby secondary faults with a lower tectonic stress accumulation rate. In the specific instance of rapid sea level rise at the Black Sea, the seismic cycle of the nearby North Anatolian fault was likely significantly advanced.

Notes:

n/a

Website

DOI:

10.1029/2009jb006541

Scripps Publication ID:

B08411