Lateral change of in-plate stress and seismicity along the southern
Mariana trench
Abstract
Lithospheric flexure at subduction zones is a major contributor to
induce outer rise earthquakes. Here, we modeled the bending deformation
of the subducting plate at the southern Mariana using a 3-D plate
flexural model. Intraplate stresses were investigated, with the
along-strike variable boundary loadings. In order to match the
observations of plate geometry, boundary vertical loading near the
Challenger Deep has to be set twice of that in other areas. We also
compared results between 2-D and 3-D models and found that the
difference on estimating plate stress can exceed 20% when there is an
along-strike variation in plate bending. Finally, we found that the
sharp lateral variation in the σ and the σ corresponded to an outer rise
earthquake cluster at the southern Mariana subduction zone, indicating
that along-strike variation in σ and σ may be a significant mechanism to
cause non-uniform distribution of outer rise earthquakes.