We investigate upper plate stressing during the earthquake cycle in
a subduction segment, using 3D elastic models to address the effects of
strongly heterogeneous coupling along- strike of the interplate interface.
We show how heterogeneity controls the locations and mechanisms of
seismicity in the upper plate. Oblique subduction segments, two from
the Aleutians (Andreanof Islands 1986 and Rat Islands 1965) and one from
Indonesia (Biak 1996) are studied. All examples of upper plate seismicity
from the Aleutians represent events occurring toward the beginning of a
new cycle, while in Biak, Indonesia, the examined events occur both towards
the end of one cycle and the beginning of the next. In the majority
of cases studied the location and mode of the upper plate seismicity is
consistent with space- and time-dependent stressing as predicted by modeling.
This confirms earlier observations that seismicity in the vicinity of large/great
subduction earthquakes (towards the outer rise, at intermediate depth,
and now in the upper plate) depends, in an interpretable manner, on the
stage in the earthquake cycle as well as on distribution of coupling along
the interplate interface.