Abstract
The Slow-Slip hypothesis is postulated on two observations – existence
of tectonic tremors and their spatio-temporal correlation with anomalous
‘slow’ reversals in horizontal geodetic measurements. The above
observations have led geoscientists to believe that the down-dip portion
of the plate interface is slowly shearing and releases energy gradually
in the form of tremor. However, numerous observations and scientific
findings are poorly explained by the Slow-Slip hypothesis. Here, we show
that periodic seismic activity and geodetic changes, result from the
episodic buckling of the overriding continental crust and its rapid
collapse on the subducting oceanic slab. According to the Episodic
Buckling and Collapse hypothesis, geodetic measurements, previously
inferred as slow slip, are the surficial expressions of slowly-evolving
buckling and rapid collapse of the overriding plate, while tremor swarms
result from the striking of the collapsing overriding plate on the
subducting slab (as opposed to slipping or shearing). All existing
scientific observations and findings are resonably explained by the
proposed model. In addition, we provide additional evidence in the form
of numerical studies of static deformation and analysis of vertical and
horizontal GPS measurements in Cascadia and Alaska. We also show how
subduction zones all around the world exhibit a beautiful relationship
between the tremor interval and the slenderness ratio of the overriding
plate – a relationship that closely resembles that between critical
stress and slenderness ratio that is characteristic of Euler’s buckling.