Correlations between earthquake magnitude and early features of rupture
in a global dataset
Abstract
It remains uncertain whether an earthquake ”knows” its final magnitude
part-way through its rupture. Several studies have found that early
features of rupture can constrain final earthquake magnitude, but many
of these have considered datasets with fewer than 100 earthquakes in
order to reduce extraneous sources of variability. We consider a larger,
but less carefully curated dataset. We calculate four parameters of the
early portions of seismograms using $>$4000 earthquakes
from around the world; we simply accept the scatter inherent in such a
range of events. Despite this scatter, we find that on average larger
earthquakes have distinct features in their early stages: they have
longer predominant and average periods, release more energy, and reach
higher maximum moment rates. The differences between small and large
earthquakes persist even when we consider short measurement windows less
than 1/3 of the earthquake duration. These results further evidence that
there are physical differences between the early stages of large and
small earthquakes. These, and further observations, could help us better
understand how local stresses and frictional weakening drive earthquake
rupture.