  High-frequency ground motion simulations pose a grand challenge in
computational seismology. Two main factors drive this challenge. First, to
account for higher frequencies, we have to extend our numerical models, e.g.,
by considering anelasticity, or by including mountain topography. Second, even
if we were able to keep our models unchanged, simply doubling the frequency
content of a seismic wave propagation solver requires a sixteen-fold increase
in computational resources due to the used four-dimensional space-time domains.
  This work presents the Extreme Scale Discontinuous Galerkin Environment
(EDGE) in the context of high-frequency ground motion simulations. Our
presented enhancements cover the entire spectrum of the unstructured finite
element solver. This includes the incorporation of anelasticity, the
introduction of a next-generation clustered local time stepping scheme, and the
introduction of a completely revised communication scheme. We close the
modeling and simulation loop by presenting our new and rich preprocessing,
which drives the high problem-awareness and numerical efficiency of the core
solver.
  In summary, the presented work allows us to conduct large scale
high-frequency ground motion simulations efficiently, routinely and
conveniently. The soundness of our work is underlined by a set of
high-frequency verification runs using a realistic setting. We conclude the
presentation by studying EDGE's combined algorithmic and computational
efficiency in a demanding setup of the 2014 Mw 5.1 La Habra earthquake. Our
results are compelling and show an improved time-to-solution by over 10x while
scaling strongly from 256 to 1,536 nodes of the Frontera supercomputer with a
parallel efficiency of over 95%.
