Understanding earthquakes and quantifying seismic hazard require translating models of source processes into computer simulations and validating those simulations against data to gain confidence in the underlying model. Alice-Agnes Gabriel has emerged as a world leader who is working at the very forefront of this important endeavor.

Alice has pioneered the workflows to perform, if necessary in the immediate aftermath of an earthquake, sophisticated 3D earthquake (and tsunami) simulations. These dynamic source models go well beyond the widely used kinematic source models of fault slip to consider the complex combination of stress and friction conditions required to reproduce the observed behavior. She calibrates and validates the models by comparison with strong motion, crustal deformation and teleseismic waveform data. The collective application of this modeling approach to many recent events — including the 1992 Landers, 2004 Sumatra, 2016 Kaikōura, 2019 Ridgecrest and 2023 Kahramanmaraş earthquakes — provides important insights into earthquake dynamics, strong ground motion and wave propagation. Her work underscores how stress conditions must be just right for ruptures to navigate through complex fault networks and grow into large earthquakes.

To achieve this, Alice and her students developed and made available to the earthquake science community the most powerful open-source dynamic rupture and seismic wave propagation code (SeisSol). This ambitious undertaking involved deep collaborations with applied mathematicians and computer scientists. It also required petascale computing to resolve the small-scale processes within the rupture front and damage zone that are critical to representing fault failure, topography and material heterogeneity that scatter seismic waves, and inelastic yielding processes — all in 3D for hazard-scale earthquakes. A growing number of groups around the world are using SeisSol because of its capabilities and excellent documentation, a testament to Alice’s efforts and vision.

The largest source of uncertainty in dynamic rupture simulations is the selection of initial stresses. Most modelers simply tune the stresses to produce some desired behavior, but Alice’s group integrated multicycle earthquake and geodynamic modeling (spanning thousands to even millions of years) into their workflow. This work informs the long-standing question of the role of splay faults in the subduction fore arc and their role in determining tsunami generation through seafloor uplift.

Through her impressive vision and ambition, Alice-Agnes Gabriel has emerged as perhaps the world’s foremost champion for supercomputing in earthquake science. No less outstanding are her many efforts on behalf of the community. She is an exceptionally worthy recipient of AGU’s Macelwane Medal.

— Eric Dunham
Stanford University
Stanford, California

— Greg Beroza
Stanford University
Stanford, California