Valère Lambert is the rare breed of theorist with a deep understanding of the important questions who can craft both analytical and numerical approaches. Valère has already produced several fundamental theoretical papers in his short career thus far. His 2021 Nature paper revisits one of the oldest, and most fundamental, problems of earthquake physics with fresh eyes. The problem of the absolute stress on faults is central to earthquake physics. Are earthquakes operating at near-lithostatic stresses, as one might expect from the overburden, or are they operating at low stresses, as one might infer from the lack of conspicuous thermal anomalies? Many have speculated based on cartoons that the radiated energy should be diagnostic of the difference; however, no one had shown it. Valère showed it and pointed out fairly clearly that large, subduction zone earthquakes are likely operating at low stresses. To make the argument, he also pulled in an important thread of rupture behavior and showed that the subduction earthquakes are likely crack-like, that is, slip over the whole fault at once, rather than pulse-like. It is a good paper in part because of virtuosic mastery of the multiple threads of thinking on the problem. This is one of Valère’s trademarks. He has an overview of the field seldom seen at any career stage, let alone as early he is now. His other forays into earthquake physics include poroelasticity, and viscous flow modeling in addition to fracture mechanics. These are all technically challenging subjects that he has both mastered and made real contributions to at a surprisingly early career stage. His accomplishments are already impressive, and he richly deserves this honor. —Emily Brodsky, University of California, Santa Cruz

I am very honored to receive the Keiiti Aki Early Career Award. I thank the AGU Seismology section for this recognition, which truly reflects the insights and support from many mentors, collaborators, and friends. I particularly want to acknowledge Nadia Lapusta, Emily Brodsky, Jean-Philippe Avouac, Mark Simons, Zhongwen Zhan, Victor Tsai, Hiroo Kanamori, Tom Heaton, Dan Faulkner, Zach Ross, Nick Beeler, and Jeff McGuire for their tremendous support and inspiration. I want to express my gratitude to the seismology and broader geology, geophysics, and mechanics communities, and the numerous members with whom I have had the privilege to interact and learn from. Earthquake science, as with many areas of geoscience, is full of fascinating and challenging interdisciplinary problems, and it has been an enriching experience to gain perspectives from an array of vantage points. As a theorist, it is inspiring to see the work and creativity involved in procuring the observations that illuminate different aspects of these puzzles. I look forward to the new insights to come from the increasing volume and richness of field and laboratory observations and new tools for analyzing such high-dimensional data. —Valère Lambert, University of California, Santa Cruz