Citation by Simon L Klemperer
It is my honor to introduce Larry Brown as our George P. Woollard award winner for 2024. Like Woollard, Larry took his first degree at Georgia Tech, before varied paths led each of them to national and international leadership in geophysical studies of the continental crust.
Larry Brown’s career has been driven by continual experimentation with different seismic technologies, from seismic vibrators to microearthquake sources to scattered-wave interferometry, as applied to different problems from the deep lithosphere to shallow archeological and geothermal targets.
Larry is associated with at least three discoveries that transformed our understanding of mountain building: the anatomy of the Appalachian orogen; the deep structure of the Urals; and the evolution of the Tibetan Plateau. Larry Brown energized the leadership team of the Consortium for Continental Reflection Profiling (COCORP) and was part of the early transformational discovery that the Appalachians are a thin-skinned orogen, and the Blue Ridge thrust not a high-angle fault cutting the whole crust but rather part of a low-angle detachment traceable for over 250 km. This remarkable image of orogen-scale horizontal transport settled a century-long controversy, demonstrated to the world that seismic reflections could map the large-scale structures that elude the outcrop-scale focus of some structural geologists, and launched the international proliferation of national programs in Canada, Europe and beyond.
Larry became the biggest international cheer-leader for seismic reflection profiling, and drove international co-operative field experiments in Russia and in Tibet. The URSEIS program discovered reflections cutting through the whole lithosphere to ~200-km depth and the preservation of a Paleozoic deep continental root to the Urals. In contrast to this post-orogenic stability, the INDEPTH program across Tibet discovered that orogenic plateaux are not supported by strong crust but underlain by weak and deformable crust. In his most highly cited paper, Larry recognized that ‘bright-spots’—high-amplitude seismic reflections—are the signature of active magmatism in the middle crust of Tibet, inspiring the modern paradigm of channel-flow as the controlling mechanism for large, hot orogens, as important in the lower crust as brittle faulting in the upper crust.
Larry’s enthusiastic persistence has led to revelatory imaging of compressional orogeny and continental collision, and his signature reflection profiles have an important place in today’s textbooks of Geophysics and Geodynamics.