Earth's surface is made of soft matter. Sand and mud deform under foot, while even rocks and ice are “squishy” on geologic timescales. This skin of particulate and living material is fragile; excited by a broad spectrum of perturbations, Earth's surface flickers across metastable states. Understanding this soft earth geophysics is existential, to manage the risk of increasingly dangerous natural hazards such as landslides and earthquakes and to learn to build with sustainable geomaterials. This emerging field centers on identifying and advancing common frontiers in geophysics and soft matter physics. Recent studies have revealed how Earth’s surface creates and maintains novel out-of-equilibrium materials and transport phenomena. The memory of earthquakes and floods is encoded in the microstructure of sediments, friction and cohesion conspire to create the wide range of yielding behaviors and feedbacks between organisms and their environment shape flow.

This program seeks to coalesce a community of scientists from soft matter physics and geoscience, to collectively define a set of outstanding questions, and to develop novel approaches to answering them. Scientific themes include metastability and state transitions (e.g., creeping and yielding), localization of strain/failure and the emergence of collective motions, active matter of the living Earth, creation/erasure of material memory, and extracting physics from geophysical observables. This program will also include pedagogical lectures and skills-sharing activities, to foster communication and inclusion among scientists from the diverse backgrounds needed to advance this new field.