Hazardous phenomena at volcanoes includes ash plumes, gas emissions, explosions, pyroclastic density currents, lava flows, lahars, and mass wasting. All of these processes produce seismic and infrasound signals that can provide key real-time information for assessing hazardous surface activity. We can also gain insights into the activity state of volcanoes by identifying and tracking the movement of subsurface magma and hydrothermal fluids using seismicity and seismic imaging techniques. Recent advances in hardware technology and data analysis have promoted more precise characterization and quantification of the physical mechanisms leading to and producing hazardous volcanic phenomena. Nevertheless, volcano seismology and acoustics remains a rapidly developing area of research. We welcome submissions that present new seismic and acoustic observations, interpretations, models, instrumentation, or techniques that improve our understanding of volcanic processes and assist future monitoring efforts.