Our group uses seismic and infrasonic waves to investigate how volcanoes work. Infrasound is atmospheric sound with frequencies below 20 Hz, the lower frequency limit of human hearing. With seismology, we study magmatic, hydrothermal, and faulting processes occurring within and around volcanoes. With infrasound, we study the mechanisms and dynamics of explosive eruptions and shallow volcanic degassing. This work is focused on understanding the geophysical signatures of volcanic unrest and eruption, with application in monitoring and mitigating volcanic hazards.