Volcanic eruptions generate sound waves in the atmosphere and seismic waves in the solid Earth. These waves can be recorded at a safe distance from volcanoes and used to constrain eruptive processes that are otherwise obscured from study. This project will develop computer simulations of magma ascent through volcanic conduits in the solid Earth and eruption into the atmosphere that also capture sound and seismic waves. Most current eruption simulations are based on simplifying approximations, like incompressible fluids and rigid solids, that eliminate waves. Simulation results from the project can be used to improve volcano monitoring, data interpretation, and hazard assessment. The project will provide training for a PhD student and postdoctoral scholar, and outreach activities for the general public include volcano-related demos at local elementary school science nights, STEMTaught articles for an elementary-school-level textbook meeting the Next Generation Science Standards, and a Stanford Ask A Scientist webpage.
The eruption simulations will utilize a state-of-the-art aeroacoustics code originally designed to study sound radiation by turbulent jets and shocks created by discharge of high pressure gas from jet engines. The code will be modified to study volcanic eruptions by coupling to an unsteady conduit flow code that models the ascent, depressurization, and fragmentation of magma. Simulations of vulcanian and strombolian eruptions will be used to 1.) assess the validity of commonly used acoustic source models like the point monopole and linear acoustics; 2.) quantify the effects of turbulent entrainment on infrasound generation (facilitating joint interpretation of visual and infrasound data); and 3.) probe subsurface eruptive processes like the rate of depressurization of shallow reservoirs, providing insight into how gas and magma are temporarily stored, pressurized, and released near the vent; also, identify signatures of the descent of the fragmentation surface down the conduit in large vulcanian explosions. Seismic representation theory will be used to convert pressure and momentum changes within the conduit to equivalent seismic moment tensor and force sources in the elastic wave equation. Seismic constraints on eruptive processes like fragmentation will be derived to complement infrasound constraints. This project is supported by the Geophysics and Petrology/Geochemistry programs.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
