Silent Very Long Period Seismic Events (VLPs) at Stromboli Volcano, Italy

At Stromboli Volcano, Italy, very long period (VLP) seismic signals and Strombolian eruptions have been attributed to the unsteady flow of gas slugs through shallow plumbing system followed by explosive slug bursting at a free surface. In data from 2018 seismo-acoustic deployment, ∼92% events in two main VLP multiplets do not coincide time with impulsive infrasonic (the expected signal bursting); we term these “silent VLPs.” The lack infrasonically detected explosions relative repeating VLPs does support commonly invoked “gas slug” model. We propose that may be generated when bubbles move into weak semi-solid plug uppermost portion conduit. then acts as mechanical filter which pathways vary guide or trap ascending slugs, allowing for passive (silent) release escape mechanisms decoupled VLPs.