Inflation‐deflation cycles revealed by tilt and seismic records at Stromboli volcano

Abstract

Strombolian activity is driven by gas dynamic, where large quantities of volatiles are first exsolved and then suddenly released, ejecting fragmented lava at ∼100–300 m height with exit velocities of 20–70 m/s. This conduit process is detected as VLP seismicity only in the final stage (<10 s before the explosion), when the rising gas slug interacts with the shallower part (last 200–300 m) of the feeding conduits. We present new ground deformation recorded with high‐resolution tiltmeters (1 nrad) sampled at 1 Hz and detected by broad‐band seismometers that extends the perception of this explosive process. Tiltmeters and seismometers reveal that the explosive process is accompanied by a persistent deformation of the ground detected as small (<100 nrad) inflation‐deflation cycles ∼250 s long and associated with the constant process of gas recharge and discharge of the magma conduit.