Scaling and Transition of the Explosive Activity at Stromboli Volcano

Abstract:

Explosive activity at Stromboli volcano covers a wide energetic and temporal spectrum, spanning from small puffing to violent paroxysms and with the corresponding mass discharge rate ranging 7 orders of magnitude.

At the lowest end, puffing activity is characterized by discrete small pulses of gas and fragments with limited excess pressure, driving gas and ejecta at the rate of 1 kg/s few meters high above the vents and repeating almost persistently at the rate of ~ 1 event every 2 seconds. With increasing mass discharge rate ordinary explosive activity (10³ kg/s) is repeating every ~ few minutes ejecting hot lava fragments at ~200 m height whereas larger (Mayor) explosions are occurring every year with a mass eruptive rate of 10⁵ kg/s driving progressively higher eruptive clouds at ~500 m above the vent.

At the other end of the activity, the paroxysms have a mass discharge rate of 10⁷ kg/s, driving the eruptive column up to few km above the crater and repeating at a rate of one event every ~10 years. Clear limits among these different eruptive styles have not been defined and the dynamics driving this broad explosive spectrum is still debated. We show how seismic, ground tilt and infrasonic data collected at Stromboli since 2008 for a total of ~24000 events provide a geophysical-based classification of explosive activity at Stromboli volcano highlighting changes in eruptive dynamics.