Determining the ascent rate of magma during its rise to the surface is challenging yet crucial as it may relate to the style of volcanic eruptions, and modelling dissolved volatiles in crystal-hosted melt embayments is one effective method to estimate these rates. Previous studies suggest that magma ascent rates in basaltic volcanoes may positively correlate with eruption magnitude. Stromboli volcano (Italy) is an ideal case study because its unique plumbing system produces eruptions with variable eruption styles and magnitudes. Magma ascent rates of eight historical eruptions were calculated using (1) diffusion of H2O in embayments, and (2) vesicle population and textural analysis. Embayments record rapid ascent initiation from 1.6 to 7.2 km deep. We obtained average decompression rates of 0.32–6.2 MPa·s−1 (ascent rate of 11–226 m·s−1) for the last step of magma ascent within the conduit system, which agrees with Li diffusion in plagioclase and the timescales of ground deformation at Stromboli recorded immediately before explosive events. Vesicle number density of tephra clasts provides decompression rates within the same order of magnitude (0.55–6.09 MPa·s−1), confirming shallow very fast ascent within the conduit. We identify a strong positive correlation between decompression rates with (1) eruption magnitude, (2) mass eruption rate and (3) embayment H2O-CO2 solubility pressure for eruptions spanning several orders of magnitude in intensity, with faster decompression rates from greater pressures producing the highest intensity eruptions. We suggest such behaviour should be expected at other basaltic volcanoes as well.
Deeper, faster, stronger? Extreme magma ascent rates and explosive eruption metrics at Stromboli volcano (Italy)
Pistolesi M.Ultimo
2026-01-01
Abstract
Determining the ascent rate of magma during its rise to the surface is challenging yet crucial as it may relate to the style of volcanic eruptions, and modelling dissolved volatiles in crystal-hosted melt embayments is one effective method to estimate these rates. Previous studies suggest that magma ascent rates in basaltic volcanoes may positively correlate with eruption magnitude. Stromboli volcano (Italy) is an ideal case study because its unique plumbing system produces eruptions with variable eruption styles and magnitudes. Magma ascent rates of eight historical eruptions were calculated using (1) diffusion of H2O in embayments, and (2) vesicle population and textural analysis. Embayments record rapid ascent initiation from 1.6 to 7.2 km deep. We obtained average decompression rates of 0.32–6.2 MPa·s−1 (ascent rate of 11–226 m·s−1) for the last step of magma ascent within the conduit system, which agrees with Li diffusion in plagioclase and the timescales of ground deformation at Stromboli recorded immediately before explosive events. Vesicle number density of tephra clasts provides decompression rates within the same order of magnitude (0.55–6.09 MPa·s−1), confirming shallow very fast ascent within the conduit. We identify a strong positive correlation between decompression rates with (1) eruption magnitude, (2) mass eruption rate and (3) embayment H2O-CO2 solubility pressure for eruptions spanning several orders of magnitude in intensity, with faster decompression rates from greater pressures producing the highest intensity eruptions. We suggest such behaviour should be expected at other basaltic volcanoes as well.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
