Abstract
Identifying and monitoring the presence of pressurized magma beneath volcanoes allows for improved understanding of internal dynamics and prediction of eruptions. Here we show with time-repeated tomography clear evidence that fresh melts accumulate since 2019 in three reservoirs located at different depths in the central feeding system. In these three volumes, we observe a significant reduction of seismic wave velocity, an anomaly that has endured for almost two years. Reservoir re-pressurization induced seismicity clusters around the pressurized volumes within high fluid pressure compartments. This indicated a sharp change in volcano behavior, with re-pressurization of the central system replacing two-decade-long, flank collapse-dominated dynamics. The volume where the velocities are altered is remarkable in size, suggesting the injection of new melt, and that erupted lava represents only a small percentage. Our findings suggest that ongoing volcanic recrudescence can persist.
Highlights
Identifying and monitoring the presence of pressurized magma beneath volcanoes allows for improved understanding of internal dynamics and prediction of eruptions
Its hybrid origin emphasizes a variety of processes and complex dynamics raised by the contamination of a pristine low viscosity magma sourced by the asthenosphere above a vertical slab window[3,4,5]
In time-lapse tomography, 4D velocity changes are computed by differences between 3D images obtained by data that span different time intervals[14,15,16,17]
Summary
Identifying and monitoring the presence of pressurized magma beneath volcanoes allows for improved understanding of internal dynamics and prediction of eruptions. We show with time-repeated tomography clear evidence that fresh melts accumulate since 2019 in three reservoirs located at different depths in the central feeding system In these three volumes, we observe a significant reduction of seismic wave velocity, an anomaly that has endured for almost two years. The present violent eruptive episode with spectacular lava fountains started in mid-February 2021 This sharp reactivation, still ongoing at the time we are writing, follows an overall inflation trend observed by GNSS data and a general increase in seismicity since summer 2020, suggesting a resumption of pressurization in the magmatic system[8]. Since mid-February 2021 to April 2021, the number of strong lava fountain episodes constantly increased, accompanied by a sharp increment in volcanic tremor amplitude and infrasonic activity, but with scarce earthquakes and moderate tiltmetric variations[9]. The observed transient anomalies help in understanding the ongoing dynamics and quantifying the percentage of melt recently added to the system, useful to forecast the evolution of the unrest
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