Linking volcanic tremor, degassing, and eruption dynamics via SO₂imaging

Abstract

[1] Recently developed UV cameras offer improvement in remote sensing of volcanic SO 2 , with temporal resolutions of ∼1 Hz and synoptic plume views. Integrated UV camera and seismic measurements recorded in January 2009 at Fuego volcano, Guatemala, provide new insight into the system's shallow conduit processes. High temporal resolution SO 2 data reveal patterns of SO 2 emission rate relative to explosions and seismic tremor that indicate tremor and degassing share a common source process. Progressive decreases in emission rate appear to represent inhibition of gas loss from magma as a result of rheological stiffening in the upper conduit. Measurements of emission rate from two closely-spaced vents, made possible by the high spatial resolution of the camera (1024 × 1024 pixels), help constrain this model. This inter-disciplinary approach illuminates eruptive processes at Fuego and holds promise for gaining similar understanding at other volcanic systems.

Ultraviolet Imaging of Volcanic Plumes: A New Paradigm in Volcanology

“…These experimental outcomes are as would be expected, given that tremor is anticipated to increase with elevated bubble concentrations in magmas, or the more rapid flow of bubbles in the conduit, scenarios which would both correspond to periods of elevated gas release. In two of the studies, intriguing lag relationships were identified [20,44]. In particular, in Nadeau et al [20], a trend of increasing temporal lags between the seismic and gas flux time series was observed in the period following explosions, implying perhaps that the source of seismic energy was becoming progressively deeper within the conduit due to the rheological stiffening of the magma downwards from the top of the column.…”

“…In two of the studies, intriguing lag relationships were identified [20,44]. In particular, in Nadeau et al [20], a trend of increasing temporal lags between the seismic and gas flux time series was observed in the period following explosions, implying perhaps that the source of seismic energy was becoming progressively deeper within the conduit due to the rheological stiffening of the magma downwards from the top of the column. In Pering et al [44], bursts in CO 2 outgassing were reported (derived from the UV cameras in tandem with Multi-GAS [3] units) which preceded spikes in seismicity, raising intriguing questions regarding the causal processes that might link these phenomena in this case.…”

“…By gathering spatial information, the cameras implicitly provide scope for the resolution of gas fluxes from heterogenous sources, as exploited on Vulcano island (Italy), to measure gas fluxes from individual fumaroles [39]. This capability has also been exploited in respect of multiple vent scenarios, e.g., Fuego (Guatemala) [20] and Mt. Etna, where a shifting of degassing from one vent to another was observed in tandem with a transference of eruptive activity between craters [34].…”

“…Here, a number of studies have noted a relationship between these time series for the Etna, Fuego, and Kīlauea volcanoes, including conduit and lava lake degassing scenarios [20,40,44,46]. In one case, this has involved novel signal processing techniques based on wavelet analysis to isolate commonality in periodicity in pairs of geophysical datastreams [57].…”

“…These series are then cross-correlated to determine the temporal lag between them, from which the transit speed can be found [17,18]. Alternately, more sophisticated motion-tracking algorithms have also been applied [19], as has the correlation of temporally successive spatial series/longitudinal profiles of the plume to better exploit the available two-dimensional (2D) information in determining plume velocities [20]. Multiplication of the transport speed by one of the integrated column amount time series then leads to the generation of the flux time series.…”