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B. J. Andrews

Publications and source records attributed to B. J. Andrews.

2 recordsLinked to original sources

Thermal, deformation, and degassing remote sensing time-series (A.D. 2000-2017) at the 47 most active volcanoes in Latin America: Implications for volcanic systems

Volcanoes are hazardous to local and global populations, but only a fraction are continuously monitored by ground-based sensors. For example, in Latin America, more than 60% of Holocene volcanoes are unmonitored, meaning long-term multi-parameter datasets of volcanic activity are rare and sparse. We use satellite observations of degassing, thermal anomalies, and surface deformation spanning 17 years at 47 of the most active volcanoes in Latin America, and compare these datasets to ground-based observations archived by the Global Volcanism Program (GVP). This first comparison of multi-satellite time-series on a regional scale provides information regarding volcanic behavior during, non-, pre-, syn- and post-eruptive periods. For example, at Copahue volcano, deviations from background activity in all three types of satellite measurements were manifested months to years in advance of renewed eruptive activity in 2012. By quantifying the amount of degassing, thermal output, and deformation measured at each of these volcanoes, we test the classification of these volcanoes as open or closed volcanic systems. We find that ~28% of the volcanoes do not fall into either classification and the rest show elements of both, demonstrating a dynamic range of behavior that can change over time. Finally, we recommend how volcano monitoring could be improved through better coordination of available satellite-based capabilities and new instruments.

Journal of Geophysical Research↗

Explosive dome eruptions modulated by periodic gas-driven inflation

Volcan Santiaguito (Guatemala) “breathes” with extraordinary regularity as the edifice's conduit system accumulates free gas, which periodically vents to the atmosphere. Periodic pressurization controls explosion timing, which nearly always occurs at peak inflation, as detected with tiltmeters. Tilt cycles in January 2012 reveal regular 26 ± 6 min inflation/deflation cycles corresponding to at least ~10 1 kg/s of gas fluxing the system. Very long period (VLP) earthquakes presage explosions and occur during cycles when inflation rates are most rapid. VLPs locate ~300 m below the vent and indicate mobilization of volatiles, which ascend at ~50 m/s. Rapid gas ascent feeds pyroclast-laden eruptions lasting several minutes and rising to ~1 km. VLPs are not observed during less rapid inflation episodes; instead, gas vents passively through the conduit producing no infrasound and no explosion. These observations intimate that steady gas exsolution and accumulation in shallow reservoirs may drive inflation cycles at open-vent silicic volcanoes.

Geophysical Research Letters↗