Trends in activity at Pu’u ’O’o during 2001–2003: Insights from the continuous thermal record
Published:January 01, 2008
Emanuele Marchetti, Andrew J. L. Harris, 2008. "Trends in activity at Pu’u ’O’o during 2001–2003: Insights from the continuous thermal record", Fluid Motions in Volcanic Conduits: A Source of Seismic and Acoustic Signals, S. J. Lane, J. S. Gilbert
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A permanent thermal monitoring system deployed on the north rim of Pu'u 'O'o crater (Kilauea, Hawaii) provided an 811-day-long data-set spanning March 2001–December 2003. These data allowed us to characterize three emission styles from vents on the crater floor: lava flows, sustained degassing and gas-piston events. Lava flows were recorded as sudden increases in temperature followed by smooth and relatively long-lasting decreases as the lava cooled. Sustained degassing was associated with persistently high levels of thermal signal and was the most common signal type. Finally, gas-piston events were all preceded by marked reductions in temperature (due to diminished degassing) and were marked by abrupt increases (due to the arrival of a gas jet) followed by 50–300 second waning phases. Lava flow occurrence, maximum temperature recorded during degassing, gas-piston thermal amplitude, occurrence and waveform all showed coupled, systematic changes through time. This implies modification of a common source process, and may be a result of a slight change in the magma level beneath the crater so as to modify the conduit geometry/primary degassing pathways, and hence gas collection and release processes, as well as slug ascent dynamics.
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Fluid Motions in Volcanic Conduits: A Source of Seismic and Acoustic Signals
Volcanoes become active when fluids are in motion, and erupt when these fluids escape into the atmosphere. Volcanic fluids are a mixture of solid, liquid and gas. These mixtures result in a complex range of flow behaviour, especially during interaction with conduit geometry. These processes are not directly observable and must be inferred from interpretations of field observation and measurement. One of the outcomes of this complexity is the generation of pressure and force transients as high-density phases accelerate and decelerate during unsteady flow. These transients are one means of flexing the conduit wall, a process that manifests itself as ground motion and is detectable as volcano seismic signals. On eruption, volcanic fluids interact with the atmosphere and generate acoustic and thermal signals. In this Special Publication we present a series of papers based on field, numerical and experimental approaches that seek to establish links between geophysical signals and fluid motion in volcanic conduits.