Eruption dynamics at Mount St. Helens imaged from broadband seismic waveforms: Interaction of the shallow magmatic and hydrothermal systems

Waite, G. P.; Chouet, Bernard; Dawson, Phillip B.

doi:10.1029/2007jb005259

Cited by 120 publications

(243 citation statements)

References 65 publications

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“…[71] We next investigate the possibility that the tilt was generated by a VLP source modeled by Waite et al [2008]. As noted earlier, VLP events during the summer of 2005 were found to be consistent with the opening and closing of a sill-dike combination located below the SW edge of the 1980s lava dome.…”

Section: Opening/closing Crack and Vlp Sourcementioning

confidence: 98%

“…Iverson et al [2006] modeled the drumbeat events as caused by repeating slip on the margin of the ascending magma plug. Waite et al [2008] however, analyzed long-period seismic events recorded during the summer of 2005, and concluded that these events were inconsistent with a shear-faulting source and suggested instead the repetitive opening and closing of a steam-or fluid-filled crack or cracks located beneath the growing lava dome. Waite et al [2008] also analyzed very long period (VLP) events (periods of 15-25 s) during the same time and suggested that the source mechanism for these events involved the contraction and expansion of a sill and dike system located beneath the SW edge of the 1980s lava dome.…”

Section: The 2004-2008 Eruption Of Mount St Helensmentioning

confidence: 99%

“…It also seems possible that frictional slip occurred at the margins of the plug at different times, such that slip on one part of the plug then would have led to outward tilt, while slip elsewhere would have led to inward Figure 19. Monte Carlo inversions for an opening crack constrained to lie near the location of the best fitting VLP source of Waite et al [2008]. See Figure 16 caption for more information.…”

Section: Other Modelsmentioning

confidence: 99%

“…The reduced chi-square metric is defined by c red 2 = c 2 /(n − p) where c 2 = r T S −1 r and n is the number of observations (here, 10). The opening sill is fixed to the location of the VLP source modeled by Waite et al [2008], so has few free parameters. Depths for dislocation sources specify the bottom edge of the fault, and for the depressurizing conduit the depth is to the top of the source.…”

Section: Rapid Depressurization Associated With Extrusion or Gas Lossmentioning

confidence: 99%

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Cyclic ground tilt associated with the 2004–2008 eruption of Mount St. Helens

2010

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[1] The long-term behavior of the 2004-2008 effusive eruption of Mount St. Helens was characterized by a gradual decline in the rates of seismicity, dome growth, and broad-scale ground deformation, but shallow near-periodic "drumbeat" earthquakes over timescales of minutes indicated episodic short-term behavior. In part to better characterize this behavior and any associated ground deformation, a network of tiltmeters was installed and recorded thousands of cyclic tilt events within the crater. The duration of these events, from minutes to hours, was too long for them to be directly caused by the drumbeat seismicity. Tilt events were characterized by a recoverable, asymmetric pattern of rapid tilt away from the vent followed by a more gradual reversal, were highly correlated between different tiltmeters in the crater, sometimes occurred in association with volcanic seismicity, and ceased at the end of the eruption. Tilt vectors converged on a point just south of the center of the preexisting 1980s lava dome, and the absence of detectable tilt outside the crater suggests a shallow source (<1 km). We examine several models, including cycles of conduit pressurization and plug slip or gas loss and stick-slip behavior on the interface between the ascending plug and the 1980s lava dome. The small number of stations within the crater prevents a unique determination of source type or geometry, but results are consistent with a mechanism involving extrusion of the semisolid dacite plug and/or cycles of conduit pressurization.

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Section: Opening/closing Crack and Vlp Sourcementioning

confidence: 98%

Section: The 2004-2008 Eruption Of Mount St Helensmentioning

confidence: 99%

Section: Other Modelsmentioning

confidence: 99%

Section: Rapid Depressurization Associated With Extrusion or Gas Lossmentioning

confidence: 99%

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Cyclic ground tilt associated with the 2004–2008 eruption of Mount St. Helens

2010

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“…Numerous source models exist to explain LP signals at volcanoes. These often invoke pressure fluctuations that result from the unsteady movement of bubbly magma [e.g., Chouet, 1996;Kumagai et al, 2002] or steam [Waite et al, 2008] through volcanic conduits and sometimes extend to include the venting of pressurized fluids into the atmosphere and generation of infrasound [Matoza et al, 2009]. Periodic strain changes induced by the oceanic microseism have also been cited as a trigger for hydrothermal LP events [Stich et al, 2011].…”

Section: Introductionmentioning

confidence: 99%

Distinguishing high surf from volcanic long‐period earthquakes

Lyons

Haney

Fee

et al. 2014

Geophysical Research Letters

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Repeating long-period (LP) earthquakes are observed at active volcanoes worldwide and are typically attributed to unsteady pressure fluctuations associated with fluid migration through the volcanic plumbing system. Nonvolcanic sources of LP signals include ice movement and glacial outburst floods, and the waveform characteristics and frequency content of these events often make them difficult to distinguish from volcanic LP events. We analyze seismic and infrasound data from an LP swarm recorded at Pagan volcano on 12-14 October 2013 and compare the results to ocean wave data from a nearby buoy. We demonstrate that although the events show strong similarity to volcanic LP signals, the events are not volcanic but due to intense surf generated by a passing typhoon. Seismo-acoustic methods allow for rapid distinction of volcanic LP signals from those generated by large surf and other sources, a critical task for volcano monitoring.

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Seismological analysis of conduit dynamics in fragmentation experiments

Arciniega-Ceballos¹,

Alatorre‐Ibargüengoitia

Scheu

et al. 2014

JGR Solid Earth

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We simulate gas-burst and volcanic explosions under controlled laboratory conditions inducing fragmentation of volcanic rocks by rapid depressurization. A series of experiments were performed in a shocktube apparatus at room temperature and a pressure range of 4 to 20 MPa using Argon (Ar) gas and, particles or pumice samples of different porosities. The instrumentation of this system with high-precision piezoelectric sensors enabled us to capture elastic waves and to recognize their characteristic signatures. By relating these signals to physical processes in the wave field, we have been able to characterize the conduit mechanism and the source dynamics. We compare and discuss conspicuous features of the waveforms and frequency spectra of these experimental signals with those of volcanic origin. Despite the fact that these signals are different in amplitude (resulting from different scale conditions); our observations indicate that the physical processes that occur during simulated explosions and those that occur during volcanic eruptions yield comparable signatures in their respective records. The effects of the source-receiver configuration and resonance also have significant implications. All this suggests that the physical processes (e.g. pressurization and depressurization of a system) involve a system response that causes similar distinctive effects independent of the system size, reflecting its intrinsic dynamics. These similarities imply that powerful constraints on the source mechanisms of volcanic seismicity can emerge from seismic investigations of experimental simulations of volumetric sources. Such constraints may yield significant advances in the understanding of volcanic conduit dynamics and in the interpretation of seismic unrest at volcanic centers.

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Eruption dynamics at Mount St. Helens imaged from broadband seismic waveforms: Interaction of the shallow magmatic and hydrothermal systems

Cited by 120 publications

References 65 publications

Cyclic ground tilt associated with the 2004–2008 eruption of Mount St. Helens

Cyclic ground tilt associated with the 2004–2008 eruption of Mount St. Helens

Distinguishing high surf from volcanic long‐period earthquakes

Seismological analysis of conduit dynamics in fragmentation experiments

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