Source mechanisms of explosions at Stromboli Volcano, Italy, determined from moment‐tensor inversions of very‐long‐period data

Chouet, Bernard; Dawson, Phillip B.; Ohminato, Takao; Martini, M.; Saccorotti, Gilberto; Giudicepietro, Flora; Luca, Gaetano De; Milana, Giuliano; Scarpa, Roberto

doi:10.1029/2002jb001919

Cited by 353 publications

(460 citation statements)

References 48 publications

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“…The selection of the most likely mechanism is based on the squared error, the relevance of the free parameters used in the model, and the physical significance of the resulting source mechanism. We use two measures of squared error to evaluate the waveform fits in the time domain [Ohminato et al, 1998;Chouet et al, 2003] …”

Section: Evaluation Of the Resultsmentioning

confidence: 99%

“…of such a pipe is described by the same q and f used to orient the normal to the tension crack. For n = 1/3, the ratios of the principal axes of a pipe are [1.5:1.5:1.0] where the smaller value is parallel to the axis [Chouet, 1996b]. We can construct the following combined source: [1:1:2] À 0.2 Â [1.5:1.5:1.0], which yields [0.78:0.78:2.00] after normalizing.…”

Section: Vlp Bandmentioning

confidence: 99%

“…The crack moment tensors are calculated using equation (15) of Chouet [1996b] and assuming l = m. Using a grid search, we obtain a source time function for each crack and set of forces for cracks with the following orientations: we use 5°increments for q over the interval 0° q 45°and we use 10°increments for f over the intervals 180° f 360°plus 0° f 30°. The source time functions for each mechanism are multiplied by the theoretical moment tensor to obtain the source time functions for the tensor components.…”

Section: Lp Bandmentioning

confidence: 99%

“…[49] The three components of a diagonalized moment tensor representing a tensile crack have amplitudes lDV, lDV, and (l + 2m) DV, where l and m are the Lamé constants of the host rock and DV represents the volume change associated with the crack opening or closing [Aki and Richards, 1980;Chouet, 1996b]. If we assume the crack wall rock behaves as a Poisson solid (l = m), the ratios of the principal axes are [1:1:3], very close to those of our diagonalized moment tensor.…”

Section: Lp Bandmentioning

confidence: 99%

“…[9] Where VLP earthquakes have been observed [Kawakatsu et al, 1992;Kawakatsu et al, 1994;Neuberg et al, 1994;Kaneshima et al, 1996;Ohminato et al, 1998;Arciniega-Ceballos et al, 1999;Legrand et al, 2000;Nishimura et al, 2000;Rowe et al, 2000;Kumagai et al, 2001;Almendros et al, 2002;Hidayat et al, 2002;Hill et al, 2002;Aster et al, 2003;Chouet et al, 2003Chouet et al, , 2005 they are typically attributed to fluid-rock interactions, as with LP events. However, instead of resonance in a fluid-filled crack, VLP events may result from longer-term inertial volume changes in fluid conduits.…”

Section: Introductionmentioning

confidence: 99%

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

2008

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[1] The current eruption at Mount St. Helens is characterized by dome building and shallow, repetitive, long-period (LP) earthquakes. Waveform cross-correlation reveals remarkable similarity for a majority of the earthquakes over periods of several weeks. Stacked spectra of these events display multiple peaks between 0.5 and 2 Hz that are common to most stations. Lower-amplitude very-long-period (VLP) events commonly accompany the LP events. We model the source mechanisms of LP and VLP events in the 0.5-4 s and 8-40 s bands, respectively, using data recorded in July 2005 with a 19-station temporary broadband network. The source mechanism of the LP events includes: 1) a volumetric component modeled as resonance of a gently NNW-dipping, steam-filled crack located directly beneath the actively extruding part of the new dome and within 100 m of the crater floor and 2) a vertical single force attributed to movement of the overlying dome. The VLP source, which also includes volumetric and single-force components, is 250 m deeper and NNW of the LP source, at the SW edge of the 1980s lava dome. The volumetric component points to the compression and expansion of a shallow, magmafilled sill, which is subparallel to the hydrothermal crack imaged at the LP source, coupled with a smaller component of expansion and compression of a dike. The single-force components are due to mass advection in the magma conduit. The location, geometry and timing of the sources suggest the VLP and LP events are caused by perturbations of a common crack system.

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Section: Evaluation Of the Resultsmentioning

confidence: 99%

Section: Vlp Bandmentioning

confidence: 99%

Section: Lp Bandmentioning

confidence: 99%

Section: Lp Bandmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2008

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Dynamics of Strombolian explosions: Inferences from field and laboratory studies of erupted bombs from Stromboli volcano

et al. 2014

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Strombolian activity is characterized by repeated, low energy, explosions and is named after the volcano where such activity has persisted for around 2000 years, i.e., Stromboli (Aeolian Islands, Italy). Stromboli represents an excellent laboratory where measurements of such explosions can be made from safe, but close, distances. During a field campaign in 2008, two 15 cm diameter bombs were quenched and collected shortly after a normal explosion. The bombs were characterized in terms of their textural, chemical, rheological, and geophysical signatures. The vesicle and crystal size distribution of the samples, coupled with the glass chemistry, enabled us to quantify variations in the degassing history and rheology of the magma resident in the shallow (i.e., in last 250 m of conduit length). The different textural facies observed in these bombs showed that fresh magma was mingled with batches of partially to completely degassed, oxidized, high-crystallinity, high-viscosity, evolved magma. This magma sat at the top of the conduit and played only a passive role in the explosive process. The fresh, microlite-poor, vesiculated batch, however, experienced a response to the explosive event, by undergoing rapid decompression. Integration of geophysical measurements with sample analyses indicates that popular bubble-bursting models may not fit this case. We suggest that the degassed, magma forms a plug, or rheological layer, at the top of the conduit, through which the fresh magma bursts. In this model we need to consider the paradox of a slug ascending too fast through a magma of varying viscosity and yield strength.

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Source mechanism of Vulcanian eruption at Tungurahua Volcano, Ecuador, derived from seismic moment tensor inversions

Kim

Lees

Ruiz

2014

J. Geophys. Res. Solid Earth

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Source mechanisms of explosive volcanic eruptions are critical for understanding magmatic plumbing systems and magma transport. Tungurahua is a large andesitic stratovolcano where seismoacoustic data has been recorded over several years. In May 2010, an energetic eruption cycle began with a midsize Vulcanian explosion followed by swarms of explosive eruptions. The five-station seismoacoustic network recorded significant seismic and infrasonic signals from the explosions. Source mechanisms of 50 explosion earthquakes associated with Vulcanian explosions during this eruptive period are investigated here. The source centroid locations and geometries of explosive signals in the 10-2 s band were determined by full-waveform moment tensor inversion. The observed waveforms are well explained by a combination of volumetric moment tensor components and a single, vertical, downward force component. The source centroids are positioned about 1.5 km below and about 320 m north of the active crater. Eigenvalue and eigenvector analysis indicates that the source geometries can be described by a subhorizontal, thin ellipsoid representing a sill-like magma accumulation. Resultant source time histories show a repetitive sequence of inflation and deflation from event to event, indicating identical source processes frequently occurred over the period. The inflation/deflation in the deep source region may be the result of crack opening. Volatile bubble growth at depth opens a pathway for gases to escape and triggers shallow explosions at the summit crater. The associated downward single force is interpreted as an exchange of linear momentum between the source and the surrounding region during the escaping gas flow.

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Source mechanisms of explosions at Stromboli Volcano, Italy, determined from moment‐tensor inversions of very‐long‐period data

Cited by 353 publications

References 48 publications

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

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

Dynamics of Strombolian explosions: Inferences from field and laboratory studies of erupted bombs from Stromboli volcano

Source mechanism of Vulcanian eruption at Tungurahua Volcano, Ecuador, derived from seismic moment tensor inversions

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