Acoustic Noise from Volcanoes: Theory and Experiment

Woulff, Gordon; McGetchin, T. R.

doi:10.1111/j.1365-246x.1976.tb06913.x

Cited by 111 publications

(58 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…No clear blasts are associated with the initiation of these signals. Acoustic records of some eruptions from Stromboli (Woulff and McGetchin 1976) have an appearance similar to the one observed in RO events including (1) emergent onset, (2) coda punctuated by distinct peaks, and, (3) a gradual decay to background. Dominant amplitudes span the 1-4 Hz band with no significant energy above 10 Hz.…”

Section: Jetting Signalsmentioning

confidence: 75%

“…Owing to conservation of material flux, the conduit velocity (U) is assumed to be less than the initial ejection velocity at the vent (v ej ). Therefore, we calculated v ej using the total acoustic power ( ) radiated by these events, based on the assumption that blast-type eruptions can be represented as an ideal monopole acoustic source (Woulff and McGetchin 1976). Total acoustic power, emitted during a time interval (T b ) in a half sphere of radius equal to the distance between the vent and the microphone, is easily calculated by integrating the square of pressure disturbance ( p), using the following expression given by Vergniolle and Caplan-Aubech (2004):…”

Section: Analysis Of Source Locationsmentioning

confidence: 99%

“…Gas exit velocities at volcanic explosions can be obtained using the expression given below (Woulff and McGetchin 1976 ):…”

Section: Analysis Of Source Locationsmentioning

confidence: 99%

See 2 more Smart Citations

Source constraints of Tungurahua volcano explosion events

2005

View full text Add to dashboard Cite

The most recent eruptive cycle of Tungurahua volcano began in May 2004, and reached its highest level of activity in July 2004. This activity cycle is the last one of a series of four cycles that followed the reawakening and major eruption of Tungurahua in 1999. Between June 30 and August 12, 2004, three temporary seismic and infrasonic stations were installed on the flanks of the volcano and recorded over 2,000 degassing events. The events are classified by waveform character and include: explosion events (the vast majority, spanning three orders of pressure amplitudes at 3.5 km from the vent, 0.1-180 Pa), jetting events, and sequences of repetitive infrasonic pulses, called chugging events. Travel-time analysis of seismic first arrivals and infrasonic waves indicates that explosions start with a seismic event at a shallow depth (<200 m), followed ∼1 s later by an out-flux of gas, ash and solid material through the vent. Cluster analysis of infrasonic signals from explosion events was used to isolate four groups of similar waveforms without apparent correlation to event size, location, or time. The clustering is thus associated with source mechanism and probably spatial distribution. Explosion clusters do not exhibit temporal dependence.

show abstract

Section: Jetting Signalsmentioning

confidence: 75%

Section: Analysis Of Source Locationsmentioning

confidence: 99%

See 1 more Smart Citation

Source constraints of Tungurahua volcano explosion events

2005

View full text Add to dashboard Cite

show abstract

“…Because the source of the sound is sometimes difficult to model, Woulff and McGetchin (1976) have suggested use of acoustic power to estimate gas velocity during volcanic eruptions. In this section, we review the different types of sources and apply this method to the 1999 Shishaldin eruption.…”

Section: Gas Velocity From Acoustic Powermentioning

confidence: 99%

“…Explosions, blasts, bubble vibration or balloon bursting are by nature monopole, while a quadrupole source is classically provided by turbulence inside the gas jet. A dipole source is very well adapted to a volcanic gas carrying solid particles (Woulff and McGetchin 1976). In each case, it is possible to calculate acoustic power by assuming that the signal is periodic and monochromatic with a radian frequency ω.…”

Section: Gas Velocity From Acoustic Powermentioning

confidence: 99%

Basaltic thermals and Subplinian plumes: Constraints from acoustic measurements at Shishaldin volcano, Alaska

Vergniolle

Caplan‐Auerbach

2006

Bull Volcanol

View full text Add to dashboard Cite

International audienceAbstract The 1999 basaltic eruption of Shishaldin volcano (Alaska, USA) included both Strombolian and Subplinian activity, as well as a “pre-Subplinian” phase interpreted as the local coalescence within a long foam in the conduit. Although few visual observations were made of the eruption, a great deal of information regarding gas velocity, gas flux at the vent and plume height may be inferred by using acoustic recordings of the eruption. By relating acoustic power to gas velocity, a time series of gas velocity is calculated for the Subplinian and pre-Subplinian phases. These time series show trends in gas velocity that are interpreted as plumes or, for those signals lasting only a short time, thermals. The Subplinian phase is shown to be composed of a thermal followed by five plumes with a total expelled gas volume of $$\approx\!1.5 \times 10^{7}\;{\rm m}^{3}$$. The initiation of the Subplinian activity is probably related to the arrival of a large overpressurised bubble close to the top of the magma column. A gradual increase in low-frequency (0.01–0.5 Hz) signal prior to this “trigger bubble” may be due to the rise of the bubble in the conduit. This delay corresponds to a reservoir located at ≈3.9 km below the surface, in good agreement with studies on other volcanoes. The presence of two thermal phases is also identified in the middle of the pre-Subplinian phase with a total gas release of $$\approx \!4.3 \times 10^{6}\;{\rm m}^{3}$$ and $$\approx \!3.6 \times 10^{6}\;{\rm m}^{3}$$. Gas velocity at the vent is found to be $$\approx \!82\, {\rm m.s}^{-1}$$ and $$\approx \!90\, {\rm m.s}^{-1}$$ for the Subplinian plumes and the pre-Subplinian thermals respectively. The agreement is very good between estimates of the gas flux from modelling the plume height and those obtained from acoustic measurements, leading to a new method by which eruption physical parameters may be quantified. Furthermore, direct measurements of gas velocity can be used for better estimates of the $${\rm SO}_{2}$$ flux released during the eruption

show abstract

Characterization and interpretation of volcanic activity at Karymsky Volcano, Kamchatka, Russia, using observations of infrasound, volcanic emissions, and thermal imagery

Lopez

Fee

Prata

et al. 2013

Geochem Geophys Geosyst

View full text Add to dashboard Cite

[2] A multiparameter data set including measurements of infrasound, volcanic emissions, and thermal imagery is used to characterize and interpret diverse volcanic activity observed during field campaigns in August 2011 and July 2012 at Karymsky Volcano, Kamchatka, Russia. Four activity types are visually identified and characterized according to: SO 2 emission rate, ash mass, event duration, peak temperature, thermal radiation energy, infrasound onset and frequency, reduced infrasonic pressure, and acoustic energy. These activity types include: (1) ash explosions, (2) pulsatory degassing, (3) gas jetting, and (4) explosive eruption. Unique infrasound signals are associated with all four activity types suggesting that infrasound can be used to help remotely and continuously detect and characterize volcanic activity at Karymsky and other similar volcanoes. Our observations suggest that SO 2 is emitted continuously, though in varying abundance, while ash is emitted discontinuously and is only associated with certain types of activity. Our data set supports previous models that attribute variations in surface activity to changes in conduit permeability at Karymsky Volcano. Evidence for a decrease in conduit permeability as a trigger for ash explosions and explosive eruption activity types is supported by weakened but still detectable SO 2 emission rates prior to eruption, along with the highly impulsive infrasonic onset and large reduced infrasound pressure indicating high pressure at the vent. We speculate that changes in conduit permeability at Karymsky Volcano result from changes in magma supply from the shallow-crustal storage region though additional measurements are required to validate this hypothesis.

show abstract

Acoustic Noise from Volcanoes: Theory and Experiment

Cited by 111 publications

References 12 publications

Source constraints of Tungurahua volcano explosion events

Source constraints of Tungurahua volcano explosion events

Basaltic thermals and Subplinian plumes: Constraints from acoustic measurements at Shishaldin volcano, Alaska

Characterization and interpretation of volcanic activity at Karymsky Volcano, Kamchatka, Russia, using observations of infrasound, volcanic emissions, and thermal imagery

Contact Info

Product

Resources

About