Seismic evolution of the 1989–1990 eruption sequence of Redoubt Volcano, Alaska

Power, John A.; Lahr, John C.; Page, Robert A.; Chouet, Bernard; Stephens, C. D.; Harlow, David H.; Murray, Thomas L.; Davies, John N.

doi:10.1016/0377-0273(94)90029-9

Cited by 125 publications

(67 citation statements)

References 13 publications

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“…Others correspond to tectonic activity, especially the earthquakes of the Pisayambo seismogenic zone, and the main shock and aftershock sequence of a local 4.2 tectonic earthquake (July 30, 2004). (Power et al 1994). Figure 3 shows the distribution of these categories.…”

Section: Experiments Descriptionmentioning

confidence: 97%

Source constraints of Tungurahua volcano explosion events

2005

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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.

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Section: Experiments Descriptionmentioning

confidence: 97%

Source constraints of Tungurahua volcano explosion events

2005

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“…The detailed seismological studies conducted at Redoubt Stephens et al 1994;Chouet et al 1994;Power et al 1994;Benz et al 1996) provided new insights into source processes during a preeruptive phase of a volcano. The results of quantitative analyses of the precursory LP swarm based on the fluid-driven crack model suggested a mechanism of excitation similar to that observed in choked flow experiments conducted in the laboratory (Meier et al 1978(Meier et al , 1990 and provided the impetus for more detailed studies of volcanic fluid dynamics at transonic conditions in a conduit.…”

Section: Dynamics Of Crack Excitationmentioning

confidence: 99%

New Methods and Future Trends in Seismological Volcano Monitoring

Chouet

1996

Monitoring and Mitigation of Volcano Hazards

186

168

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Volcanic processes operate over a wide range of time scales that require a variety of instruments and techniques for their study. Short-period seismology typically covers the band 0.1-1 s, while broadband seismology can extend that band to 0.1-100 s. Borehole strainmeters may be used to cover the very wide band from 0.1 s to 100 days and Global Positioning System (GPS) surveys are useful to track deformation over time scales ranging from days to decades. Arrays of threecomponent broadband seismographs coupled with arrays of borehole strainmeters are required to monitor the dynamics of magmatic and hydrothermal fluids prior to and during eruptions. Inversions of broadband data may be performed to image the forces operating at a source and infer the fluid pathway geometry and mass transport balance in a volcano. The accuracy of such inversions depends on the degree of resolution achieved for the volcanic structure. High-resolution tomography based on iterative inversions of seismic travel-time data can image three-dimensional structures at a scale of a few hundred meters provided adequate local short-period earthquake data are available. Hence, forces in a volcano are potentially resolvable for periods longer than a few seconds. Studies of long-period events and tremor at periods ~ I s offer constraints on pressure fluctuations resulting from unsteady mass transport, and observations of volcano-tectonic activity tell us about hydraulic fracturing processes, as well as brittle response of the rock matrix to stress changes induced by rapid injection and/or withdrawal of fluids. Short-period networks are routinely used to monitor, locate, and assess the source properties of volcano-tectonic earthquakes and long-period events, while small-aperture seismic antennas are required to track tremor and separate source, path, and site effects in tremor wavefields. This chapter reviews quantitative methods used in the interpretation of source processes and structures in volcanoes and discusses some of the major challenges faced by volcano seismologists in their quest to understand eruptive behavior.

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“…In most classi¢cation schemes (Minakami, 1960;Latter, 1979;Power et al, 1994) the term 'volcanic tremor' is being used in order to describe tremor signals of varying amplitude and duration. Other terms and modi¢ers have also been used, that characterise the appearance of the signal in the time or frequency domain (Table 1).…”

Section: The Nature Of Volcanic Tremormentioning

confidence: 99%

Nature, wavefield properties and source mechanism of volcanic tremor: a review

Konstantinou

Schlindwein

2003

Journal of Volcanology and Geothermal Research

184

129

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Volcanic tremor has attracted considerable attention by seismologists because of its potential value as a tool for forecasting eruptions and better understanding the physical processes that occur inside active volcanoes. However, unlike tectonic earthquakes where the dominant source process is brittle failure of rock, the driving mechanism of tremor seems to involve complex interactions of magmatic fluids with the surrounding bedrock. These interactions are responsible for the following distinct characteristics found in volcanic tremor recorded at many volcanoes worldwide: (a) the onset of tremor may be emergent or impulsive, with its amplitude showing in many cases a direct relationship to the volcanic activity; (b) in the frequency domain the spectra consist of a series of sharp peaks in the band 0.1^7 Hz, representing either a fundamental frequency and its harmonics, or a random distribution, while quite often they exhibit temporal variations in their content; (c) the depth of the source can vary considerably from one volcano to another in the range of a few hundred metres to 40 km; (d) tremor may occur prior to and/or after eruptions with a duration that ranges from several minutes to several days or months. The methods used to study tremor include spectral analysis using both the Fast Fourier Transform and the Maximum Entropy Method, polarisation analysis of the wavefield and methods that make use of array data to deduce the backazimuth and type of the seismic waves as well as the location of the source. Visual and/or recorded acoustic observations of the ongoing volcanic activity have assisted in many cases to further constrain proposed physical mechanisms for the generation of tremor. The models suggested as possible sources of tremor can be grouped as follows: (a) fluid-flow-induced oscillations of conduits transporting magmatic fluids; (b) excitation and resonance of fluid-filled cracks; (c) bubble growth or collapse due to hydrothermal boiling of groundwater; (d) a variety of models involving the oscillations of magma bodies with different geometries. It has been proposed by many authors that the source of tremor is not unique and may differ from one volcano to another, a fact that adds more difficulty in the source modelling efforts. As data quality, computer power and speed are improving, it may be possible in the near future to decipher and accurately model tremor source processes at different volcanic environments. ß 2002 Elsevier Science B.V. All rights reserved.

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Seismic evolution of the 1989–1990 eruption sequence of Redoubt Volcano, Alaska

Cited by 125 publications

References 13 publications

Source constraints of Tungurahua volcano explosion events

Source constraints of Tungurahua volcano explosion events

New Methods and Future Trends in Seismological Volcano Monitoring

Nature, wavefield properties and source mechanism of volcanic tremor: a review

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