Joint analysis of infrasound and seismic signals by cross wavelet transform: detection of Mt. Etna explosive activity

Cannata, Andrea; Montalto, P.; Patané, Domenico

doi:10.5194/nhess-13-1669-2013

Cited by 26 publications

(22 citation statements)

References 40 publications

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“…Furthermore, because the eruption involves fluid-solid interactions, we conclude that the dipolar sources, likely distributed spatially, are dominant in our near field recordings. Similar correlations where found by Cannata et al (2013) studying paroxysms of Etna volcano. They found correlations over 70-75 per cent between the root mean square (RMS) of amplitudes of seismic and acoustic records, within a similar seismic frequency range (0.5-5.5 Hz) to our case, and in the near field also.…”

Section: O N C L U S I O N Ssupporting

confidence: 83%

Seismic-acoustic energy partitioning during a paroxysmal eruptive phase of Tungurahua volcano, Ecuador

Palacios

Dı́ez

Kendall

et al. 2016

Geophysical Journal International

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S U M M A R YStudies of discrete volcanic explosions, that usually last less than 2 or 3 min, have suggested that the partitioning of seismic-acoustic energy is likely related to a range of physical mechanisms that depend on magma properties and other physical constraints such as the location of the fragmentation surface. In this paper, we explore the energy partition of a paroxysmal eruptive phase of Tungurahua volcano that lasted for over 4 hr, on 2006 July 14-15, using seismicacoustic information recorded by stations on its flanks (near field). We find evidence of a linear scaling between seismic and acoustic energies, with time-dependent intensities, during the sustained explosive phase of the eruption. Furthermore, we argue that this scaling can be explained by two different processes: (1) the fragmentation region ultimately acts as the common source of energy producing both direct seismic waves, that travel through the volcanic edifice, and direct acoustic waves coming from a disturbed atmosphere above the summit; (2) the coupling of acoustic waves with the ground to cause seismic waves. Both processes are concurrent, however we have found that the first one is dominant for seismic records below 4 Hz. Here we use the linear scaling of intensities to construct seismic and acoustic indices, which, we argue, could be used to track an ongoing eruption. Thus, especially in strong paroxysms that can produce pyroclastic flows, the index correlation and their levels can be used as quantitative monitoring parameters to assess the volcanic hazard in real time. Additionally, we suggest from the linear scaling that the source type for both cases, seismic and acoustic, is dipolar and dominant in the near field.

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Section: O N C L U S I O N Ssupporting

confidence: 83%

Seismic-acoustic energy partitioning during a paroxysmal eruptive phase of Tungurahua volcano, Ecuador

Palacios

Dı́ez

Kendall

et al. 2016

Geophysical Journal International

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“…A similar coherence analysis was for instance performed by Cannata et al (2013) using cross wavelet transform for detecting explosive activity at Etna volcano. The principal difference with the present study lies in the usage of stations much closer to the active vent (∼1-1.7 km) and the strong intensity of the explosive activity, the combination of which leads to high signal-to-noise ratio for both seismic and infrasonic records.…”

Section: Resultsmentioning

confidence: 99%

Single-Station Seismo-Acoustic Monitoring of Nyiragongo's Lava Lake Activity (D.R. Congo)

et al. 2018

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Since its last effusive eruption in 2002, Nyiragongo has been an open-vent volcano characterized by the world's largest persistent lava lake. This lava lake provides a unique opportunity to detect pressure change in the magmatic system by analyzing its level fluctuations. We demonstrate that this information is contained in the seismic and infrasound signals generated by the lava lake's activity. The continuous seismo-acoustic monitoring permits quantification of lava lake dynamics, which is analyzed retrospectively to identify periods of volcanic unrest. Synchronous, high-resolution satellite SAR (Synthetic Aperture Radar) images are used to constrain lava lake level by measuring the length of the SAR shadow cast by the rim of the pit crater where the lava lake is located. Seventy-two estimations of the lava lake level were obtained with this technique between August 2016 and November 2017. These sporadic measurements allow for a better interpretation of the continuous infrasound and seismic data recorded at the closest station (∼6 km from the crater). Jointly analyzed seismo-acoustic and SAR data reveal that slight changes in the spectral properties of the continuous cross-correlated low-frequency seismo-acoustic records (and not solely single events) can be used to track fluctuations of the lava lake level on a daily and hourly basis. We observe that drops of the lava lake and the appearance of significant long period (LP) "lava lake" events are a consequence of a probable deep lateral magma intrusion beneath Nyiragongo, which induces changes in its shallow plumbing system. In addition to contributing to understanding lava lake dynamics, this study highlights the potential to continuously monitor pressure fluctuations within the magmatic system using a single seismo-acoustic station located several kilometers from the vent.

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“…Therefore, unless a large number of band passes are systematically searched, there is the potential to miss narrowband correlations between seismic and infrasonic waveforms that are otherwise uncorrelated at other frequencies. A significant practical advantage is thus made by also working in the frequency domain and using coherence in addition to cross correlation (see also the papers by Sciotto et al [] and Cannata et al [], who use coherence and wavelet transform coherence, respectively). We use the coherence (magnitude‐squared coherence) between unfiltered seismic and acoustic waveforms:

γ_{wp}^{2} = \frac{| S_{wp} |^{2}}{S_{ww} S_{pp}},

where S w w and S p p are the power spectra of vertical seismic velocity and acoustic pressure, respectively, and S w p is the cross spectrum.…”

Section: Methodsmentioning

confidence: 99%

Infrasonic component of volcano-seismic eruption tremor

Matoza

Fee

2014

Geophys. Res. Lett.

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Air-ground and ground-air elastic wave coupling are key processes in the rapidly developing field of seismoacoustics and are particularly relevant for volcanoes. During a sustained explosive volcanic eruption, it is typical to record a sustained broadband signal on seismometers, termed eruption tremor. Eruption tremor is usually attributed to a subsurface seismic source process, such as the upward migration of magma and gases through the shallow conduit and vent. However, it is now known that sustained explosive volcanic eruptions also generate powerful tremor signals in the atmosphere, termed infrasonic tremor. We investigate infrasonic tremor coupling down into the ground and its contribution to the observed seismic tremor. Our methodology builds on that proposed by Ichihara et al. (2012) and involves cross-correlation, coherence, and cross-phase spectra between waveforms from nearly collocated seismic and infrasonic sensors; we apply it to datasets from Mount St. Helens, Tungurahua, and Redoubt Volcanoes.

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Joint analysis of infrasound and seismic signals by cross wavelet transform: detection of Mt. Etna explosive activity

Cited by 26 publications

References 40 publications

Seismic-acoustic energy partitioning during a paroxysmal eruptive phase of Tungurahua volcano, Ecuador

Seismic-acoustic energy partitioning during a paroxysmal eruptive phase of Tungurahua volcano, Ecuador

Single-Station Seismo-Acoustic Monitoring of Nyiragongo's Lava Lake Activity (D.R. Congo)

Infrasonic component of volcano-seismic eruption tremor

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