Seismoacoustic Recordings of Small Earthquakes in the Pyrenees: Experimental Results

Sylvander, Matthieu; Ponsolles, Christian; Benahmed, Sébastien; Fels, Jean-François

doi:10.1785/0120060009

Cited by 21 publications

(22 citation statements)

References 18 publications

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“…In section 5 we consider the The acoustic wavefield structure resulting from an impulsive shallow buried source is best illustrated in the 2-D simulation results of Figures 10, 12, and 13 (see also Movie S1). Two distinct acoustic arrivals result from this source configuration, in general agreement with the observations of Le Pichon et al [2002,2003], Mutschlecner and Whitaker [2005], and Sylvander et al [2007]. The first corresponds to locally converted P/SV and Rayleigh wave energy (identified by particle motion analysis, see Figure S4), and travels along the ground surface at seismic velocity, arriving at the infrasonic sensor coincident with the seismic energy.…”

Section: Point Sourcessupporting

confidence: 87%

“…Hence, the horizontal extent of the fluidfilled crack is neglected. In section 5 we consider the Sylvander et al [2007]. The first corresponds to locally converted P/SV and Rayleigh wave energy (identified by particle motion analysis, see Figure S4), and travels along the ground surface at seismic velocity, arriving at the infrasonic sensor coincident with the seismic energy.…”

Section: Point Sourcesmentioning

confidence: 99%

“…It is known that infrasound and acoustic gravity waves are generated by large tectonic earthquakes both from strong ground displacement and deformation near the source epicenter [e.g., Bolt, 1964;Mikumo, 1968], and interaction of surface waves with topography [Le Pichon et al, 2002, 2003, 2006Mutschlecner and Whitaker, 2005, and references therein]. In addition, P/SV and Rayleigh wave energy can be locally radiated into the atmosphere for even relatively small magnitude earthquakes [e.g., Press and Ewing, 1951;Kitov et al, 1997;Mutschlecner and Whitaker, 2005;Sylvander et al, 2007], providing an explanation for reports of low-frequency sounds accompanying earthquakes [Benioff et al, 1951]. Seismic-acoustic conversion is expected for LPs at Mount St. Helens because the source is very shallow ($200 m below the topography surface used in the moment tensor inversion), extended horizontally, and consists of a moment tensor with diagonal elements in the ratio M xx :M yy :M zz $ 1:1:3 [Waite et al, 2008], which propagates proportionally more energy vertically than horizontally.…”

Section: Introductionmentioning

confidence: 99%

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The source of infrasound associated with long‐period events at Mount St. Helens

Matoza¹,

Garcés²,

Chouet³

et al. 2009

J. Geophys. Res.

101

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[1] During the early stages of the [2004][2005][2006][2007][2008] Mount St. Helens eruption, the source process that produced a sustained sequence of repetitive long-period (LP) seismic events also produced impulsive broadband infrasonic signals in the atmosphere. To assess whether the signals could be generated simply by seismic-acoustic coupling from the shallow LP events, we perform finite difference simulation of the seismo-acoustic wavefield using a single numerical scheme for the elastic ground and atmosphere. The effects of topography, velocity structure, wind, and source configuration are considered. The simulations show that a shallow source buried in a homogeneous elastic solid produces a complex wave train in the atmosphere consisting of P/SV and Rayleigh wave energy converted locally along the propagation path, and acoustic energy originating from the source epicenter. Although the horizontal acoustic velocity of the latter is consistent with our data, the modeled amplitude ratios of pressure to vertical seismic velocity are too low in comparison with observations, and the characteristic differences in seismic and acoustic waveforms and spectra cannot be reproduced from a common point source. The observations therefore require a more complex source process in which the infrasonic signals are a record of only the broadband pressure excitation mechanism of the seismic LP events. The observations and numerical results can be explained by a model involving the repeated rapid pressure loss from a hydrothermal crack by venting into a shallow layer of loosely consolidated, highly permeable material. Heating by magmatic activity causes pressure to rise, periodically reaching the pressure threshold for rupture of the ''valve'' sealing the crack. Sudden opening of the valve generates the broadband infrasonic signal and simultaneously triggers the collapse of the crack, initiating resonance of the remaining fluid. Subtle waveform and amplitude variability of the infrasonic signals as recorded at an array 13.4 km to the NW of the volcano are attributed primarily to atmospheric boundary layer propagation effects, superimposed upon amplitude changes at the source.Citation: Matoza, R.

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Section: Point Sourcessupporting

confidence: 87%

Section: Point Sourcesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The source of infrasound associated with long‐period events at Mount St. Helens

Matoza¹,

Garcés²,

Chouet³

et al. 2009

J. Geophys. Res.

101

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“…Seismic motion mainly consists of frequency components below 10 Hz at most, whereas audible sound consists of frequency components from 20 Hz to 20 kHz. According to Hill et al (1976) and Sylvander et al (2007), elastic to acoustic transmission of SV waves for frequencies of a few tens of hertz gives a natural earthquake sound. However, the SH and surface waves, which produce the strongest shaking, are inaudible as any type of sound.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Earthquake-Like Sound Using Seismic Ground-Motion Records

Hirai¹,

Fukuwa²

2014

Bulletin of the Seismological Society of America

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Listening to a sound representing ground motion is valuable to intuitively understand an earthquake, compared with conventional methods such as observing waveforms, Fourier spectra, and response spectra. In this study, we propose a new method for generating sound representing an earthquake, which has several differences in comparison with existing methods. In our new method, an earthquake-like sound is generated by modifying the frequency information of a generating function based on the symmetric Fourier analysis theory. Applying the method to existing seismograms illustrates three features of the sound generated by this method: the sound has the same duration as the seismogram, the sound pitch corresponds to the instantaneous frequency of the seismogram, and the sound volume corresponds to the envelope amplitude of the seismogram. Furthermore, we constructed a web-based earthquake-like sound generating system called Naion. Other applications will be implemented in the future.

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“…Humans can hear sound waves mainly in the range of 20 to 20,000 Hz. The result is that only seismic waves with the highest pitch (mainly) reside in the frequency range for the lowest audible pitch, as confirmed by recordings of the sound accompanying small earthquakes indicating that the dominant frequencies were in the range of 5 to 60 Hz [ Sylvander et al , 2007]. The result explains why not all people in the same place hear seismic sounds and why some animals flee in fear.…”

Section: Introductionmentioning

confidence: 99%

Earthquake sound perception

Tosi

Sbarra

Rubeis

2012

Geophysical Research Letters

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[1] Sound is an effect produced by almost all earthquakes. Using a web-based questionnaire on earthquake effects that included questions relating to seismic sound, we collected 77,000 responses for recent shallow Italian earthquakes. An analysis of audibility attenuation indicated that the decrease of the percentage of respondents hearing the sound was proportional to the logarithm of the epicentral distance and linearly dependent on earthquake magnitude, in accordance with the behavior of ground displacement. Even if this result was based on Italian data, qualitative agreement with the results of theoretical displacement, and of a similar study based on French seismicity suggests wider validity. We also found that, given earthquake magnitude, audibility increased together with the observed macroseismic intensity, leading to the possibility of accounting for sound audibility in intensity assessment. Magnitude influenced this behavior, making small events easier to recognize, as suggested by their frequency content.

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Seismoacoustic Recordings of Small Earthquakes in the Pyrenees: Experimental Results

Cited by 21 publications

References 18 publications

The source of infrasound associated with long‐period events at Mount St. Helens

The source of infrasound associated with long‐period events at Mount St. Helens

Synthesis of Earthquake-Like Sound Using Seismic Ground-Motion Records

Earthquake sound perception

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