Locating the Tohoku-Oki 2011 tsunami source using acoustic–gravity waves

Raveloson, A.; Kind, R.; Yuan, Xiaohui; Ceranna, Lars

doi:10.1007/s10950-011-9262-7

Cited by 3 publications

(3 citation statements)

References 7 publications

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“…So far, observation of the Tohoku neutral waves has been limited to the detection of gravito‐acoustic waves with micro‐barometers [ Arai et al , ; Raveloson et al , ]. We present here the first direct observation of post‐seismic neutral acoustic waves in the thermosphere, along the GOCE orbit.…”

Section: Introductionmentioning

confidence: 88%

GOCE: The first seismometer in orbit around the Earth

Garcia

Bruinsma²,

Lognonné

et al. 2013

Geophysical Research Letters

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[1] The first in situ sounding of a post-seismic infrasound wavefront is presented, using data from the GOCE mission. The atmospheric infrasounds following the great Tohoku earthquake (on 11 March 2011) induce variations of air density and vertical acceleration of the GOCE platform. These signals are detected at two positions along the GOCE orbit corresponding to a crossing and a doubling of the infrasonic wavefront created by seismic surface waves. Perturbations up to 11% of air density and 1.35 10 -7 m/s 2 of vertical acceleration are observed and modeled with two different solid-atmosphere coupling codes. These perturbations are a due to acoustic waves creating vertical velocities up to 130 m/s. Amplitudes and arrival times of these perturbations are reproduced respectively within a factor 2, and within a 60 s time window. Waveforms present a good agreement with observed data. The vertical acceleration to air density perturbation ratio is higher for these acoustic waves than for gravity waves. Combining these two pieces of information offers a new way to distinguish between these two wave types. This new type of data is a benchmark for the models of solid-atmosphere coupling. Amplitude and frequency content constrain the infrasound attenuation related to atmosphere viscosity and thermal conductivity. Observed time shifts between data and synthetics are ascribed to lateral variations of the seismic and atmospheric sound velocities and to the influence of atmospheric winds. These effects should be included in future modeling. This validation of our modeling tools allows to specify more precisely future observation projects.

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Section: Introductionmentioning

confidence: 88%

GOCE: The first seismometer in orbit around the Earth

Garcia

Bruinsma²,

Lognonné

et al. 2013

Geophysical Research Letters

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“…[9] The Earth's surface is a speaker [Rayleigh, 1945]. Seismic shaking of the surface generates sound spanning the audible and infrasonic frequency ranges.…”

Section: Radiation Of Infrasound From Surface Shakingmentioning

confidence: 99%

“…Areas of high-frequency seismic radiation occurred near the western edges of the rupture plane closest to Sendai [Simons et al, 2011]. Several studies have found evidence for long-period infrasound or gravity waves generated from uplift in the source region [Arai et al, 2011;Nishitani et al, 2011;Chum et al, 2012;Raveloson et al, 2012;Garcia et al, 2013].…”

Section: Tohoku Earthquakementioning

confidence: 99%

An analysis of ground shaking and transmission loss from infrasound generated by the 2011 Tohoku earthquake

et al. 2013

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[1] The 2011 M w 9.0 Tohoku earthquake generated infrasound that was recorded by nine infrasonic arrays. Most arrays recorded a back azimuth variation with time due to the expanse of the source region. We use ray tracing to predict group velocities and back azimuth wind corrections. A Japan accelerometer network recorded ground shaking in unprecedented spatial resolution. We back projected infrasound from arrays IS44 (Kamchatka) and IS30 (Tokyo) to the source region and compare these results with acceleration data. IS44 illuminates the complex geometry of land areas that experienced shaking. IS30 illuminates two volcanoes and a flat area around the city of Sendai, where the maximum accelerations occurred. The arrays and epicentral region define three source-receiver profiles. The observed broadband energy transmission loss (TL) follows an exponential decay law. The best fitting model, which has parameters that are interpreted to include the effects of geometric spreading, scattering, and the maximum ratio of the effective sound speed in the stratosphere to that at the ground (accounts for stratospheric wind speed), yields a 65% variance reduction relative to predictions from a traditional TL relationship. This model is a simplified version of the model of Le Pichon et al. (2012), which yields an 83% variance reduction for a single frequency, implying that fine-scale atmospheric structure is required to explain the TL for stratospheric upwind propagation. Our results show that infrasonic arrays are sensitive to ground acceleration in the source region of megathrust earthquakes. The TL results may improve infrasonic amplitude scaling laws for explosive yield.

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