Tutorial on seismic interferometry: Part 1 — Basic principles and applications

[1] We estimate shear wave velocities in the shallow subsurface throughout Japan by applying seismic interferometry to the data recorded with KiK-net, a strong motion network in Japan. Each KiK-net station has two receivers; one receiver on the surface and the other in a borehole. By using seismic interferometry, we extract the shear wave that propagates between these two receivers. Applying this method to earthquake-recorded data at all KiK-net stations from 2000 to 2010 and measuring the arrival time of these shear waves, we analyze monthly and annual averages of the near-surface shear wave velocity all over Japan. Shear wave velocities estimated by seismic interferometry agree well with the velocities obtained from logging data. The estimated shear wave velocities of each year are stable. For the Niigata region, we observe a velocity reduction caused by major earthquakes. For stations on soft rock, the measured shear wave velocity varies with the seasons, and we show negative correlation between the shear wave velocities and precipitation. We also analyze shear wave splitting by rotating the horizontal components of the surface sensors and borehole sensors and measuring the dependence on the shear wave polarization. This allows us to estimate the polarization with the fast shear wave velocity throughout Japan. For the data recorded at the stations built on hard rock sites, the fast shear wave polarization directions correlate with the direction of the plate motion.Citation: Nakata, N., and R. Snieder (2012), Estimating near-surface shear wave velocities in Japan by applying seismic interferometry to KiK-net data,

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“…[11] The cross-correlation approach to retrieve the wavefield in one dimension is given by Wapenaar et al [2010]:…”

Section: Retrieval Of the Wavefield Between Receiversmentioning

confidence: 99%

Estimating near‐surface shear wave velocities in Japan by applying seismic interferometry to KiK‐net data

2012

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“…This principle has been successfully applied in the fields of ultrasonics [7], regional seismology [8,9,10,11], exploration seismic [12], underwater acoustics [13,14], and medical imaging [15]. For a review of the theory and the many applications see [16], [17], [18], and [19].…”

Section: Introductionmentioning

confidence: 99%

On the Retrieval of the Directional Scattering Matrix from Directional Noise

Wapenaar¹,

Thorbecke²

2013

SIAM J. Imaging Sci.

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Abstract. The crosscorrelation of ambient acoustic noise observed at two receivers yields the impulse response between these receivers, assuming that the noise field is diffuse. In practical situations the noise field exhibits directionality, which imprints the angle-dependent correlation function. For the situation of a directional scatterer in a directional noise field, the correlation function contains the product of the directional scattering matrix and the directional noise. This seemingly underdetermined problem can be resolved by exploiting a relation between the causal and acausal parts of the correlation function. For a given pair of receivers, the causal and acausal parts of the correlation function contain the same element of the scattering matrix (by reciprocity) but different elements of the directional noise field. This property can be used to estimate the directionality of the noise (apart from an undetermined scaling factor) and, subsequently, of the scattering matrix.

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“…2), and autocorrelation for all stations. The cross-correlation can be considered as the Green's function where one source acts as a virtual source (Wapenaar et al, 2010). For the autocorrelation, the virtual source is located at the same station.…”

Section: Data and Processingmentioning

confidence: 99%

Temporal seismic wave velocity variations at Láscar volcano

González

Bataille

Eulenfeld

et al. 2016

andgeo

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ABSTRACT. We report on the first study using Seismic Wave Interferometry to determine variations of seismic velocities through time, in the vicinity of Láscar volcano in Chile. Seismic Wave Interferometry has been used as a powerful tool to determine spatial and temporal changes of seismic velocities within the Earth. Spatial variations of seismic velocities are related to heterogeneities of material properties, which are expected to occur in a complex structure. However, temporal changes are indicative of dynamic process within the elastic media, and thus, this tool can be used to monitor dynamic processes at volcanic zones. We find consistent variations on three stations close to the volcano, with dv/v of ±0.6%, most likely related to the inflation/deflation process due to fluid movement of magmatic or hydrothermal origin within the volcanic structure. During the observed period of velocity variation, OVDAS reported an increase of volcanic activity evidenced by the increase of the number of long period seismic events, increase of gas emissions and the formation of incandescence above the crater. We suggest that this tool can contribute to the understanding of volcano related dynamic processes, as well as for routine volcano monitoring purposes. RESUMEN. Variaciones temporales de velocidad de ondas sísmicas en el volcán Láscar.Reportamos el primer estudio utilizando Interferometría Sísmica Pasiva para determinar las variaciones de la velocidad de ondas sísmicas en función del tiempo, en las cercanías del volcán Láscar, Chile. La Interferometría Sísmica Pasiva ha sido utilizada como una poderosa herramienta para determinar cambios espaciales y temporales en la velocidad de ondas sísmicas a través de la Tierra. Las variaciones espaciales están relacionadas con las heterogeneidades en las propiedades del material, las cuales se esperan observar en una estructura compleja. Sin embargo, los cambios temporales son un indicativo de los procesos dinámicos que ocurren en un medio elástico, y así esta herramienta puede ser utilizada para monitorear los procesos dinámicos en zonas volcánicas. Encontramos variaciones consistentes en tres estaciones cercanas al volcán, con un dv/v cercano a ±0.6 km/s, asociado a un proceso de inflación/deflación debido al movimiento de fluidos de origen magmático o hidrotermal en la estructura volcánica. Durante el período de observación de los cambios de velocidad, OVDAS reportó un incremento en la actividad volcánica evidenciado por un aumento en el número de eventos de largo período, alza en la emisión de gases e incandescencia en el cráter del volcán. Sugerimos que esta herramienta puede contribuir al conocimiento sobre los procesos dinámicos en volcanes, como también una rutina con propósitos de monitoreo. et al. / Andean Geology 43 (2): 240-246, 2016 González

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Tutorial on seismic interferometry: Part 1 — Basic principles and applications

Cited by 347 publications

References 116 publications

Estimating near‐surface shear wave velocities in Japan by applying seismic interferometry to KiK‐net data

Estimating near‐surface shear wave velocities in Japan by applying seismic interferometry to KiK‐net data

On the Retrieval of the Directional Scattering Matrix from Directional Noise

Temporal seismic wave velocity variations at Láscar volcano

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