Time reversal and the spatio-temporal matched filter (L)

Time-reversal invariance can be exploited in wave physics to control wave propagation in complex media. Because time and space play a similar role in wave propagation, time-reversed waves can be obtained by manipulating spatial boundaries or by manipulating time boundaries. The two dual approaches will be discussed in this paper. The first approach uses ‘time-reversal mirrors’ with a wave manipulation along a spatial boundary sampled by a finite number of antennas. Related to this method, the role of the spatio-temporal degrees of freedom of the wavefield will be emphasized. In a second approach, waves are manipulated from a time boundary and we show that ‘instantaneous time mirrors’, mimicking the Loschmidt point of view, simultaneously acting in the entire space at once can also radiate time-reversed waves.

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Range imaging based on moving pattern light and spatio-temporal matched filter

Proceedings of 3rd IEEE International Conference on Image Processing ◽

10.1109/icip.1996.559426 ◽

2002 ◽

Cited By ~ 7

Author(s):

K. Sato

Keyword(s):

Matched Filter ◽

Range Imaging ◽

Spatio Temporal ◽

Moving Pattern

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Comparison between time reversal and spatio‐temporal inverse filter application to focusing through a human skull

The Journal of the Acoustical Society of America ◽

10.1121/1.4744461 ◽

2001 ◽

Vol 109 (5) ◽

pp. 2397-2397

Author(s):

Mickael Tanter ◽

Jean‐Francois Aubry ◽

Jean‐Louis Thomas ◽

Mathias Fink

Keyword(s):

Time Reversal ◽

Inverse Filter ◽

Human Skull ◽

Spatio Temporal

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Detection of Deep Low-frequency Earthquakes in the Nankai Subduction Zoneover 11 Years Usingamatched Filter Technique

10.21203/rs.3.rs-37377/v1 ◽

2020 ◽

Author(s):

Aitaro Kato ◽

Shigeki Nakagawa

Keyword(s):

Matched Filter ◽

Low Frequency ◽

Slow Slip ◽

Slow Slip Events ◽

Filter Technique ◽

Strike Direction ◽

Episodic Tremor And Slip ◽

Spatio Temporal ◽

Episodic Tremor

Abstract To improve our understanding of the long-term behavior of low-frequency earthquakes (LFEs) along the tremor belt of the Nankai subduction zone, we applied a matched filter technique to continuous seismic data recorded by a dense and highly sensitive seismic network over an 11year window, April 2004 to August 2015. We detected a total of ~510,000 LFEs, or ~23× the number of LFEs in the JMA catalog for the same period. During long-term slow slip events (SSEs) in the Bungo Channel, a series of migrating LFEbursts intermittently occurred along the fault-strike direction, with slow hypocenter propagation. Elastic energy released by long-term SSEs appears to control the extent of LFE activity. We identify slowlymigrating fronts of LFEs during major episodic tremor and slip (ETS)events, which extend over distances of up to 100 km and follow diffusion-like patterns of spatial evolution with a diffusion coefficient of ~104 m2/s. This migration pattern closely matches the spatio-temporal evolution of tectonictremors reported by previous studies. At shorter distances, up to 15 km, we discovered rapid diffusion-like migrationof LFEs with a coefficient of ~105 m2/s. We also recognize that rapid migration of LFEs occurred intermittently in many streaks during major ETS episodes. These observations suggest that slow slip transients contain a multitude of smaller, temporally clustered fault slip events whose evolution is controlled by a diffusional process.

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Detection of deep low-frequency earthquakes in the Nankai subduction zone over 11 years using a matched filter technique

10.21203/rs.3.rs-37377/v2 ◽

2020 ◽

Author(s):

Aitaro Kato ◽

Shigeki Nakagawa

Keyword(s):

Subduction Zone ◽

Matched Filter ◽

Low Frequency ◽

Slow Slip ◽

Slow Slip Events ◽

Filter Technique ◽

Episodic Tremor And Slip ◽

Nankai Subduction Zone ◽

Spatio Temporal

Abstract To improve our understanding of the long-term behavior of low-frequency earthquakes (LFEs) along the tremor belt of the Nankai subduction zone, we applied a matched filter technique to continuous seismic data recorded by a dense and highly sensitive seismic network over an 11 year window, April 2004 to August 2015. We detected a total of ~510,000 LFEs, or ~23× the number of LFEs in the JMA catalog for the same period. During long-term slow slip events (SSEs) in the Bungo Channel, a series of migrating LFE bursts intermittently occurred along the fault-strike direction, with slow hypocenter propagation. Elastic energy released by long-term SSEs appears to control the extent of LFE activity. We identify slowly migrating fronts of LFEs during major episodic tremor and slip (ETS) events, which extend over distances of up to 100 km and follow diffusion-like patterns of spatial evolution with a diffusion coefficient of ~10 4 m 2 /s. This migration pattern closely matches the spatio-temporal evolution of tectonic tremors reported by previous studies. At shorter distances, up to 15 km, we discovered rapid diffusion-like migration of LFEs with a coefficient of ~10 5 m 2 /s. We also recognize that rapid migration of LFEs occurred intermittently in many streaks during major ETS episodes. These observations suggest that slow slip transients contain a multitude of smaller, temporally clustered fault slip events whose evolution is controlled by a diffusional process.

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