Interference of long-period seismic wavefield observed by the dense Hi-net array in Japan

Maeda, Takuto; Obara, Kazushige; Furumura, Takashi; Saito, Tatsuhiko

doi:10.1029/2011jb008464

Cited by 55 publications

(40 citation statements)

References 28 publications

(34 reference statements)

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“…In this respect, the Hi-net data were processed using the approach of Maeda et al (2011), who showed that the Hi-net waveforms can be successfully used to retrieve long-period ground motions after applying an appropriately designed recursive filter.…”

Section: Methodsmentioning

confidence: 99%

Remote triggering of seismicity at Japanese volcanoes following the 2016 M7.3 Kumamoto earthquake

Enescu

Shimojo

Opris

et al. 2016

Earth Planets Space

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The M JMA 7.3 Kumamoto earthquake occurred on April 16, 2016, in the western part of Kyushu, at a depth of 12 km, on an active strike-slip fault. Here, we report on a relatively widespread activation of small remote earthquakes, which occurred as far as Hokkaido, detected by analyzing the continuous waveform data recorded at seismic stations all over Japan. Such relatively widespread remote seismicity activation, following a large inland earthquake, has not been reported before for Japan. Our analysis demonstrates that the remote events were triggered dynamically, by the passage of the surface waves from the Kumamoto earthquake. Most of the remotely triggered events in the Tohoku and Hokkaido regions, as well as close to Izu Peninsula, occur at or close to volcanoes, which suggests that the excitation of crustal fluids, by the passage of Rayleigh waves, played an important triggering role. Nevertheless, remote activation in other regions, like Noto Peninsula, occurred away from volcanoes. The relatively large-amplitude Love waves, enhanced by a source directivity effect during the Kumamoto earthquake, may have triggered seismicity on local active faults. The dynamic stresses in the areas where remote activation has been observed range from several kPa to tens of kPa, the thresholds being lower than in previous dynamic triggering cases for Japan; this might relate to a change in the crustal conditions following the 2011 M9.0 Tohoku-oki earthquake, in particular at volcanoes in NE Japan.

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Section: Methodsmentioning

confidence: 99%

Remote triggering of seismicity at Japanese volcanoes following the 2016 M7.3 Kumamoto earthquake

Enescu

Shimojo

Opris

et al. 2016

Earth Planets Space

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“…We used the unified hypocentral catalog provided by the Japan Meteorological Agency (JMA), which is available via the JMA server. The frequency response of the short-period Hi-net sensors with a natural frequency of 1 Hz was corrected to make a broadband record using the program of Maeda et al (2011). Generic Mapping Tools (Wessel and Smith 1998) and Seismic Analysis Code (SAC) were used for making the figures…”

Section: Acknowledgementsmentioning

confidence: 99%

Prediction of maximum P- and S-wave amplitude distributions incorporating frequency- and distance-dependent characteristics of the observed apparent radiation patterns

Takemura

Kobayashi

Yoshimoto

2016

Earth Planets Space

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Frequency-dependent model of the apparent radiation pattern has been extensively incorporated into engineering and scientific applications for high-frequency seismic waves, but distance-dependent properties have not yet been fully taken into account. We investigated the unified characteristics of frequency and distance dependences in both apparent P-and S-wave radiation patterns during local crustal earthquakes. Observed distortions of the apparent Pand S-wave radiation patterns could be simply modeled by using a function of the normalized hypocentral distance, which is a product of the wave number and hypocentral distance. This behavior suggests that major cause of distortion of the apparent radiation pattern is seismic wave scattering and diffraction within the heterogeneous crust. On the basis of observed normalized hypocentral distance dependency, we proposed a method for prediction of spatial distributions of maximum P-and S-wave amplitudes. Our method incorporating normalized hypocentral distance dependence of the apparent radiation pattern reproduced the observed spatial distributions of maximum P-and S-wave amplitudes over a wide frequency and distance ranges successfully.

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“…Each Hi-net station consists of three-component velocity-type seismometers with a natural frequency of 1 Hz installed in a borehole. Each velocity seismogram was corrected for the frequency response of the Hi-net borehole sensors (Maeda et al 2011). Based on the observations by Hori (1990Hori ( , 2006, we selected seven earthquakes occurring at depths of 50 to 60 km near the oceanic crust of (Hirose et al 2008a) are shown for 10 km intervals in (a).…”

Section: Data and Analysis Methods For The Observed Seismogramsmentioning

confidence: 99%

Velocity increase in the uppermost oceanic crust of subducting Philippine Sea plate beneath the Kanto region due to dehydration inferred from high-frequency trapped P waves

2015

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To investigate the detailed structural properties of the oceanic crust of subducting oceanic plate, we analyzed high-frequency (1 to 16 Hz) trapped P waves during earthquakes that occurred near the oceanic crust of the Philippine Sea plate. The distinct trapped P waves observed by the dense seismic network of the Kanto-Tokai region, Japan, did not show any apparent peak delay and frequency-dependent dispersion. These observations suggested that the oceanic crust around the source depths was characterized by a homogeneous velocity structure, rather than an inhomogeneous multiple-layered structure. This interpretation was examined by finite difference method simulations of seismic wave propagation using possible velocity structure models. The simulations demonstrated that a uniform velocity oceanic crust of the subducting Philippine Sea plate, which may result from the velocity increase in this layer at 30 to 40 km depth due to metamorphic-dehydration reactions, effectively trapped seismic energy as a short-distance waveguide and developed distinct pulse-like trapped P waves.

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Interference of long-period seismic wavefield observed by the dense Hi-net array in Japan

Cited by 55 publications

References 28 publications

Remote triggering of seismicity at Japanese volcanoes following the 2016 M7.3 Kumamoto earthquake

Remote triggering of seismicity at Japanese volcanoes following the 2016 M7.3 Kumamoto earthquake

Prediction of maximum P- and S-wave amplitude distributions incorporating frequency- and distance-dependent characteristics of the observed apparent radiation patterns

Velocity increase in the uppermost oceanic crust of subducting Philippine Sea plate beneath the Kanto region due to dehydration inferred from high-frequency trapped P waves

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