Magnitude determination of deep-focus earthquakes in and around Japan with regional velocity-amplitude data

Katsumata, Akio

doi:10.1186/bf03352390

Cited by 10 publications

(15 citation statements)

References 27 publications

(42 reference statements)

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“…The major difference between tectonic tremor and intraslab earthquakes in Nankai is the source depth, so it is likely that the material at depths between the tremor event hypocenters and intraslab earthquake hypocenters has a characteristic attenuation that affects our estimation of C. Based on this idea, we construct a simple layered attenuation structure (Fig. 11a) Attenuation structure (Katsumata, 2001) Q s =500…”

Section: Synthetic Tests For Distance Dependent Attenuationmentioning

confidence: 99%

“…Furthermore, 1% of PGV are replaced by a random value from 100 to 1600 nm=s, which captures the effect of random noise. Figure 10a shows the synthetic PGV data generated using the attenuation structure of Katsumata (2001), the estimated C and site factors for the different distance limits, and synthetic path-averaged attenuation for specific hypocentral distance. The site factors are stable and well reproduced in this estimation.…”

Section: Synthetic Tests For Distance-dependent Attenuationmentioning

confidence: 99%

“…We consider two different attenuation structures to determine if the observed distance-dependent C is due to a layered attenuation model. The first, a reference model, is that of Katsumata (2001), which represents the average attenuation structure in Japan. In this model, the upper layer, with a thickness of 20 km and shear-wave attenuation, Q S of 500, is less attenuating than the lower layer, with a thickness of 10 km and Q S 100 (Fig.…”

Section: Synthetic Tests For Distance-dependent Attenuationmentioning

confidence: 99%

“…nearly lossless) from 35 to 40 km depth to simulate the subducting oceanic mantle (Katsumata, 2001). The S-wave velocity in the attenuating layer (between 30 and 35 km depth) is set at 3:6 km=s (about a 10% reduction from the JMA 2001; Hirose et al, 2008).…”

Section: Synthetic Tests For Distance Dependent Attenuationmentioning

confidence: 99%

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Seismic-Wave Attenuation Determined from Tectonic Tremor in Multiple Subduction Zones

Yabe¹,

Baltay²,

Ide³

et al. 2014

Bulletin of the Seismological Society of America

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Tectonic tremor provides a new source of observations that can be used to constrain the seismic attenuation parameter for ground-motion prediction and hazard mapping. Traditionally, recorded earthquakes of magnitude ∼3-8 are used to develop ground-motion prediction equations; however, typical earthquake records may be sparse in areas of high hazard. In this study, we constrain the distance decay of seismic waves using measurements of the amplitude decay of tectonic tremor, which is plentiful in some regions. Tectonic tremor occurs in the frequency band of interest for ground-motion prediction (i.e., ∼2-8 Hz) and is located on the subducting plate interface, at the lower boundary of where future large earthquakes are expected. We empirically fit the distance decay of peak ground velocity from tremor to determine the attenuation parameter in four subduction zones: Nankai, Japan; Cascadia, United States-Canada; Jalisco, Mexico; and southern Chile. With the large amount of data available from tremor, we show that in the upper plate, the lower crust is less attenuating than the upper crust. We apply the same analysis to intraslab events in Nankai and show the possibility that waves traveling from deeper intraslab events experience more attenuation than those from the shallower tremor due to ray paths that pass through the subducting and highly attenuating oceanic crust. This suggests that high pore-fluid pressure is present in the tremor source region. These differences imply that the attenuation parameter determined from intraslab earthquakes may underestimate ground motion for future large earthquakes on the plate interface.

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Section: Synthetic Tests For Distance Dependent Attenuationmentioning

confidence: 99%

Section: Synthetic Tests For Distance-dependent Attenuationmentioning

confidence: 99%

Section: Synthetic Tests For Distance-dependent Attenuationmentioning

confidence: 99%

Section: Synthetic Tests For Distance Dependent Attenuationmentioning

confidence: 99%

See 2 more Smart Citations

Seismic-Wave Attenuation Determined from Tectonic Tremor in Multiple Subduction Zones

Yabe¹,

Baltay²,

Ide³

et al. 2014

Bulletin of the Seismological Society of America

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“…The intrinsic attenuation factor of Q = 184 is used. This quality factor is calculated on the basis of the depth‐dependent attenuation model in Japan of Katsumata [2001] by assuming the average depth of a tremor to be 35 km. The weight factor of the amplitude analysis at the i th station is set as the average of the maximum correlation function among the pairs, including the i th station, and these values are larger than 0.7.…”

Section: Estimating Tremor Source Location and Seismic Energymentioning

confidence: 99%

Spatiotemporal distribution of seismic energy radiation from low‐frequency tremor in western Shikoku, Japan

2009

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[1] The spatiotemporal patterns of the radiated seismic energy from low-frequency tremor associated with slow slip events in western Shikoku, Japan, have been estimated. A spatially decaying mean square amplitude and differential traveltime measurement from envelope correlations observed at Hi-net stations were used to locate tremors and to estimate their seismic energies. Tremor amplitude was corrected for the site amplification factors estimated using the coda normalization method. The location of the tremor is estimated as the position where both the decay of the observed energy and the differential travel times are well explained. The temporal pattern of the total energy released agrees very well with the observed tilt records. Although the spatial patterns of the energy radiation vary strongly among the six slow slip events (SSEs) in western Shikoku, the region where they overlap always radiates relatively high levels of energy. The estimated band-limited energy rate of the tremor for a 2 to 10 Hz bandwidth was typically between 10 5 and 10 6 J/min, though there is temporal variation of the radiation energy. The released total energy associated with the SSEs whose magnitude is 5.9-6.1 is on the order of 10 8 J within the duration of SSEs of 8-13 days. This is quite small energy radiation compared to the moment release of accompanying SSE. The scaled energy, which is the ratio of the seismic moment and the seismic energy, for the slow slip and a very low frequency earthquake was estimated to be 5 orders of magnitude smaller than that of a regular earthquake.Citation: Maeda, T., and K. Obara (2009), Spatiotemporal distribution of seismic energy radiation from low-frequency tremor in western Shikoku, Japan,

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Magnitude Measures

Giles

2013

Encyclopedia of Earth Sciences Series

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Magnitude determination of deep-focus earthquakes in and around Japan with regional velocity-amplitude data

Cited by 10 publications

References 27 publications

Seismic-Wave Attenuation Determined from Tectonic Tremor in Multiple Subduction Zones

Seismic-Wave Attenuation Determined from Tectonic Tremor in Multiple Subduction Zones

Spatiotemporal distribution of seismic energy radiation from low‐frequency tremor in western Shikoku, Japan

Magnitude Measures

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