scholarly journals Source model for strong ground motion generation in the frequency range 0.1–10 Hz during the 2011 Tohoku earthquake

2012 ◽  
Vol 64 (12) ◽  
pp. 1111-1123 ◽  
Author(s):  
Kimiyuki Asano ◽  
Tomotaka Iwata
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Tohoku Earthquake ◽  
Source Model ◽  
2011 Tohoku Earthquake ◽  
Frequency Range ◽  
Motion Generation ◽  
The 2011 Tohoku Earthquake ◽  
Strong Ground

High-Frequency Spectral Decay Characteristics of Seismic Records of Inland Crustal Earthquakes in Japan: Evaluation of the fmax and κ Models

2020 ◽  
Vol 110 (2) ◽  
pp. 452-470
Author(s):  
Masato Tsurugi ◽  
Reiji Tanaka ◽  
Takao Kagawa ◽  
Kojiro Irikura
Keyword(s):  
Ground Motion ◽  
High Frequency ◽  
Strong Ground Motion ◽  
Cutoff Frequency ◽  
Source Model ◽  
Power Coefficient ◽  
Crustal Earthquakes ◽  
Log Linear ◽  
Large Earthquakes ◽  
Strong Ground

ABSTRACT We examined high-frequency spectral decay characteristics of ground motions for inland crustal earthquakes in Japan, which are important in strong ground motion predictions. We examined 105 earthquakes (Mw 3.3–7.1), including seven large earthquakes (Mw 5.9–7.1). Spectral decay characteristics were accurately evaluated assuming the ω-squared source model and using two approaches: the fmax model (commonly used in Japan), described by the cutoff frequency fmax and the power coefficient of spectral decay s, and the κ model (commonly used in worldwide), the exponential spectral decay model, described by the parameter κ and the specific frequency fE at which a spectrum starts to decrease linearly with increasing frequency in log–linear space. For large earthquakes, we estimated fmax to range from 6.5 to 9.9 Hz and s from 0.78 to 1.60 in the fmax model, and κ to range from 0.014 to 0.051 s and fE from 2 to 4.5 Hz in the κ model. In both approaches, we found that the spectral decay characteristics are regionally dependent. fmax in the fmax model and fE in the κ model tended to be smaller for large earthquakes than for moderate and small earthquakes, clearly demonstrating a seismic moment dependency. We confirmed positive correlations between equivalent parameters of the two approaches, that is, between s and κ and between fmax and fE. Moreover, we found that both approaches are appropriate for evaluating spectral decay characteristics, as long as the spectral decay parameters are appropriately evaluated by comparison with observed spectra. We examined the effects of the spectral decay characteristics on strong ground motion predictions, and demonstrated that simulated motions corrected using the fmax model and those corrected using the κ model are almost the same. The results presented in this article contribute to improving predictions of high-frequency strong ground motion.

Strong Motion Records of the 2011 Tohoku Earthquake and its Attenuation Characteristics

2012 ◽  
Vol 7 (6) ◽  
pp. 693-700 ◽  
Author(s):  
Saburoh Midorikawa ◽  
◽  
Hiroyuki Miura ◽  
Tomohiro Atsumi
Keyword(s):  
Ground Motion ◽  
Strong Motion ◽  
Tohoku Earthquake ◽  
Distribution Model ◽  
Motion Generation ◽  
The 2011 Tohoku Earthquake ◽  
Strong Motion Records ◽  
Attenuation Relationships ◽  
Shortest Distance ◽  
Definition Of

Many strong motion records were obtained during the 2011 Off the Pacific Coast of Tohoku earthquake owing to the implementation of dense strong motion observation in Japan. The earthquake provides an opportunity to examine the characteristics of strong ground motion from a gigantic earthquake. Attenuations of peak acceleration and velocity are examined by comparing them to curves from existing attenuation relationships. When the shortest distance from the fault plane of the slip distribution model is used, curves for Mw8.0 to 8.3 give the smallest deviation from data, suggesting the saturation of ground motion intensity at large magnitudes. When the shortest distance from the strong motion generation areas is used, however, the scattering of data becomes smaller and the curve for Mw9.0 fits acceleration data. Results thus change with the definition of distance. This suggests that a consideration of the rupture heterogeneity is important in strong motion prediction for gigantic earthquakes.

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