Ikuo Cho
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View article: Construction of average <i>S</i>-wave velocity maps using simplified microtremor method: case study of area with pyroclastic flow deposits to the east of Aso caldera, Japan
Construction of average <i>S</i>-wave velocity maps using simplified microtremor method: case study of area with pyroclastic flow deposits to the east of Aso caldera, Japan Open
SUMMARY In this study, we compare the usability of a simplified microtremor-based empirical method and a conventional microtremor method based on an inversion analysis of a subsurface velocity structure model for constructing a map of aver…
View article: Comparison of the Frailty Phenotype and the Korean Version of the FRAIL Scale
Comparison of the Frailty Phenotype and the Korean Version of the FRAIL Scale Open
Background: Frailty is an important factor in the quality of life, because physical functions decrease with increasing frailty and cannot return to their previous state. This can lead to falls, hospitalization, dependency, and early mortal…
View article: Development of predominant-period and average S-wave velocity maps for Hue City, Central Vietnam
Development of predominant-period and average S-wave velocity maps for Hue City, Central Vietnam Open
We have developed maps of the predominant period of the ground and average S-wave velocity to depths of 10, 20 and 30 m (VS10, 20 and 30) as the fundamental data for seismic hazard assessment for Hue City, Central Vietnam. We conducted mic…
View article: Evolution, speed, and precession of the parsec-scale jet in the 3C 84 radio galaxy
Evolution, speed, and precession of the parsec-scale jet in the 3C 84 radio galaxy Open
We present high-resolution images of the radio source 3C 84 at 43 GHz from 121 observations conducted by the BEAM-ME monitoring program between 2010 and 2023. Imaging was performed using the recent forward modeling imaging method eht-imagi…
View article: Evolution, speed, and precession of the parsec-scale jet in the 3C 84 radio galaxy
Evolution, speed, and precession of the parsec-scale jet in the 3C 84 radio galaxy Open
We present high resolution images of the radio source 3C 84 at 43 GHz, from 121 observations conducted by the BEAM-ME monitoring program between 2010 and 2023. Imaging was performed using the recent forward modeling imaging method eht-imag…
View article: Shallow Microtremor Array Survey Using Miniature and Small Arrays: Strategy for Efficient and Feasible Dense Survey
Shallow Microtremor Array Survey Using Miniature and Small Arrays: Strategy for Efficient and Feasible Dense Survey Open
We investigated the applicability of miniature microtremor arrays with a radius of a few meters or less to shallow surveys (up to a few tens of meters). It is shown that the upper limit wavelength normalized by the seismometer separation d…
View article: S-wave velocity structures and ground motion characteristics beneath valley bottom lowlands: A case study from the lowlands along the Kanda and Furukawa rivers incising the Musashino Upland, Tokyo, central Japan
S-wave velocity structures and ground motion characteristics beneath valley bottom lowlands: A case study from the lowlands along the Kanda and Furukawa rivers incising the Musashino Upland, Tokyo, central Japan Open
東京都区部の武蔵野台地を刻む神田川(善福寺川)および古川(渋谷川)沿いにおいて常時微動観測を実施した.下流部の谷底低地では軟弱な沖積層が厚く,平均S波速度は低い値を示した.H/V スペクトルのピークが低周波数帯域(1.5~1.6 Hz 付近)にみられた地域は,1923年関東地震で被害が著しかった地域にほぼ一致した.一方で中・上流部では,谷底低地よりも,むしろその周辺の関東ローム層や東京層の軟らかい泥層が分布する台地のほうが軟らかい地盤特性を示した.つまり下流部と中・上流部で…
View article: Broadband Multi-wavelength Properties of M87 during the 2018 EHT Campaign including a Very High Energy Flaring Episode
Broadband Multi-wavelength Properties of M87 during the 2018 EHT Campaign including a Very High Energy Flaring Episode Open
The nearby elliptical galaxy M87 contains one of the only two supermassive black holes whose emission surrounding the event horizon has been imaged by the Event Horizon Telescope (EHT). In 2018, more than two dozen multi-wavelength (MWL) f…
View article: Interpretable and Flexible Generalization of Evolving Computational Materials' Framework for Heterogeneous Composite Structures
Interpretable and Flexible Generalization of Evolving Computational Materials' Framework for Heterogeneous Composite Structures Open
Recently, computational material models accelerated innovations by harnessing machine learning (ML) methods, but they face challenges.It is difficult to incorporate internal heterogeneity and diverse boundary conditions (BC's) into existin…
View article: Outlining microtremor array survey: With a view to application to shallow geological surveys
Outlining microtremor array survey: With a view to application to shallow geological surveys Open
A microtremor array survey is a tool for modeling subsurface S-wave velocity structure using small ground oscillations, or microtremors, which can be recorded by multiple seismometers at the surface. This paper presents an overview of the …
View article: Ground motion characteristics along a transverse section (Ueno-Koiwa Line) of the buried valley beneath the Tokyo Lowland, central Japan
Ground motion characteristics along a transverse section (Ueno-Koiwa Line) of the buried valley beneath the Tokyo Lowland, central Japan Open
To better understand how ground motion in the Tokyo Lowland is affected by the geological conditions in the shallow subsurface, we analyzed borehole logs and conducted microtremor observations along the Ueno-Koiwa survey line, which crosse…
View article: Archive of the microtremor data observed at rock/stiff-soil sites and the analysis results
Archive of the microtremor data observed at rock/stiff-soil sites and the analysis results Open
This archive includes the microtremor data observed at 15 rock/stiff-soil sites and the analysis results, which were fully described in a paper "Spatial autocorrelation method for a simple microtremor array survey at rock/stiff-soil sites"…
View article: Archive of the microtremor data observed at rock/stiff-soil sites and the analysis results
Archive of the microtremor data observed at rock/stiff-soil sites and the analysis results Open
This archive includes the microtremor data observed at 15 rock/stiff-soil sites and the analysis results, which were fully described in a paper "Spatial autocorrelation method for a simple microtremor array survey at rock/stiff-soil sites"…
View article: Array-size dependency of the upper limit wavelength normalized by array radius for the standard spatial autocorrelation method
Array-size dependency of the upper limit wavelength normalized by array radius for the standard spatial autocorrelation method Open
View article: Archive of the analysis results of the microtremor data obtained from a seismic array with a radius of 0.58 m distributed to the participants of the blind prediction experiments for the ESG6 symposium
Archive of the analysis results of the microtremor data obtained from a seismic array with a radius of 0.58 m distributed to the participants of the blind prediction experiments for the ESG6 symposium Open
This is a supplemental material of the paper "Array-size dependency of the upper limit wavelength normalized by array radius for the standard spatial autocorrelation method" by Ikuo Cho, published in Earth, Planets and Space. It consists o…
View article: Archive of the analysis results of the microtremor data obtained from a seismic array with a radius of 0.58 m distributed to the participants of the blind prediction experiments for the ESG6 symposium
Archive of the analysis results of the microtremor data obtained from a seismic array with a radius of 0.58 m distributed to the participants of the blind prediction experiments for the ESG6 symposium Open
This is a supplemental material of the paper "Array-size dependency of the upper limit wavelength normalized by array radius for the standard spatial autocorrelation method" by Ikuo Cho, published in Earth, Planets and Space. It consists o…
View article: Ground motion characteristics and the depth of the S-wave velocity discontinuity in the post-LGM incised-valley fills beneath the Tokyo Bay area, central Japan, based on microtremor surveys
Ground motion characteristics and the depth of the S-wave velocity discontinuity in the post-LGM incised-valley fills beneath the Tokyo Bay area, central Japan, based on microtremor surveys Open
東京都湾岸部の沖積低地（東京低地）の16地点で常時微動観測を行い，各地点で地盤の平均S波速度とH/Vスペクトルのピーク周波数すなわち地盤の共振周波数を推定した．これにより，表層の軟弱層が厚いと共振周波数が低くなることが示された．1/4波長則を適用して地盤の共振周波数を特徴付けるS波速度不連続面の深さを算出したところ，ばらつきは大きいものの，検討した13地点中7地点において，従来物性境界と考えられてきた七号地層/有楽町層境界よりも下位の，七号地層の砂泥互層中に位置することが示…
View article: An assessment of uncertainties in VS profiles obtained from microtremor observations in the phased 2018 COSMOS blind trials
An assessment of uncertainties in VS profiles obtained from microtremor observations in the phased 2018 COSMOS blind trials Open
View article: Synthetic data used in Cho et al. (2021)
Synthetic data used in Cho et al. (2021) Open
Archive of the synthetic data used to verify equations formulated in Cho et al. (2021). Cho, I., Yoshida, K., & Uebayashi, H., 2021, Microtremor surveys base on rotational seismology: theoretical analysis with focus on separation of Raylei…
View article: Synthetic data used in Cho et al. (2021)
Synthetic data used in Cho et al. (2021) Open
Archive of the synthetic data used to verify equations formulated in Cho et al. (2021). Cho, I., Yoshida, K., & Uebayashi, H., 2021, Microtremor surveys base on rotational seismology: theoretical analysis with focus on separation of Raylei…
View article: Raw data and analysis results in paper by Cho and Iwata published in JGR
Raw data and analysis results in paper by Cho and Iwata published in JGR Open
Thirty-two microtremor arrays were analyzed in Cho and Iwata (2021) (Cho, I., & Iwata, T., 2021, Limits and benefits of the spatial autocorrelation microtremor array method due to the incoherent noise, with special reference to the analysi…
View article: S-wave velocity structures and ground motion characteristics of loam terraces: The case of the Utsunomiya area, Tochigi Prefecture, central Japan
S-wave velocity structures and ground motion characteristics of loam terraces: The case of the Utsunomiya area, Tochigi Prefecture, central Japan Open
一般に地盤が良いとされるローム台地において,ローム層が地盤震動特性に与える影響を知るために,栃木県宇都宮地域で段丘面ごとに微動アレイ観測を行った.その結果,調査地域の段丘を覆うローム層はS波速度が130~150m/sと低いこと,また古い段丘ほどローム層が厚いために深度30mまでの平均S波速度は低く,H/Vスペクトルのピーク周波数も低周波側にシフトすることが明らかになった.一方で,鬼怒川や五行川などの河床は主に礫質堆積物からなりローム層を欠くため,河川沿いの低地では平均S波速…
View article: Stratigraphy, distribution patterns, and ground motion characteristics of the Pleistocene Setagaya and Tokyo formations beneath the Musashino Upland, Setagaya, Tokyo, central Japan
Stratigraphy, distribution patterns, and ground motion characteristics of the Pleistocene Setagaya and Tokyo formations beneath the Musashino Upland, Setagaya, Tokyo, central Japan Open
東京都世田谷区の武蔵野台地の下に分布する更新統世田谷層及び東京層の層序と地盤震動特性について検討した.世田谷層はMIS 6に開析された谷地形をMIS 5e前期~中期に埋積した地層であり,内湾成の軟らかい泥層を主体とする.一方,この地域の東京層は,MIS 5e中期?~後期の湾奥で形成された砂層などからなり,世田谷層とは対照的に広範囲に比較的平坦に分布する.常時微動観測により,段丘礫層を伴わず世田谷層が厚く分布する地域では,1Hzにピークをもつ地盤震動特性が示された.首都圏の地…
View article: A Bayesian Approach to Microtremor Array Methods for Estimating Shallow <i>S</i> Wave Velocity Structures: Identifying Structural Singularities
A Bayesian Approach to Microtremor Array Methods for Estimating Shallow <i>S</i> Wave Velocity Structures: Identifying Structural Singularities Open
This paper proposes applying Bayesian inference to the problem of estimating shallow S wave velocity structures—in particular, those containing a structural singularity (a low‐velocity layer sandwiched between high‐velocity layers or a hig…
View article: Datasets Of Microtremor Arrays And Phase Velocities Of Rayleigh Waves
Datasets Of Microtremor Arrays And Phase Velocities Of Rayleigh Waves Open
Observed microtremor array data / Synthetic and observed phase-velocity data used in Cho and Iwata [2018, submitted to JGR].
View article: Datasets Of Microtremor Arrays And Phase Velocities Of Rayleigh Waves
Datasets Of Microtremor Arrays And Phase Velocities Of Rayleigh Waves Open
Observed microtremor array data / Synthetic and observed phase-velocity data used in Cho and Iwata [2018, submitted to JGR].
View article: Microtremor Array Data
Microtremor Array Data Open
Microtremor array data that are used for analyses with ESAC and nc-SPAC methods, which include both observed and numerically-synthesized waveforms.
View article: Microtremor Array Data
Microtremor Array Data Open
Microtremor array data that are used for analyses with ESAC and nc-SPAC methods, which include both observed and numerically-synthesized waveforms.
View article: Microtremor Data
Microtremor Data Open
Observed microtremor waveforms obtained with a linear seismic array.
View article: Simple assessment of shallow velocity structures with small-scale microtremor arrays: interval-averaged S-wave velocities
Simple assessment of shallow velocity structures with small-scale microtremor arrays: interval-averaged S-wave velocities Open
This article describes a method for processing microtremor records from a small-scale seismic array that allows interval-averaged S-wave velocities to be estimated for 10-m depth ranges down to a depth of 30 m. The method was applied to mi…