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Your search keyword '"Yamanaka, Hiroaki"' showing total 9 results
Start Over Author "Yamanaka, Hiroaki" Topic site amplification
9 results on '"Yamanaka, Hiroaki"'

8. Exploration of deep sedimentary layers in Tacna city, southern Peru, using microtremors and earthquake data for estimation of local amplification

Author

Aguilar Bardales, Zenón, Lázares La Rosa, Fernándo, Calderon, Diana, Saguchi, Kouichiro, Chimoto, Kosuke, Quispe Gamero, Mileyvi Selene, Yamanaka, Hiroaki, and yamanaka@depe.titech.ac.jp

Subjects
Microtremors, 0211 other engineering and technologies, S-wave profile, 02 engineering and technology, Receiver function, 010502 geochemistry & geophysics, 01 natural sciences, symbols.namesake, Geochemistry and Petrology, Rayleigh wave phase velocity, Rayleigh wave, Site amplification, 0105 earth and related environmental sciences, 021110 strategic, defence & security studies, Hydrogeology, 2001 southern Peru earthquake, Geophysics, Basement (geology), symbols, Sedimentary rock, Microtremor, Phase velocity, Structural geology, Seismology, Geology
Abstract

S-wave velocity profiles of sedimentary layers in Tacna, southern Peru, based on analysis of microtremor array data and earthquake records, have been determined for estimation of site amplification. We investigated vertical component of microtremors in temporary arrays at two sites in the city for Rayleigh wave phase velocity. A receiver function was also estimated from existing earthquake data at a strong motion station near one of the microtremor exploration sites. The phase velocity and the receiver function were jointly inverted to S-wave velocity profiles. The depths to the basement with an S-wave velocity of 2.8 km/s at the two sites are similar as about 1 km. The top soil at the site in a severely damaged area in the city had a lower S-wave velocity than that in a slightly damaged area during the 2001 southern Peru earthquake. We subsequently estimate site amplifications from the velocity profiles and find that amplification is large at periods from 0.2 to 0.8 s at the damaged area indicating possible reasons for the differences in the damage observed during the 2001 southern Peru earthquake.

Published
2015

9. Cause of destructive strong ground motion within 1–2 s in Mukawa town during the 2018 Mw 6.6 Hokkaido eastern Iburi earthquake.

Author

Takai, Nobuo, Shigefuji, Michiko, Horita, Jun, Nomoto, Shingo, Maeda, Takahiro, Ichiyanagi, Masayoshi, Takahashi, Hiroaki, Yamanaka, Hiroaki, Chimoto, Kosuke, Tsuno, Seiji, Korenaga, Masahiro, and Yamada, Nobuyuki

Subjects
MOTION, PHASE velocity, UNDERGROUND construction, EARTHQUAKES, CITIES & towns
Abstract

We investigated the cause of destructive ground motion during the 2018 Hokkaido eastern Iburi earthquake. We conducted strong motion observations of aftershocks and microtremors and the surface wave method in the damaged areas of the town of Mukawa, Hokkaido prefecture, Japan. The ground accelerations were continuously recorded during a period of approximately 3 months after the main shock on September 6, 2018. The heavily damaged buildings were mainly situated around the strong motion station (HKD126) in Mukawa town. Such concentration of damage can be explained by the strong power that was observed in the 1–2 s period of the response spectrum at this station. We estimated the S-wave velocity profiles of this station site and a temporary station site that was installed on a nearby hill. The estimated S-wave velocity, which was inverted from phase velocity structures with the microtremor array and the surface wave method observations explained the difference in the SH-wave amplification characteristics between the two sites. An analysis of HKD126 and the temporarily observed records clearly indicates the strong effects of the local geological conditions on the heavily damaged area of Mukawa. The strong ground motion power generated during the main shock in Mukawa for 1–2 s period was mainly amplified by this shallow underground velocity structure. [ABSTRACT FROM AUTHOR]

Published
2019
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