Junji Kiyono
Department of Urban Management, Graduate School of Engineering, Kyoto University

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GROUND MOTION IN YOGYAKARTA CITY, YOGYAKARTA SPECIAL PROVINCE, INDONESIA ON DENSELY MICROTREMOR OBSERVATIONS AND SHEAR WAVE VELOCITY Zaw Lin Kyaw; Subagyo Pramumijoyo; Salahuddin Husein; Teuku Faisal Fathani; Junji Kiyono
Journal of Applied Geology Vol 5, No 1 (2013)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1035.371 KB) | DOI: 10.22146/jag.7203

Abstract

Microtremor is currently considered the foremost tool in site effect studies. The ground motion is estimated with microtremor observations, meaning that subsoil mechanical properties and geometry are evaluated and from them an estimate of local amplification is computed. Here, the ground motion is studied by the site effects of seismic hazard zonation of urban areas in Yogyakarta City. The main purpose of this paper is zoning the geological engineering features and assessing seismic of the research urban area. In this regard, the microtremors are measured at 274 sites by single station sampling method and Nakamura technique. The microtremors of all over the city are processed by a model of Mitutoyo-GPL-6A3P. The amplification factor generally ranges between 0.70 and 5.56 and the natural frequency normally varies between 0.40 and 3.30 Hz. The information layers are prepared in GMT used for detecting the zonation of potential seismic hazard. The shear wave velocity is calculated in 12 existing drilling sites based on the geotechnical approach of SPT for soil condition. To study the ground motion, geological engineering condition is investigated using amplification factor, natural frequency, shear wave velocity maps which are analyzed using densely single microtremor observation and SPT from existing drilling sites. Keywords: Ground motion, amplification factors, natural frequency; H/V spectral ratio, microtremor observations, Yogyakarta Urban
Estimation of Strong Ground Motion at Mandalay Region, Myanmar pyi soe thein; Khaing Khaing; Kyi Kyi Lin; Subagyo Pramumijoyo; Junji Kiyono
Journal of Applied Geology Vol 10, No 1 (2025)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jag.105847

Abstract

Mandalay region lies very closed to the dextral Sagaing fault. In the historical record, several earthquakes happened in and around Mandalay region from the beginning of the year of 1400. Among them the most distinct event is the Sagaing earthquake struck on July 16, 1956. This research mainly focuses on results of microtremor survey at 143 sites and 25 data from the boreholes for determination of sediment thickness characteristics and strong ground motion analysis in Mandalay region. For the accurate prediction of earthquake ground motions, the investigation of three elements in its process, namely the source, path, and site effects, is crucial, and their accuracy and reliability should be evaluated. The subsurface profiles, predominant periods, shear wave velocity structures and information about sediment thickness or depth of engineering bed rock were evaluated based on data from boreholes, microtremor survey and laboratory results, combining with inversion program. The shear wave velocity of the top layer is Vs ≤ 190 m/s. The spectral amplitudes of the estimated strong ground motions were smaller at around 0.5 Hz and larger at around 3 Hz in Mandalay region. The peak ground acceleration becomes more than 0.8 g in some areas, which causes severe damage for buildings in high probability.