Acquisition of Ground Information in Downtown Yangon for Bosai Operation Support System
Tun Naing*1,, Su Thinzar*2, Muneyoshi Numada*3, Khin Than Yu*4, and Kimiro Meguro*2
*1Department of Engineering Geology, Yangon Technological University
Gyoegone, Insein, Yangon 11011, Myanmar
*2Department of Petroleum Engineering (Engineering Geology Section), Technological University (Mandalay), Mandalay, Myanmar
*3Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
*4Department of Civil Engineering, Yangon Technological University, Yangon, Myanmar
Yangon is one of the most populated and socio-economically important cities in Myanmar. Unfortunately, it is located in a moderately active-seismic area, and significant damage and loss will be incurred if an earthquake occurs there in the future. The seismogenic Sagaing Fault passes 40 km to the E of Yangon, which has experienced several destructive earthquakes in the past. The urban area studied here, Kyauktada, Pazundaung, and Botahtaung townships, are located mostly on a soft alluvial plain, which is mainly composed of sand, silt, and clay, which are sediments prone to amplify seismic waves. The Yangon Bosai Operation Support System (BOSS), designed to establish a proper disaster management system based on the potential damage that a future earthquake might cause, is under development. BOSS has two components damage prediction and damage response – which are based on predicted damage and current response capability and practices in Myanmar. For damage prediction, major inputs include information on the underlying soils, building construction and associated fragility functions, based on different building types. Microtremor survey is a useful tool for reviewing underlying soil layer information, as this can significantly affect vulnerability assessments and the identification of potential damages. Microtremor surveys and analyses were therefore conducted at 88 sites throughout the studied urban areas to acquire key ground information for BOSS. Our analyses showed that the fundamental frequency of horizontal to vertical spectral ratio (H/V ratio) of microtremors generally ranged 0.6–2.4 Hz, while the peak amplitude was between 1.3 and 4.0. Soil thickness ranged 60–210 m, and the average shear wave velocity over the ground’s upper 30 m, Vs30, was in the range 180–560 ms-1. All outcomes from this research will become key input parameters for BOSS development in Yangon.
-  Y. Nakamura, “On the H/V Spectrum,” Proc. of the 14th World Conf. on Earthquake Engineering (14WCEE), 2008.
-  H. Arai and K. Tokimatsu, “S-Wave Velocity Profiling by Joint Inversion of Microtremor Dispersion Curve and Horizontal to Vertical (H/V) Spectrum,” Bulletin of the Seismological Society of America, Vol.95, No.5, pp. 1766-1778, 2005.
-  Department of Population, Ministry of Immigration and Population, “The Union Report –The 2014 Myanmar Population and Housing Census–,” Census Report Volume 2, 2015.
-  “Google Earth Image,” 2018, http://www.google.com/ [accessed February 25, 2020]
-  W. Naing, “The Comprehensive Analysis of Surface and Subsurface Geology of Yangon Area,” M.Sc. thesis, Yangon University, 1972.
-  “Advanced National Seismic System, ANSS catalog,” 1900-2018, quake.geo.berkeley.edu/anss/ [accessed January 15, 2018]
-  T. Naing, H. Kawase, S. Matsushima, M. Thant, C. T. Mon, T. H. Tin, and K. K. K. Oo, “S-Wave Velocity Profiles Based on the HVRs in Bago, Myanmar for Seismic Hazard Mapping,” Proc. of the 2nd Int. Symp. on Earthquake Engineering (JAEE), 2013.
-  H. Kawase, F. J. Sánchez-Sesma, and S. Matusushima, “Application of the H/V Spectral Ratios for Earthquake and Microtremor Ground Motions,” The 4th Int. IASPEI/IAEE Symp.: Effect of Surface Geology on Seismic Motion, 2011.
-  F. J. Sánchez-Sesma, M. Rodríguez, U. Iturrarán-Viveros, A. Rodríguez-Castellanos, M. Suarez, M. A. Santoyo, A. García-Jerez, and F. Luzón, “Site effects assessment using seismic noise,” Proc. of the 9th Int. Workshop on Seismic Microzoning and Risk Reduction (IWSMRR), 2010.
-  H. Arai and K. Tokimatsu, “S-wave velocity profiling by inversion of microtremor H/V spectrum,” Bulletin of the Seismological Society of America, Vol.94, No.1, pp. 53-63, 2004.
-  F. J. Sánchez-Sesma, R. L. Weaver, H. Kawase, S. Matsushima, F. Luzón, and M. Campillo, “Energy partitions among elastic waves for dynamic surface loads in a semi-infinite solid,” Bulletin of the Seismological Society of America, Vol.101, No.4, pp. 1704-1709, 2011.
-  Y. Hirokawa, S. Matsushima, H. Kawase, T. Naing, and M. Thant, “Estimation of underground structures in Yangon City, Myanmar using single-station and array microtremors,” J. of Japan Association for Earthquake Engineering, Vol.16, No.1, pp. 1_49-1_58, 2016.
-  T. Imai, “P- and S-wave velocities of the ground in Japan,” Proc. of the 9th Int. Conf. on Soil Mechanics and Foundation Engineering, pp. 257-260, 1977.
-  T. Imai, “P- and S-wave velocities of the ground in Japan,” Proc. of 9th ISCMFE, Vol.2, pp. 257-260, 1981.
-  T. Imai, H. Fumoto, and K. Yokota, “The relation of mechanical properties of soil to P- and S-wave velocities in Japan,” Proc. of 4th Japan Earthquake Engineering Symp., pp. 89-96, 1975 (in Japanese).