Vol.:(0123456789) 1 3 Innovative Infrastructure Solutions (2022) 7:361 https://doi.org/10.1007/s41062-022-00958-x TECHNICAL PAPER Deterministic seismic hazard analysis for Phuentsholing region of southern Bhutan considering local site efects Soumyadeep Sengupta 1  · Raju Sarkar 2  · Sreevalsa Kolathayar 3  · Dowchu Drukpa 4 Received: 18 July 2021 / Accepted: 4 October 2022 © Springer Nature Switzerland AG 2022 Abstract Phuentsholing is a thriving border town in the southwestern part of Bhutan. With the development of infrastructure over time, the safety of the residence and lifeline buildings becomes a matter of concern. Bhutan lies in the Himalayan mountain ranges, which is considered one of the most active regions for seismic events. The Indian seismic code, IS 1893-2016, has assigned Zone IV for the region, which signifes the large risk that exists for all the structures. Therefore, conducting a seismic hazard assessment for the site becomes extremely necessary before any major construction. The present study focusses to perform the deterministic seismic hazard analysis (DSHA) around certain points of interest in the town of Phuentsholing, in Bhutan. Furthermore, site-specifc response spectra for Pipaldhara-1, Pipaldhara-2, Kabreytar-1, Kabreytar-2 and Phuentsholing town were plotted from the results of the DSHA. It is estimated that a peak ground acceleration ranging from 0.11 to 0.14 g can be anticipated at the level of bedrock in the study region. Response spectra were plotted for the ground level using appropriate soil-amplifcation coefcients, derived from the analyses in the DEEPSOIL program. Keywords Seismic hazard assessment · Deterministic seismic hazard analysis (DSHA) · Seismic microzonation · Site- specifc response spectrum · Bhutan Introduction Estimation of seismic hazard for a particular region is impor- tant to plan developmental activities and construction in the region. Seismic hazard analysis may be determined either by a deterministic approach, where a certain earthquake scenario is presumed and is termed as deterministic seis- mic hazard analysis (DSHA) or by a probabilistic approach where uncertainties, in the earthquake magnitude, location and time of occurrence are considered, which is termed as probabilistic seismic hazard analysis (PSHA) [26]. Several researchers questioned the reliability of PSHA and recom- mended DSHA [7, 21, 25, 27, 55]. DSHA provides more reliable near feld constraints, and it is recommended over PSHA at highly vulnerable regions [19]. DSHA demands the quantitative estimation of the ground shaking hazard for an area and the process is convenient where tectonic fea- tures are practically dynamic and sound [49]. To assess the seismic hazard of a region, one must identify the sources of seismic activity of that area along with potential sources generating future strong ground motions. Broadly speaking, DSHA comprises four steps: (a) identifying all the possible sources of ground motion around the study site, (b) determi- nation of the nearest source to site distance which involves engineering judgement, (c) selection of suitable ground motion prediction equations (GMPEs) to evaluate ground motion characteristics of the site and (d) outline the peak ground acceleration of the site. * Raju Sarkar rajusarkar@dce.ac.in Soumyadeep Sengupta soumyadeepsengupta1997@gmail.com Sreevalsa Kolathayar sreevalsa@nitk.edu.in Dowchu Drukpa dawchu@gmail.com 1 School of Civil Engineering, Vellore Institute of Technology, Vellore, Tamil Nadu, India 2 Department of Civil Engineering, Delhi Technological University, Bawana Road, New Delhi, Delhi, India 3 Department of Civil Engineering, National Institute of Technology Karnataka, Mangaluru, India 4 Department of Geology and Mines, Ministry of Economic Afairs, Thimphu, Bhutan