JICA–Bhutan Seismic Risk Evaluation Project

The JICA–Bhutan Seismic Risk Evaluation Project, formally titled the "Project for Evaluation and Mitigation of Seismic Risk for Composite Masonry Buildings in Bhutan," is a bilateral scientific collaboration between Japan and Bhutan conducted under the Science and Technology Research Partnership for Sustainable Development (SATREPS) programme. Administered by the Japan International Cooperation Agency (JICA) and the Japan Science and Technology Agency (JST), the project aimed to evaluate seismic hazards in Bhutan and develop earthquake-resistant construction techniques for the kingdom's predominant building typologies — rammed earth, stone masonry in mud mortar, and adobe structures.^[1]

Bhutan lies within a seismically active zone along the Himalayan arc, where the Indian tectonic plate subducts beneath the Eurasian plate. Most residential and public buildings in the country are constructed from rammed earth or stone masonry without modern reinforcement, making them acutely vulnerable to ground shaking. The devastating 2009 Bhutan earthquake, a magnitude 6.1 event centred in Monggar District, killed at least eleven people, injured dozens more, and damaged or destroyed over 5,167 buildings, starkly demonstrating this vulnerability.^[2]

Project Scope and Methodology

The SATREPS project was implemented in partnership with Bhutan's Department of Culture and the Department of Disaster Management under the Ministry of Home and Cultural Affairs. Japanese researchers from multiple universities collaborated with Bhutanese engineers and officials to conduct comprehensive seismic hazard mapping, building vulnerability surveys, and structural testing of traditional construction methods.^[3]

A central component of the project was the establishment of a seismic testing facility equipped with a shaking table capable of simulating earthquake forces on small-scale house models and full-scale rammed earth wall sections. These vibration tests enabled researchers to observe the failure modes of traditional Bhutanese structures under controlled seismic loading and to evaluate the effectiveness of proposed retrofitting techniques.^[4]

Field surveys documented the construction typologies of traditional houses across multiple dzongkhags, categorising them by wall material (rammed earth, stone, adobe), number of storeys, and structural condition. The data fed into probabilistic seismic risk models that estimated casualties and economic losses under various earthquake scenarios.

Worst-Case Scenario Findings

The project's risk assessment produced alarming projections. A worst-case scenario — a major earthquake striking at night when most inhabitants are indoors and asleep — could cause approximately 9,000 fatalities, 10,000 serious injuries, and displace more than 40,000 people. These figures reflected the acute vulnerability of unreinforced masonry structures, which tend to collapse catastrophically under strong lateral forces, and the limited emergency response capacity in Bhutan's rugged terrain.^[5]

The 2009 earthquake provided a grim empirical baseline. The Post-Disaster Needs Assessment (PDNA) conducted jointly by the Royal Government of Bhutan and the World Bank estimated total damage and losses at BTN 2,501 million (approximately USD 54 million), concentrated in the eastern dzongkhags of Monggar, Trashigang, and Samdrup Jongkhar. Many casualties resulted from the collapse of traditional rammed earth houses onto sleeping occupants.^[6]

Outcomes and Recommendations

Based on its findings, the project developed general guidelines for improved earthquake-resistant construction techniques applicable to rammed earth structures. These guidelines include recommendations for reinforced corner connections, horizontal tie beams at floor and roof levels, and reduced wall heights — interventions designed to be affordable and compatible with traditional building aesthetics, which are protected under Bhutan's architectural heritage regulations.^[7]

The project also produced a manual for disaster mitigation education and conducted training seminars for engineers, construction workers, and community members across multiple districts. The emphasis on community-level engagement reflected the recognition that in rural Bhutan, where most construction is undertaken by households rather than professional builders, earthquake preparedness must be integrated into local knowledge systems.^[8]

Significance

The JICA SATREPS project represents one of the most comprehensive seismic risk studies ever undertaken in Bhutan. Its findings have informed national disaster preparedness planning and contributed to ongoing policy discussions about balancing the preservation of Bhutan's distinctive rammed earth building traditions with the imperative of protecting human life in one of the world's most seismically active regions.

References

1. "Project for Evaluation and Mitigation of Seismic Risk for Composite Masonry Buildings in Bhutan." SATREPS / JST.
2. "2009 Bhutan earthquake." Wikipedia.
3. "Monthly Report for June 2021." JICA Technical Cooperation Projects.
4. "Monthly Report for July 2018." JICA Technical Cooperation Projects.
5. "Is Bhutan prepared for an earthquake?" Kuensel Online.
6. "Recovery, Reconstruction and Risk Reduction: Bhutan PDNA 2011." GFDRR / World Bank.
7. "Monthly Report for May 2022." JICA Technical Cooperation Projects.
8. "How can Bhutan better prepare for earthquakes?" World Bank Blogs.