A series of surveys are being implemented through this project for an earthquake risk assessment in Bhutan, i.e., if an earthquake occurs, what shape of the land surface is damaged and to what extent, what kind of underground material makes the ground shaking larger and what type of traditional building is fragile? The assessment survey is conducted by two teams: the team for earthquakes analyses the real seismic data in Bhutan, studies the shape and features of land surfaces in detail, finds the location of active faults and measures the extent of ground-motion amplification caused by shaking. The other, or the building team, categorizes traditional buildings on the basis of features such as their structure, number of stories and age, and measures microtremors to understand the characteristics of different buildings. Both teams use two pilot sites, where Bhutanese project members learn the steps of the surveys and how to develop earthquake hazard maps. Since July 2019, the building team has studied rammed earth houses in Essuna village in western Bhutan, Paro District, where the team observed the location of the houses, their types, shaking characteristics and so on.
The building team observing a rammed earth house in Essuna village
A sensor measuring the microtremor on a rammed earth house
Three full-scale mock houses were built in the examination facility in the premises of the Department of Culture (DOC). The houses were reinforced during their construction; one is a rammed earth house reinforced with structures such as a horizontal band of reinforced concrete and vertical iron bars, the second is a stone masonry house bound with cement mortar with similar reinforcement and the third is a stone masonry (cement mortar) house without any reinforcement. In October 2019, the mock houses will be pushed with a hydraulic jack system to test the effectiveness of the reinforcements.
Left: Stone masonry house without reinforcement, middle: rammed earth house with reinforcement, right: stone masonry house with reinforcement