10-10-2012, 05:20 PM
Traditional Earthquake Safe Housing Practices of North East India
Abstract
North Eastern parts of India are highly prone to earthquakes. The entire region falls under Zone
V (corresponding to MMI IX or more) as per the seismic hazard map of the country (IS1893-
2002). The seismic activity of the region is attributed to the subduction zone created due to the
collision of Indian and Eurasian plate boundaries. This region had been hit by two great
earthquakes in 1897 (Shillong M 8.6) and 1950 (Assam, M8.7). The region keeps on facing
earthquakes of lesser magnitude on regular basis.
Realizing the high hazard potential and vulnerability of the region local people have developed
construction practices to face earthquakes safely. The region has two famous earthquake safe
construction practices, which have been emerged over a period of time and have proven their
resilience against earthquakes. Housing construction practices followed in the region had played
a significant role in reducing the impact of regularly occurring earthquakes. These techniques are
‘Assam Type House’ and ‘Thatch House’. These housing typologies are common throughout the
Northeast India. Majority of such houses are used for residential purposes. Typically these
houses are built with light weight locally available material like bamboos, wooden planks, thatch
etc. Such houses have a proper system of bamboo/wooden beam-column and fulfill the
earthquake safety requirements of rectangularity and simplicity. These housing types have
demonstrated some of the basic principles of earthquake safe construction of non-engineered
buildings like appropriate sitting and location on firm soils, good building configuration i.e. its
form and shape in plan and elevation; location and size of major structural elements; number,
location and size of openings; and connection details of non-structural elements with main
structural system. Due to proper connection between different elements, such houses have a
proper integral action due to which they act as a single unit. The paper will examine these
techniques and propose few modifications to improve the earthquake resistance of these
buildings.