Traditional Seismic Resistance Houses in the Sikkim Himalaya-Need for Extensive Exploration and Documentation

RADHIKABHATTARAI

Sikkim, state of India covers the area of 7,096 sq.km. It lies in high seismically active zone (IV) due to movement of two active convergent plate namely the Indian plate and the Eurasian Plate. As a result, Sikkim hasfaced 89 earthquakes both minor and major within 60 years according to Bhukosh, GSI data (1959-2019).Mostly Sikkim remembers two major earthquake. 14^th February 2006 earthquake with magnitude 5.3 (USGS) and 18^th September 2011 Earthquake with magnitude 6.9. This two earthquake caused numerous fatalities and several damages in Sikkim’s infrastructures like, houses, roads, schools, hospital etc. Surprisingly in both the Earthquake cases traditional houses/ architecture which was built with local available materials like stone, mud, timber, and bamboo performed well as compare to modern concrete buildings (RCC).

According to (Kaushik et al., 2006) Ekra House performed well in Nandok East Sikkim in comparison to other modern building like Raj Bhawan during 2006 Earthquake. According to Khawas&Rai (2017) around 40,000 houses was damaged in 18^th September 2011 earthquake, however only 4 percent damaged houses belonged to Traditional Houses in total.Taking this as a good example, identifying and documenting the seismic resistance traditional houses in Sikkim Himalaya is vital.Documentation can help us to identify those housing structure which have stood stand still even during numerous earthquake hazards. After identification, a scientific exploration can be done to understand its architectural components. Who knows the much needed ingredient or knowledge for building modern seismic resistance structure are hidden inside the traditional architecture.

To verify the above secondary data, the brief survey was conducted during my research within the Sikkim Himalayan Area. Certain criteria like materials used, age of house, climatic adaptation, cost effectiveness and number of earthquake it withstand was specially taken into account. More than 12 houses was identified, however, I would like to mention four traditional houses here.

1.      PanditGhar (Nepali House) situated in sub-tropical climatic zone of Sikkim Himalaya. It was built with the use of materials like stone, mud, timber (Lapsi tree) also known as “Choerospondiasaxillaris” and with tin roof. The house is built in the year 1906 (approx. 120 years ago). Thus, the house clearly resisted more then 89 earthquakes.Only minor cracks can be found till today and it still stands tall. This house shows the flexibility, climatic adaptability and smart design of building in seismically active zone of Sikkim Himalaya. 

2.      ??DhokaGhar (52 Doors House) is located in sub-tropicalclimatic zone of Sikkim Himalaya. This house was built in the year 1897 (approx. 130 years ago). It was built with the available local materials like stone, mud, timber and with steel roof. The house was constructed using various local timbers, each valued for its strength and suitability. These included Chap (Castanopsisindica), Shakwa (AlnusNepalensis), Kimbu(Morus Alba), Chilawune(SchimaWallichii), Panisaj (TerminaliaMyriocarpa), Lampate(MicheliaChampaca), and Tuni (ToonaCiliata), all native to the Eastern Himalaya. This house have also survived more than 89 earthquakes.However, due to 2011 earthquake the house is in poor condition and shows signs of damage. The walls on the lower floor have cracks, the plaster is falling off and some parts of the house look weak. But this kind of damage is common in old houses if there is lack of proper maintenance.

3.      Lepcha house, also known as Pentongare mostly found in tropical, temperate and sub-alpine climate zone of Sikkim Himalaya. This house was built in the year 1947 (approx. 78 years ago) with the use of locally available materials. This house have also survived from more than 89 earthquakes and it still stand today. The uniqueness of this house is that not a single needle or metal string was used during its construction. Nine wooden logs have been used as a pillar in such a way that it defies the concept of gravity.

4.      Ekra house are generally found in almost every climatic zone of Sikkim Himalaya.However, this traditional Ekra house was built in the year 1957 (approx. 65-70 years ago) using locally available natural materials. Local carpenters constructed it with their inherited skills, using Malibas (Bambusa nutans), a flexible bamboo also known as Hamilton’s bamboo, Tuni kath (scientific name: Toona ciliata), commonly referred to as Indian mahogany or red cedar, and locally gathered stone. The house is normally 30 feet long and 18 feet wide. Over the decades, this house have experienced more than 89 earthquakes. It still remains strong, although it requires maintenance, such as minor repairs, every three to four years.

Thus, after experiencing the evidences, what we can say is that, this traditional houses needs a systematic and scientific documentation. This traditional houses have the nature of durability, flexibility and the characteristics of eco-friendliness and cost effectiveness. It is easy to repair and it is well designed for earthquake hazards in this part of the world. Traditional architecture and traditional knowledge have evolve from centuries of experience and adaptation with the surrounding environment. Thus, it holds the ingredient of linkage or connection between human and environment in a sustainable way. Today Sikkim needs a comprehensive earthquake preparedness and mitigation measure. Comprehensive means a holistic framework for Disaster Risk Reduction.This traditional knowledge system of our elders and ancestors can help to fill the important disaster planning gap in our formal disaster management plan. If we be able to mix this traditional wisdom with our modern methods, we could build safer and stronger home for our coming generation. May be the best idea for the future lies hidden within the past knowledge.

(The author is a MA Geography student of Sikkim Alpine University, Namchi. She is currently doing her MA Dissertation underthe guidance of Dr. PribatRai, Assist Professor, Geography, SAU. Her Dissertation title is “Identifying the Seismic Resistance Traditional Houses in the Sikkim Himalaya”)