Quakes are not new to India, but casualties due to them are always more than those in developed countries like Japan and Switzerland which have adopted appropriate housing technologies in quake-prone regions to minimise the loss of life, says CBRI director Ram Iyengar.

Iyengar said CBRI has the know-how for designing quake-resistant houses and developing special building materials to withstand landslides and earthquakes.

Two teams of CBRI engineers have arrived in Chamoli to collect information on damage patterns, construction practices and building material use in the area, which will help work out a strategy on rehabilitation measures.

One team will concentrate its efforts in and around Chamoli town, which isthe epicentre, while the other will cover places away from the epicentre.

CBRI has recommended using the institute's precast concrete/stone blocks and clay bricks with 20 per cent flyash as substitute for the local soil which lacks clay and is not suitable for making bricks.

Flyash could be procured from the Bharat Heavy Electricals Limited (BHEL) thermal plant at Hardwar.

Traditional houses in Chamoli district are normally two-storeyed with a 2.4-metre-high ground floor for keeping animals and a three-metre-high first floor for living. They have a timbre framework with walls of flat stones without mortar, Iyengar said.

No measures are, however, taken against possible seismic shocks in the structures.

Iyengar said houses in the area are mostly built of riverbed stones. The popular practice is to make concrete blocks of these stones and use them for construction.

CBRI's confidence in designing quake-resistant buildings stems from its recent experience in repairing houses for quake victims ofUttarkashi, Latur and Jabalpur.

Survey of damage due to the quake in the Marathwada region has shown that thick masonry walls with irregular-shaped stones in mud mortar without proper bonding at corners, and heavy roofs are the major causes of building collapse.

Strength of walls in these houses is poor which can be increased by fixing wire mesh on both sides of the walls and plastering with a specific combination of cement/sand mortar.

Sloping roof could also be constructed using steel and galvanised iron sheets over which thatch could be laid for thermal insulation, according to CBRI.

Scientists have also to ascertain the type of connection between the roof and walls before undertaking roof repairs, Iyengar said.

The institute's building materials division can identify local resource materials in hilly regions to prepare components such as bricks, blocks and roof panels.

It has offered repair and retrofitting technologies for withstanding future quakes, based on affordable building material andcomponents developed from local resources.

The institute has already assisted local authorities in damage survey, repair, strengthening and retrofitting of houses, school buildings and office complexes after the Uttarkashi, Latur and Jabalpur quakes during this decade.

CBRI's prefabricated shelters were extensively used as temporary shelters at Uttarkashi, while after the Latur quake, the institute repaired and strengthened houses in Latur, Osmanabad, Solapur and Satara.

After the Latur quake, CBRI undertook elaborate studies on the lateral strength of masonry construction, which is popular in that area.

Experiments on brick, rubble walls with several combination of mortar openings and strengthening measures have given the institute confidence in advising on repair and strengthening of damaged buildings, Iyengar said.