Designing Safe House in an Earthquake Prone Area

Designing Safe House in an Earthquake Prone Area
India on account of unique geo-physical setting is highly prone to earthquakes of varying intensities. The country has faced several devastating earthquakes in the past resulting in a large number of deaths and severe property damage. During the last century, five earthquakes measuring M8 or more had struck different parts of the country; Great Assam earthquake (1897), Kangra earthquake (1905), Bihar-Nepal earthquake (1934), Andaman-Nicobar earthquake (1941) and Assam earthquake (1950) had caused untold misery to the affected community and enormous damage to infrastructure and public and private property. In the recent years damaging earthquakes had been experienced in different parts of the country (Table 1) e.g. Assam (1988) M7.2, Bihar- Nepal (1988) M6.5, Uttarkashi (1991) M6.6, Latur (1993) M6.4, Jabalpur (1997) M6.0, Chamoli (1999) M6.8 and Bhuj (2001) M6.9. Some of the earthquake events (Muzaffarabad earthquake, 2005 M7.6; Great Sumatra earthquake, 2004 M9.1), which did occur outside Indian Territory, had a very severe bearing on the nation as well. Table -1, shows region wise frequency of occurrence of earthquakes for last 110 years.
Seismic Zoning
The country has been classified into different zones indicating the intensity of damage or frequency of earthquake occurrences. These zoning maps indicate broadly the seismic coefficient that could generally be adopted for design of buildings in different parts of the country. These maps are based on subjective estimates of intensity from available information on earthquake occurrence, geology and tectonics of the country. The Indian seismic zoning is a continuous process which keeps undergoing changes as more and more data on occurrence of earthquakes becomes available.
Considering the recorded history of earthquakes in the country, seismologists have classified 59% of the land mass of India as prone to earthquakes of different magnitudes - 11% in very high risk zone V, 18% in high risk zone IV and 30% moderate risk zone III. The capital cities of Guwahati and Srinagar are located in seismic zone V, while national capital of Delhi is in zone IV and the mega cities of Mumbai, Kolkata and Chennai are in zone III. 38 cities with population of half a million and above each and a combined population of million are located in these three regions.
List of Indian standards dealing with Earthquake resistant construction are:

1. IS 1893 (Part 1): 2002 'Criteria for Earthquake Resistant Design of Structures : Part 1 General provisions and Buildings'
2. IS 1893 (Part 4): 2005 'Criteria for Earthquake Resistant Design of Structures : Part 4 Industrial Structures Including Stack Like Structures'
3. IS 4326:1993 Earthquake Resistant Design and Construction of Buildings - Code of Practice
4. IS 13827:1993 Improving Earthquake Resistance of Earthen Buildings - Guidelines
5. IS 13828:1993 Improving Earthquake Resistance of Low Strength Masonry Buildings - Guidelines
6. IS 13920:1993 Ductile Detailing of Reinforced Concrete Structures Subjected to Seismic Forces - Code of Practice
7. IS 13935:1993 Repair and Seismic Strengthening of Buildings - Guidelines

The following links give brief guidelines for constructing safe houses in various areas lying in different seismic zones of the country and also about retrofitting etc.

• Earthquake Emergency Survival Guide
• Earthquake Preparedness Guide
• Simplified guideline for all new buildings in the seismic zone III of India
• Simplified guideline for all new buildings in the seismic zone IV of India
• Simplified guideline for all new buildings in the seismic zone V of India
• Model guidelines for development & building construction including safety provisions for natural hazards in rural areas.
• Guidelines for repair, restoration and retrofitting of masonry buildings in earthquake affected areas of Jammu & Kashmir
• Self assessment of earthquake damageability of residential brick buildings in NCT of Delhi (also in NCR)
• Seismic assessment of brick masonry buildings situated anywhere in seismic zone IV of India
• Simple retrofitting for improving earthquake resistance of brick masonry buildings in NCT of Delhi and the NCR
• Guidelines for repair, restoration, condition assessment and seismic strengthening of masonry buildings
• Rapid visual screening of RCC buildings
• Rapid visual screening of masonry buildings
• Seismic evaluation and strengthening of reinforced concrete buildings
• Conditions assessment of buildings for repair and upgrading
• National programme for capacity building of architects in earthquake risk management (NPCBAERM)
• National programme for capacity building of engineers in earthquake risk management (NPCBEERM)