Earthquake Disaster Risk Index
Port town Ratnagiri is at a high risk for casualties in the event of an earthquake, an Earthquake Disaster Risk Index (EDRI), released earlier this month, has found.
The report, prepared by the National Disaster Management Authority (NDMA), indicates that while Mumbai and Pune are in the medium-risk category, high density of population makes them susceptible to “high exposure”. The EDRI also indicates that about 56 per cent area of India is prone to moderate to severe earthquakes.
- The NDMA, along with International Institute of Information Technology (IIIT), Hyderabad, has prepared EDRI for 50 cities and one district on a pilot basis in seismically active zones around the country. The risk levels for casualties have been graded as low, medium and high.
- According to the index, Ratanagri is observed to have third highest risk at 69 per cent among all cities in seismic zone IV, after Shimla and Panipat.
- Ratanagri has 40 percent of reinforced concrete sample buildings that fall in “collapse” category. According to the index, the city has multi-storey buildings with the ground floor open for parking or other purposes, and are not designed for earthquakes. Also, buildings touching or located close to adjacent ones are seemingly unsafe.
- The cities were selected for the pilot study based on the population density, housing threat factor and if they were identified as smart cities. Seismically active regions in India, that is, seismic zones IV and V, were the main focus of the study.
- The report was prepared on the basis of field visits to 25 cities and collection of secondary data from the remaining cities. Among 50 cities, 13 cities were found to have high risk, 30 with medium and the remaining seven with low risk level.
- It was observed that among 13 cities with high risk level, seven cities have high hazard level. Aizawl, Solan, Gangtok and Vijayawada are the four cities which have high exposure among the 13 high-risk level cities.
- Similarly, Ghaziabad, Pune and Mumbai are three cities which have higher exposure among 30 cities with medium risk level.
- According to EDRI, cities with high risk and high vulnerability include Shimla, Aizwal, Pithoragarh, Nainital, and Uttarkashi; and medium risk with high vulnerability are Darbhanga, Patna, Mandi and Chennai.
- Using a combination of physical surveys on ground and risk assessment, the team also recorded vibration data on selected buildings.
- This was then fed into computer modelled buildings to simulate the effects of earthquakes of varying intensities to quantify physical damage to buildings during earthquakes.
- The risk, which is initially estimated of individual building typology in a city, was eventually projected onto the city using the Census data of total number of buildings in that city of that typology. The project also aims to increase general awareness about earthquake safety and to make homes earthquake resilient.
- The report also observes that one way is to educate architects and engineers is by putting in place an adequate framework for new buildings, determining the risk of existing buildings and suggesting techniques for reinforcing them.