Steps needed to create a plan for earthquake risk reduction are:-
1. evaluation,
2. planning, and
3. implementation.
First, the evaluation must be realistic by reflecting the local conditions.
The planning stage involves identifying effective alternatives or solutions, selecting the best alternatives and developing them into an action plan.
The last stage, the implementation process, applies the results of the evaluation and planning processes.
After this comes collection of information required for assessment:
Data is to be collected on
A. Seismic hazard
B Exposure to hazard
- life
- property
- business / function ( including information on revenue, data, market share and reputation / image)
C. Vulnerability Assessment
Based on above data a Risk Analysis has to be done.
For finding the solution, we should think about which Mitigation method to follow. These can be:
1. Structural
2. Locational
3. Operational
4. Risk Transfer
Mitigating earthquakes is a much broader field than simply designing for earthquakes. Mitigation is a several-stage planning and management process which involves
(1) estimating the potential losses that earthquakes might cause
(2) deciding if the potential losses are acceptable or not
(3) if not, examining alternative loss reduction techniques, which involves identifying the effectiveness of each alternative in reducing losses and the associated cost.
(4) setting some criteria for deciding which alternative is the most effective, such as benefit-cost, lives saved, least regret, or other paradigms, and applying the criteria to select the most effective package of alternatives.
(5) developing a design and implementation program for the package of alternatives.
Experience would show that the following factors or contexts are necessary prerequisites for the instrumentation of adequate risk management strategies and procedures. Some or all of these may be used in constructing management .
Bhuj city map and details
Current population of Bhuj is 184,429, mainly people live in the outskirts of the city,but as of now they are residing into the city and the city is also developing well since people from many countries come for study earthquake assessment and many other historical places resembling Mohan jo daro and other things. there are small businesses and factories, about half of each in weak masonry and older reinforced concrete buildings. Zone B also contains the schools, electric generating plant, the major telephone and radio broadcast stations, City Hall and other vital infrastructure (except the port), all of which are older reinforced concrete buildings
Mostly there are earthen buildings in and Old masonry RC buildings at the outskirts of the city, counting of houses is not possible as it deems into an venture of glooming places, though in the main taluk , there are better construction with enhanced work.
Though bhuj is not a industrial city hence there are not many industries , there are small businesses and factories, about half of each in weak masonry and older reinforced concrete buildings. Some of the industries set up are of mineral and allied industries. Bhuj is a famous destination for shopping of handicraft work. Artists of nearby villages bring their art work for sale in Bhuj. Important landmarks for people wishing to study and know more about Kutchi embroidery are Shrujan, Kutch Mahila Vikas Sangathan (KMVS), Kalaraksha and Women Artisans' Marketing Agency (WAMA, Bandhini. Krantiguru Shyamji Krishna Verma Kachchh University is located in Bhuj. University has 28 colleges affiliated, seven of them are in Bhuj
There are walls within walls, attractive crenellated gateways, old palaces with intricately carved wooden pavilions, and striking, brightly decorated Hindu temples. Bhuj resembles much of India before the tourist invasion.
Bhuj was within 20km of the fault break, and suffered very severe damage during the earthquake . The palace complex is in the old walled city. It consists of a collection of buildings in a variety of styles, dating from the 18th century. Some of the buildings are of random masonry construction, and have suffered extensive damage and collapse.
art of the north east corner of the perimeter walls, about 2m wide, have collapsed. The central three pairs of timber columns on the north side are tilted outwards (ie north) by about 5% to 7.5% (figure 14b), pushing the flat roof strip on this side about l50mm across the top of the external wall, which is also sloping outwards, but only by about 3%. The opposite wall is leaning by about the same amount in the same direction. The timber columns on all four corners of the grid are vertical; the other columns have a variety of tilts up to 2%, but usually much less. There is no evidence of structural distress in the timber columns; one member of the roof truss is bowed and slightly split at one point, but generally there is no other sign of structural distress or of material deterioration in the timber. The central roof slab has sagged very significantly, probably between trusses.Swami narayan temple was also devastated
Thus many of the historical structures have been disrupted, though retrofitting method was used to strengthen the structures. This was the only way to enable most of damaged buildings including hospitals to restore back as this procedure was a bit expensive but total cost benefit analysis was taken before the work started.
Violent ground shaking was felt in Bhuj for nearly 85 seconds with several minutes of lower level shaking. There are major earthquake faults near Bhuj , Slippage is believed to have occurred on the south dipping North Wagad reverse fault in the failed rift. This has been further confirmed by aftershock studies following the earthquake. Initial speculation held the Kutchh Mainland Fault (KMF) responsible, however, further studies and field observations show that it might have been caused on the previously unknown NWF lying in the vicinity of the KMF. Slip is believed to have totaled between 1 metre to 4 metres.
Vulnerability is the propensity of things to be damaged by a hazard. People’s lives and health are at risk directly from the destructive effects of the hazard. Their incomes and livelihood are at risk because of the destruction of the Buildings, crops, livestock or equipment which these depend on. Each type Of hazard puts a somewhat different set of elements at risk The next step is to understand the vulnerability of buildings and infrastructure to these earthquake hazards. Earthen (e.g., adobe) and masonry (stone or brick) buildings are typically the most vulnerable to shaking. Local experience is a good guide to what is vulnerable in a society, and the list of potentially vulnerable elements should be supplemented by a study of written reports and the knowledge (often never recorded) of those who lived through previous disasters.
The buildings most badly damaged in the earthquake were earthen buildings ,old masonry buildings and simple reinforced concrete frame buildings . The statistics of damage from the earthquake identified the vulnerability of a range of building type characteristics to earthquakes of different strength likely to occur in the future. By identifying buildings with high vulnerability factors ,where these buildings also have large
numbers of residents, they will contribute both to casualties if they collapse, and to homelessness if they become uninhabitable. The buildings with highest projected future earthquake losses are graded into primary and secondary priority for attention.
Mitigation measures
include engineering measures to build more hazard-resistant structures, physical planning to locate important facilities away from hazards, economic measures to protect earnings, management structures to ensure protection measures are carried through and societal measures to encourage the public to support mitigation measures. Measures like establishing building codes for new construction, strengthening existing buildings, land-use controls, and improving
preparedness planning are generally costly to apply, whether it is
individuals, private companies or the general tax-payer who will ultimately
be responsible.
Proper implementation, monitoring and sustainability of the ERRP is very necessary as lack in attention would deprive a heavy loss to the system, ERRPs may be developed by different persons or organizations, depending on how the risk arises, and who bears the risk. Typically, within an organization, persons responsible for the facilities will develop an ERRP – this might be the engineer of a school district or the manager of facilities for a company. They may develop the ERRP themselves, or retain experts to develop the ERRP for them. All the efforts and time invested in evaluating the earthquake risk of a city and defining action plans to manage that risk will be wasted if nothing is actually implemented. Throughout the risk management project, several activities have to be carried out to set up the political, legal, financial, and cultural conditions that will facilitate the implementation of the plans and programmes prepared by the project and, most importantly, promote the institutionalization of earthquake risk management in the city. Among these activities are the following:
• Incorporation of all the community sectors in the project: representatives of the institutions and sectors of the community should have an active participation throughout the project
• Proper information and dissemination of results: effective collaboration with the mass media throughout the project should be promoted so that the whole community is properly informed about what the project is doing for the city and what the project results are
• Search for funding: strong efforts to generate funds, especially local funds, have to be made by approaching the industrial, commercial and financial sectors of the community as well as international aid organizations with offices in the country
• Creation of an organization to coordinate risk management activities: an organization must be selected (or created if a suitable one does not exist) to coordinate, monitor, and advocate risk management efforts in the city .
