Concept of earthquake risk management


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Shri S Ahmed is the Faculty Head of the Disaster Management Centre of the Meghalaya Administrative Training Institute, Shillong. A Retired Engineer, he continues to share his expertise in the filed of Disaster Management. This is one of the Presentations used to spread awareness on the concept of Earthquake Risk Management.

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Concept of earthquake risk management

  1. 1. By S.Ahmed Faculty Head, DMC,Meghalaya Administrative Training Institute
  2. 2.  We need to study :- Frequency of earthquakes in the region The probability of a particular magnitude of earthquake occurring The Vulnerability of the area under consideration
  3. 3.  “Our findings show that great earthquakes- those with a magnitude of 8.2 or greater – can re- rupture Himalayan regions that already have ruptured in recent smaller earthquakes, or those with a magnitude of 7.8 or below”. “The current conditions might trigger at least four earthquakes greater than 8.0 magnitude, but if they delay, the strain accumulated during the centuries provokes more catastrophic mega earthquakes.”
  4. 4.  “Moderate magnitude to great earthquakes in the northeast India region is found to be preceded, generally, by well defined earthquake swarms and quiescence periods” Based on this, Dr. Gupta made specific predictions in 1986- the 7.5 R magnitude Indo-Myanmar earthquake which occurred in 1988
  5. 5.  The Probability of a Major Earthquake is----? HIGH Magnitude? About 8 on the Richter Scale
  6. 6.  Disaster Risk= Hazard X Vulnerability Vulnerability – Social, Economical, Physical, Structural
  7. 7.  Magnitude of an earthquake is a measure of the energy released at the focus Intensity is the effect caused by the earthquake at a particular place Magnitude of earthquake is same no matter which observatory measures it Intensity usually reduces with distance from the epicentre
  8. 8. Magnitude Intensity
  9. 9.  7R≈ IX MSK intensity earthquake, at epicentral area; General panic among people, damage to furniture, animals run to & fro in confusion and cry; General damage to buildings occur, large cracks in walls of R.C.C. buildings are seen; chimneys break or fall off; and many stone masonry houses collapse; Cracks of about 10 cm width are seen in the ground; Landslides occur; old dry wells become renewed and existing wells may dry up
  10. 10.  General Destruction of buildings Gaps in walls, parts of many R.C.C. buildings may collapse; Most of stone masonry houses totally collapse; Critical damage to dykes & dams; severe damage to bridges; underground pipes brake Cracks in the ground of width upto 1.0 metres may occur; Considerable landslides possible; new lakes occur
  11. 11.  Intensity of Earthquake? It is unpredictable! Where will the Epicentre be? At what depth will the focus of the earthquake be? What will the Vulnerability be then?!!
  12. 12.  According to a hazard map by the Global Seismic Hazard Assessment Programme and other scientific studies, the State can expect to have a peak gravitational acceleration (PGA) of 0.24g to 0.48g. The region where the highest PGA can be expected is along the States border with Assam, the site of the Great Shillong earthquake of 1897.
  13. 13. Intensity IX –30,000 sq miles Intensity X – “Mexican – hat” of11,000 sq miles greatest intensity mapped by Oldham
  14. 14.  Area of greatest earthquake intensity= 3.5 x size of Meghalaya Area of greatest earthquake intensity= 40 x size of Shillong City Epicentral distance ≈100 km
  15. 15. In the Shillong plateau, the focal depth is mostly within 60 km. The prominent structural discontinuities in the plateau are Dudhnai, Kulsi, Samin, Dawki and Dhubri faults and Dapsi and Barapani thrusts.Here earthquakes of upto MM intensity IX can be expected. Inthis region earthquakes come with landslides, flood and alongwith series of smaller magnitude earthquakes.
  16. 16.  Ground was fissured & sand vents spewed fountains of sand Many Streams changed courses River Brahmaputra affected causing floods Bed of River Krishnai subsided and Lake Dekachang formed (15km long x1.5 km) Landslides occurred- hills stripped of forest for 30 km
  17. 17.  Vertical movement of 10m at Chedrang Fault Telegraph poles displaced by about 5 metres Many houses sank, due to liquefaction of soil during earthquake, with roof only visible Geography changed TYPICAL DESCRIPTION OF INTENSITY XII
  18. 18.  INTENSITY IX may be adopted as the minimum level of Risk Provided Vulnerability does not increase
  19. 19.  Risk is the expected loss, in terms of : Number of people who may die Number of people who may be affected Number of buildings/structures likely to collapse Services likely to be disrupted Loss in monetary terms
  20. 20.  Risk = ∲ F, D, P, L, VV F – Frequency of disaster D- type of disaster P- Probability of occurrence L- Level of Disaster (Intensity) VV – Value of Vulnerable Elements L = ∲ ( V) V- Vulnerability of Elements that are affected
  21. 21. Stone Masonry structure
  22. 22. Stone Masonry structure
  23. 23. Stone Masonry structure
  24. 24. Stone Masonry structure
  25. 25.  Pictures are taken from the book “From Residency to Raj Bhavan- History of the Shillong Government House” by Imdad Hussain, and published by Regency Publications, 20/36-G, Old Market, West Patel Nagar, New Delhi 110008
  26. 26. Residence of Late Amjad Ali, Laban, Shillong
  27. 27. Present Day All Saints Church
  28. 28. RAJ BHAVAN rebuilt in 1904
  29. 29. A Stone Masonry House in Sohra
  30. 30. 2001 Census
  31. 31. Bamboo- thatch houses
  32. 32. The Iing Sad at Smit, Meghalaya, constructed by the King of Hima Khyriem, in 1928
  33. 33. Assam Type Houses
  34. 34. Well builthouse in tact Pancakecollapse due to poor design &construction
  35. 35.  All new construction to comply with earthquake-resistant building codes and revised town planning bye-laws, land use zoning, Development Control Regulations & building codes
  36. 36.  Central & State Govt. to implement & enforce relevant standards for seismically safe design and construction of buildings, bridges, flyovers, ports and harbours, and other lifeline and commercially important structures Consider using incentives and disincentives, and compliance reviews
  37. 37.  State Govt/SDMA will organise capacity building programmes among professionals and masons Faculty members in engineering & architecture colleges, and polytechnics, Industrial Training Institutes, will be provided with adequate exposure
  38. 38.  State Govt. will incorporate earthquake – resistant features in standard designs of schools, primary health centres, anganwadi centres and panchayat buildings These will serve as pilot projects
  39. 39.  Design of all new buildings and structures to be scrutinised by competent authorities before issuing building approval Third party audit of the design and construction of major construction works to be undertaken
  40. 40.  Develop inventory of existing built environment Assess vulnerability of these constructions Prioritise structures found vulnerable Develop seismic retrofitting measures Undertake construction work to strengthen vulnerable structures
  41. 41.  Initial focus for structural safety audit & retrofitting will be on Govt. & public bldgs. The State Govt./SDMA to take up selected critical lifeline structures as pilot projects in a phased manner The State Govt./SDMA in consultation with their State Eq Management Committee & Hazard Safety Cell review existing built environment & prepare such lists
  42. 42.  Cluster approach to be adopted in priori- tising – building types like RCC, stone masonry,etc- primary schools, PHCs etc. – so as to encourage consultations, demonstration & possible replication.
  43. 43.  State Government Buildings Buildings of Central Government Offices/ Organisations Legislatures High Courts Cantonment Private Buildings
  44. 44.  Administrative & residential Government buildgs. Hospitals Schools Electric Power Plants Water Supply Works Telephone exchange Cinema Halls and Malls Libraries and Auditoriums Heritage Buildings Dams, Bridges, Bus Stations, Airports, etc
  45. 45.  Reinforced Cement Concrete (RCC) multi- storeyed buildings Steel Structures Timber structures (Assam Type Buildings) Buildings with a Combination of RCC & Timber Stone or brick masonry structures Houses of bamboo, tin sheets etc
  46. 46. Prioritization for Structural Safety Audit1. Raj Bhavans, Legislatures, High Courts, State Secretariats, Power Plants, Water Works, Heritage Buildings2. Schools & Colleges, and Hospitals3. Reservoirs & dams, bridges, bus stations4. Office of the D.C. & S.P.; Financial Institutions 5.Multi-storeyed buildings with five or more floors in residential apartments, office and commercial complexes
  47. 47.  Rapid Visual Screening Detailed Vulnerability Assessment
  48. 48.  Detailed methodology for RVS for different types of buildings and standardised procedure for vulnerability assessment will be prepared at the National level to clarify the process and issues involved in seismic retrofitting
  49. 49.  Techno-Legal Framework1. BIS Guidelines for Seismic Vulnerability Assessment of Structures – multi storeyed R.C.C. Framed buildings, are rquired.2. Rules & Regulations, Building Bye-Laws are required incorporating these Guidelines
  50. 50.  A standardized procedure for vulnerability assessment will be prepared at the national level………………………in line with the relevant national standards
  51. 51.  Adoption of Model Town Planning Bye- Law by State Govt. by revising existing Acts & Zoning Regulations, & Building Bye-Laws BIS will revise/update Codes in two years (i) IS: 1893(Part 2): Elevated and ground supported Liquid Retaining Structures (ii) (Part 3) : Bridges & Retaining Walls (iii) IS: 4326: Earthquake Resistant Constn
  52. 52.  BIS will place in public domain including internet for free download all IS related to seismic safety Periodic revision in 5 years Design aspects to be addressed (i) Seismic evaluation and strengthening (ii) Seismic design of tunnels (iii) Seismic design of buried and above ground pipelines
  53. 53.  (iv) Seismic design and ductile detailing of bridge piers (v) Seismic design, construction and manufacture of facilities, structures and components related to electrical power generation, transmission and distribution (vi) Seismic design and ductile detailing of steel structures, etc
  54. 54.  Trained Professionals1. Human Resource with competence in Seismic Vulnerability Assessment of built environment is required2. Practical training by experienced firms in actually assessing seismic safety of a building can be given to professionals3. Testing Equipments required
  55. 55.  Trained Professionals (Capacity Building)1. Experienced and competent Professionals/ Organisations in the Govt. as well as in the private sector are required2. Capacity of existing professionals are to be built up
  56. 56. 1. Different organisations and professional bodies to be consulted to clarify process and issues involved2. Capacity of professionals to be developed under National Earthquake Mitigation Project??
  57. 57.  Techno-Financial Regime1. Financial Loan for retrofitting/ strengthening of building with subsidy on interest rate may be given2. Refund of loan & interest may be treated in same way as Housing Loan in Income Tax Rules
  58. 58.  Techno-Legal Framework Rules & Regulations for declaring a building as unsafe and for carrying out its demolition are required District Disaster Management Authority (DDMA) has powers under the D.M.Act, 2005, to demolish structures hazardous to the public; Rules may be framed.
  59. 59.  Trained Professionals Experienced and competent Professionals are required for demolition without causing any disaster.
  60. 60.  Techno-Financial Regime Rules & Regulations for providing temporary accommodation or for giving financial help to affected persons/families may be framed National Rehabilitation & Resettlement Policy, 2007, may be extended to cover such cases or similar rules may be passed
  61. 61.  Rational Insurance Policies to cover different structures exposed to different hazards are required. NDMA Guidelines– The Insurance Sector will be encouraged to promote risk transfer mechanisms through insurance in the future Incentive to Insurers by way of deduction, of the amount of premium paid, from Income Tax, may be offered
  62. 62.  NDMA Guidelines– other structures will be insured against losses during future earthquakes, while undertaking seismic retrofitting of critical and lifeline structures
  63. 63.  D.M.Act, 2005, stipulates creation of Disaster Mitigation Fund by every State and each District D.M. Plan needs to be mainstreamed with development plan so that specific allocation of funds are made for (i) disaster preparedness, (ii) for mitigation measures, including retrofitting
  64. 64.  State Govt. to make specific allocations for carrying out disaster preparedness as well as disaster mitigation measures, including retrofitting of selected lifeline structures Corporate Sector may be asked to support mitigation measures as PPP efforts and Corporate Social Responsibility
  65. 65.  Housing development programmes supported by the GoI and State Govts (like Indira Awas Yojana) etc will be made to comply with earthquake resistant design and construction practices Disbursement of funds by banks to industrial units will also be similarly linked to compliance of safety norms
  66. 66.  State Govts to develop suitable bye-laws Local conditions to be considered State Govts to regulate all future constructions to make them earthquake resistant State Govts to issue specific illustrative guidelines for each type of public building, like panchayat offices, primary schools, etc
  67. 67.  Comprehensive awareness campaign on safe practices to be followed before, during and after an earthquake to be implemented Mobilise community to carry out earthquake mitigation measures A handbook on earthquake safety will be prepared
  68. 68.  Manual on structural safety audit of infrastructure and lifeline buildings will be prepared Translations into local languages to be undertaken Video films to be prepared Handbook for seismic strengthening & retrofitting of existing buildings to be prepared WHO WILL PREPARE?
  69. 69.  Electronic and print media will be used Different stakeholders like elected representatives, civil servants, members of local administration authorities, school administrators, members of management boards of educational institutions and hospitals, school children, etc will be targetted
  70. 70.  High quality education material will be developed Professionals to be equipped with requisite knowledge & will undergo training programmes Special programmes for physically handicapped and mentally challenged people, women and the elderly will be developed DM to be introduced in school curricula, as well at higher levels DM aspects of medical education at undergraduate level to be introduced
  71. 71.  „all hazard‟ medical management plan to be prepared Will address need to create greater awareness in all medical teams and the medical community of most frequent injuries, illness and other health problems Trained Medical First Responders to be identified
  72. 72.  All public health facilities will develop their own DM plans Mobile hospitals and Quick Reaction Medical Teams will be developed Trained trauma and psycho-social care teams to be identified Medical & paramedical staff will carry out regular exercise based on SOP
  73. 73.  Disaster Risk = Hazard X Vulnerability - Capacity