Concept of earthquake risk management

Concept of Earthquake Risk

ReductionBy

S.AhmedFaculty Head, DMC,

Meghalaya Administrative Training Institute

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

To understand Earthquake Risk

“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.”

Dr. Roger Bilham of Colorado University had warned the policy makers in 2006:-

“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

According to Dr.Harsh Gupta, former Director of National Geophysical Research Institute, Hyderabad,

Felt earthquakes recorded at CSO Shillong during 2010-2011

Seismicity of India (1505 to March,2010) (M>5.0)

Rising Trend of Number of Earthquakes per year

The Probability of a Major Earthquake is----?

HIGH

Magnitude?

About 8 on the Richter Scale

Warning for the North-East

Disaster Risk

= Hazard X Vulnerability

Vulnerability – Social, Economical, Physical, Structural

Earthquake Disaster Risk

Map showing Earthquake Zones in India

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

Magnitude Vrs Intensity

IntensityMagnitud

e

Intensity

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

IX MSK Intensity Earthquake

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

X MSK Intensity Earthquake(≈8R)

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?!!

For Meghalaya – for Shillong?

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 State's border with Assam, the site of the Great Shillong earthquake of 1897.

Seismic Hazard

Epicentre of 1897 Earthquake

Intensity of 1897 Earthquake

“Mexican – hat” of greatest intensity

mapped by Oldham

Intensity IX – 30,000 sq miles

Intensity X – 11,000 sq miles

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

1897 Eq.-Epicentre near Mendipathar; depth of Focus not

known

Seismic Risk for Shillong Plateau

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. In this region earthquakes come with landslides, flood and along with series of smaller magnitude earthquakes.

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

1897 - Earthquake effects in Epicentral Tract

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

Earthquake effects in Epicentral Tract (contd)

Seismic Risk for Shillong and Meghalaya

INTENSITY IX may be adopted as the minimum level of Risk

Provided Vulnerability does not increase

Earthquake effects

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

How do we measure Risk?

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

Risk & Vulnerability

Earthquake Disaster Risk Raj Bhavan before the 1897 Earthquake

Stone Masonry structure

Raj Bhavan destroyed in 1897 earthquake


All Saints Church before 1897 Earthquake


All Saints Church destroyed by 1897 earthquake


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

Acknowledgement

Building which withstood 1897 Earthquake

Present Official Residence of D.C., Tura, constructed around 1867 but renovated

Building which withstood 1897 Earthquake

Residence of Late Amjad Ali, Laban, Shillong

Structure which has withstood a hundred years

Present Day All Saints Church

Structure which has withstood a hundred years

RAJ BHAVAN rebuilt in 1904

Most Vulnerable House

A Stone Masonry House in Sohra

2001 Census

Structure with least risk- at least in an Earthquake

Bamboo- thatch houses

Not very Vulnerable

The Iing Sad at Smit, Meghalaya, constructed by the King of Hima Khyriem, in 1928

Disaster Risk - low

Assam Type Houses

Disaster Risk is Higher

Gujarat Earthquake, 2001Well built house in

tact

Pancake collapse due

to poor design &

construction

Earthquake Disaster Risk Reduction – NDMA Guidelines

All new construction to comply with earthquake-resistant building codes and revised town planning bye-laws, land use zoning, Development Control Regulations & building codes

Earthquake-Resistant Design & Construction of New Structures

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


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


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


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


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

Seismic Strengthening & Retrofitting of Lifeline & Priority Structures

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


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.


State Government Buildings Buildings of Central Government Offices/

Organisations Legislatures High Courts Cantonment Private Buildings

Urban Building Profile

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

Urban Building Profile- Categories

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

Urban Building Profile- Building Materials

Prioritization for Structural Safety Audit

1. Raj Bhavans, Legislatures, High Courts, State Secretariats, Power Plants, Water Works, Heritage Buildings

2. Schools & Colleges, and Hospitals3. Reservoirs & dams, bridges, bus stations4. Office of the D.C. & S.P.; Financial Institutions5.Multi-storeyed buildings with five or more

floors in residential apartments, office and commercial complexes

Guidelines of National Disaster Management Authority

Rapid Visual Screening

Detailed Vulnerability Assessment

Structural Safety Audit-NDMA

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

Structural Safety Audit-NDMA

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

Seismic Vulnerability Assessment

A standardized procedure for vulnerability assessment will be prepared at the national level………………………in line with the relevant national standards

NDMA Guidelines for Seismic Vulnerability Assessment

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

Regulation & Enforcement-NDMA

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

Design Codes-NDMA

(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

Design Codes-NDMA

Trained Professionals1. Human Resource with competence in

Seismic Vulnerability Assessment of built environment is required

2. Practical training by experienced firms in actually assessing seismic safety of a building can be given to professionals

3. Testing Equipments required

Seismic Vulnerability Assessment

Trained Professionals (Capacity Building)

1. Experienced and competent Professionals/ Organisations in the Govt. as well as in the private sector are required

2. Capacity of existing professionals are to be built up

Retrofitting of Buildings

1. Different organisations and professional bodies to be consulted to clarify process and issues involved

2. Capacity of professionals to be developed under National Earthquake Mitigation Project??

NDMA Guidelines for Seismic Retrofitting

Techno-Financial Regime1. Financial Loan for retrofitting/

strengthening of building with subsidy on interest rate may be given

2. Refund of loan & interest may be treated in same way as Housing Loan in Income Tax Rules

Retrofitting of Buildings

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.

Demolition of Unsafe Structure

Trained Professionals Experienced and competent

Professionals are required for demolition without causing any disaster.


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


Safety of Buildings with Mobile -phone Towers?

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

Insurance

NDMA Guidelines– other structures will be insured against losses during future earthquakes, while undertaking seismic retrofitting of critical and lifeline structures

Insurance

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

Mitigation Fund

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

Financial Allocation-NDMA

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

Techno-Financial Regime- NDMA

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

Construction in Rural & Semi-Urban Areas- NDMA

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

Awareness and Preparedness- NDMA

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?

Awareness and Preparedness- NIDM

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

Awareness and Preparedness

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

Capacity Building

‘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

Medical Preparedness

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

Medical Preparedness

Disaster Risk

= Hazard X Vulnerability - Capacity

Disaster Risk Reduction

THANK YOU

Education

Concept of earthquake risk management