Magnitude versus Intensity - Civil Technocrats 05, 2013 · Collapse of random rubble masonry walls in a house. Notice the RC roof slab. 56 1991 Uttarkashi Earthquake

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Indian Seismicity and Past Earthquakes

Sudhir K Jain

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Outline

• Hazard versus Disaster

• Epicentral Map and Seismic Zones

• Some Great Indian Earthquake

• Some Recent Indian Earthquakes

• Magnitude vs Frequency of Occurrence

• Implications

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Earthquake hazard

• Potential of earthquake occurrence and the potential for losses

• Cannot mitigate or reduce earthquake hazard

• Need to evaluate earthquake hazard

• Questions such as

– When and where to expect a damaging earthquake

– Size and other characteristics of expected earthquake

– Expected ground motion characteristics at site (may be with a certain probability of occurrence)

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Earthquake Disaster

• Negative fall-out of earthquake occurrence on society

• Man-made construction primary cause for disaster

• Can (and must) reduce earthquake disaster

• Earthquake disaster depends on– Earthquake characteristics

• Size, location, focal-depth, …

– Ground response (global and local)• Attenuation with distance, local site effect, ….

– Response of man-made facilities• Housing, transport, communication, …

– Response of people / Post-earthquake handling• Victims, neighbours, officials, …

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World Seismicity

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Plate Boundaries

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Epicentral Map of India

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Indian Seismic Zone Map

Seven Seismic Zones: 0, I, II, III, IV, V, VI

IS:1893-1962

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Seven Seismic Zones: 0, I, II, III, IV, V, VI

IS:1893-1966

INDIAN SEISMIC ZONE MAPS…

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Five Seismic Zones: I, II, III, IV and V

IS:1893-1970

IS:1893-1975

IS:1893-1984


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Four Seismic Zones: II, III, IV, V

IS:1893 (Part1) - 2002


Some Great IndianEarthquakes

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Some Great Indian Earthquakes

• Earthquakes of Magnitude >8

– 1819 Cutch Earthquake (M8.3)

– 1897 Assam Earthquake (M8.7)

– 1905 Kangra Earthquake (M8.6)

– 1934 Bihar-Nepal Earthquake (M8.4)

– 1950 Assam Earthquake (M8.7)

• Observations

– India prone to Great Earthquakes

• Four M>8 events in 53 years

– No M>8 earthquakes in last 50 years

– 2001 Bhuj earthquake (M7.7) to be seen in this light

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1819 Cutch Earthquake

• Runn of Cutch

– West coast of India

– Away from plate boundaries

• Perhaps strongest intra-plate event in world

– Motion perceived even at Calcutta

• First clear occurrence of faulting during earthquakes

– Allah Bund : Fault scarp ~100 km long ~3m high

• Low population area

– Death toll ~1500 lives

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1897 Assam Earthquake

• Amongst greatest earthquakes of world

– Magnitude 8.7

– Mean radius of perception : 900 miles

– Mean radius of area of serious damage: 300 miles

– Longest dimension of meizoseismal area: 160 miles

• Chendarang fault

– 12 miles long, throws up to 35ft

– Surface distortion

• Upthrow of objects

• Liquefaction in alluvial plain of Brahmputra

• Effects in meizoseismal area provided model for Modified Mercalli Intensity XII

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1897 Assam Earthquake…

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Upthrow of Boulders (from Oldham)

>1g acceleration

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Bent Rails at Rangapara, Tezpur-Balipara Tramway

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Manshai Bridge

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1897 Assam Earthquake:

• Stone Buildings

– Leveled to ground

• Ekra-built Buildings

– Wooden framework with walls of san grass covered in plaster

– About half the buildings leveled to ground

– Significant damage due to stone chimneys

• Plank Buildings

– Wooden framework covered with planks

• No damages

– Led to development of “Assam-Type” houses

– Current housing status

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before the 1897 Assam Earthquake

Government House, Shillong

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after the 1897 Assam Earthquake

Government House, Shillong

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1905 Kangra Earthquake

• 4 April 1905

• Magnitude 8.6

• About 19,000 lives lost

– Very low population density

• Maximum Intensity X around Kangra

– Intensity at Dehradun VIII

– Intensity between Kangra and Dehradun up to VI/VII

– Initially thought of as two different earthquakes

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1934 Bihar-Nepal Earthquake

• 15 January 1934

– Around 2:13pm

• Deaths

– 7253 in India and 3400 in Nepal

• Magnitude 8.4

• Maximum intensity X in about 8020 miles

– Intensity X also at Munger and in Kathmandu Valley (about 100 miles from main damage area)

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1934 Bihar-Nepal Earthquake…

• Slump Belt

– 190 mile long, up to 40 miles wide

– Excessive liquefaction

– Buildings slumped into alluvium

– Subsidence of embankments (roads/rails)

– Uplift of bottoms in tanks

– Fissures / emissions of sand and water

•one fissure : 15’ deep, 30’ wide, 900’ long!

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• Why more damage and strong shaking at Munger and in Kathmandu valley in 1934 Bihar-Nepal Earthquake?

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1950 Assam-Tibet Earthquake

• Magnitude 8.7

• Epicenter near Rima (Tibet)

• Maximum intensity XII

• Aftershocks M 7.0

– More property loss in Assam than in 1897 earthquake

• Massive landslides

– Blockade of rivers

– Later, led to floods as dams burst one by one

Some Recent IndianEarthquakes

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Some Recent Indian Earthquakes

• Moderate Earthquakes (M~6.5)

– 1967 Koyna

– 1988 Bihar-Nepal

– 1991 Uttarkashi

– 1993 Killari

– 1997 Jabalpur

– 1999 Chamoli

• Large Earthquake (M~7.7)

– 2001 Bhuj

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1967 Koyna Earthquake

• Magnitude ~ 6.5

• Maximum Intensity VIII

• Deaths: 200; Injuries: 1500

• Area considered non-seismic (Zone I of the prevalent zone map)

• Damage to dam, houses, other structures

• One strong motion record

– In the gallery at mid-height of the dam

– Peak vertical acceleration 0.3g

– Peak horizontal acceleration 0.45g & 0.39g

– Record not very reliable (faint)

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1967 Koyna Earthquake…

• Koyna Dam

– 103 m high concrete gravity type

– Designed for 5%g (static load)

– Damaged, but not disastrous

• Reservoir-Induced Seismicity

• Changes in seismic zone map

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1988 Bihar-Nepal Earthquake

• 21 August 1988 at 4:39am

• Magnitude 6.6

• Maximum Intensity VIII

• Deaths: 1004; Injuries: 16000

– Summer time; Most people outdoors

• Same damage trend in Munger and Kathmandu as in 1934 earthquake

• Damage to buildings and bridges

– Shaking induced

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• Liquefaction

– Nominal

– Damage to embankments

• Damage in Darjeeling and Sikkim

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Collapse of two-storey cycle stand-cum-canteen at ITI Darbhanga.

Ground storey was RC frame construction, upper storey was of brick walls

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Collapse of cycle stand-cum-canteen at ITI

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Collapse of a Wall in Darbhanga

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Collapse of a boundary wall in Darbhanga

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Collapse of jack-arch roof at Hamidia Madarsa in Darbhanga: killed several children and adults

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Damage to mumty in a 2-storey residential building in Munger

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Damages to arches:

Notice the jack-arch roof

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Damage to a T-Beam Bridge in Sikkim

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Damage to a T-Beam Bridge in Sikkim

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1991 Uttarkashi Earthquake

• 20 October 1991 at 2:52am

– Winter morning; most people indoors

• Magnitude 6.6

• Maximum intensity ~ VIII+

• 768 dead; 5,066 injured

– Very low population density in the area

• Excellent strong motion records

– Peak ground acceleration ~ 0.3g

• Collapse of a modern and vital bridge

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1991 Uttarkashi Earthquake…

Collapsed Gawana Bridge at Uttarkashi

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Collapse of Retaining Wall

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Damage to Road

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Damage to Road

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Typical suspension bridge in Garhwal Himalayas

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Collapse of anchor block in a suspension bridge

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• Stone walls and RC roof

– Total collapses

– Major loss of life

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Collapse of random rubble masonry walls in a house. Notice the RC roof slab.

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Collapse of random rubble masonry walls in a house.

Another view

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• Load-bearing constructions at ITBP campus

– Located in intensity area VIII+

– Only nominal damage

– Good quality of construction Load-bearing

• 2-storey houses at Maneri colony

– Nominal earthquake-resistant features

– Located in intensity area VIII+

– Some damage; no loss of life

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Residential Buildings at ITBP Campus

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Residential Building at Maneri Colony

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• RC Frame Buildings

– Uttarkashi

•State Bank of India: Collapse

•Post Office: Structural damage

•Hotels: hardly any damage

– Dehradun

•ONGC Buildings: structural and non-structural damage

•Other buildings: no reported damages

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Collapse of top storeys in 3-storey RC frame State Bank of India Building

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Collapse of top storeys in 3-storey RC frame State Bank of India Building

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Practice of leaving inadequate dowel lengths for future extension: Collapse of top two storeys in State Bank of India Building was caused by this practice

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Practice of leaving inadequate dowel lengths for future extension: Collapse of top two storeys in State Bank Building was caused by this practice

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Shear failure of columns in 2-storey RC frame Post Office at Uttarkashi

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Collapse of infill walls in the generator room at Maneri Hydro Power Plant

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Collapse of infill walls in the generator room at Maneri Hydro Power Plant

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Women's Polytechnic of ONGC Dehradun

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Ground Floor Plan

Plans of Women's Polytechnic at ONGC, Dehradun

First Floor Plan

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1993 Killari Earthquake

• Magnitude 6.4

• Maximum Intensity VIII-IX

• Death toll ~10,000– Up to 35% in some villages

– Earlier estimates up to 30,000

• Surface rupture– Intra-plate earthquake

• Located in Seismic Zone I of the prevalent zone map!

• Astonishingly good rescue and relief – After 2 days

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1993 Killari Earthquake…

Location of Killari Earthquake and the prevalent Seismic Zone Map

Killari

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• Damage in a limited area

– 20 km20 km

– No towns

– Few modern structures

• Major cause of casualty in houses

– Stone masonry in mud mortar

– Very heavy roof

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Collapse of Stone Masonry Houses

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Collapse of Stone Masonry Houses

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Collapse of a Prefabricated Building

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Collapse of an RC Elevated Water Tank at Kautha

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• Damage was concentrated in a small area

– Very shallow focus earthquake

– Depth of focus ~ 5 km (as against 20-40 km)


Influence Region

Large focal depthMore affected area,

Less intensity

Small focal depthLess affected area,

High intensity

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1997 Jabalpur Earthquake

• Magnitude 6.0

– 4:22am on 22 May 1997

• Maximum intensity

– VIII in a couple of villages

– VI–VII in Jabalpur town

• Seismic Zone III

– Corresponding intensity VII

– Experienced design level shaking!

• About 38 persons died, 350 injured

– Early morning hours in summer

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1997 Jabalpur Earthquake…

• First time in India, moderate earthquake close to a city (12 lakh population)

• Most RC frame buildings

– Good performance!

– Damages in RC frame buildings with open ground storey

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• Himgiri Apartments

– Five-storey RC frame building

– Shops at first storey on two faces of building (brick infills)

– Remaining corner for parking (no brick infills)

– All upper storeys: apartments (brick infills)

– First storey columns in parking area badly damaged

•Buckling of longitudinal bars, snapping of ties, spalling of cover, and crushing of core concrete

– Damage in upper storeys very minor

•Small cracks in the filler walls

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Himgiri Apartments

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Himgiri Apartments

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Himgiri Apartments

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Himgiri Apartments

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Ajanta and Nalanda Apartments

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Ajanta and Nalanda Apartments

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Youth Hostel Building

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Youth Hostel Building

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• Performance of 2-3 storey masonry houses:

– Mumty damages

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Mumty collapse in Gun Carriage Factory Campus

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Extensive damage to mumty in hundreds of load-bearing masonry houses in several government campuses. This one is in Telecom Colony

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Repair of cracks by stitching with RC blocks, at Telecom residential colony

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Repair of cracks by stitching with RC blocks, at Telecom residential colony

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Damage to a Pucca house in Kosamghat. Kosamghat had the maximum shaking intensity VIII on MSK scale. Here, roof is in reinforced brick, walls in brick masonry in mud mortar.

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Damage to a Pucca house in Kosamghat. Kosamghat had the maximum shaking intensity VIII on MSK scale. Here, roof is in reinforced brick, walls in brick masonry in mud mortar. CLOSE-UP VIEW

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Damaged kuchcha house in Amzar, near Mehgaon dam. The roof of this house collapsed.

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1999 Chamoli Earthquake

• Magnitude 6.5

• Maximum intensity VIII at a few locations

• Significant site effects

• Seismic zone V

– Corresponding intensity IX and above

• About 100 died, about 400 injured

• Lesser damage than in Uttarkashi EQ

• Performance

– Lintel band buildings

– RC frame buildings

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Collapse of stone masonry house. Notice the RC roof slab.

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Collapse of one wythes in a traditional house in slate wafer masonry.

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Partial collapse in a random rubble stone masonry. Note, the front portion has RC beam supported on concrete block columns and roof consists of RC slab.

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A two-storey house in concrete block masonry with lintel band in Bheematala (Intensity VII). The house did very well even through quality of construction was poor. Roof projection sustained damage as the reinforcement in the cantilever portion was incorrectly placed on bottom face.

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Two-storey house at Pipalkoti with no damage. Ground storey in slate wafer masonry, upper storey added later in concrete block masonry. Both storeys have RC lintel band.

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Brick masonry house in Chamoli earthquake affected area. Notice the RC columns, RC beams, and the discontinuous lintel band. It is not unusual in the area to see RC beams between lintel and roof with RC slab supported on masonry.

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Tarang apartments in Patparganj area of Delhi. An

eight storey building with soft ground storey. During Chamoli earthquake, sustained cracks in masonry infill walls and separation of masonry infill from RC frame in the ground storey.

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Tarang apartments in Patparganj area of Delhi.

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Shastri Bhawan in New Delhi. Six brick fins of height collapsed in this 5-storey block due to shaking caused by the Chamoli Earthquake, 1999

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Debris of fallen fins at Shastri Bhawan in New Delhi due to 1999 Chamoli earthquake.

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Telephone exchange building in Dehradun. RC

columns had brick facia for architectural reasons. Separation cracks developed in the columns at the junction of concrete and masonry.

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2001 Bhuj Earthquake

• Magnitude 7.7

• Maximum MSK Intensity X

– Bhuj in Seismic Zone V of Indian seismic map

• 8.46 am on 26 January 2001

– ~13,805 dead; 1,67,000 injured

– 300,000 houses destroyed; 700,000 houses damaged

• Numerous multistorey RC buildings collapsed

– 130 such buildings collapsed in Ahmedabad ~225km from epicenter

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VIII

X

VII

2001 Bhuj Earthquake…

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2001 Bhuj Earthquake…

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Earth Dams (2001 Bhuj)

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Rail and Road Embankment (2001 Bhuj)

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Bridges (2001 Bhuj)

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Buildings (2001 Bhuj)

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CD of Photo Images

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CD of Bhuj EQ Report

In Closure…

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• Recurrence of Earthquakes

– World average:

•For every event of M>8.0, ~ 100 M>6.0 events

– India:

•High frequency of great earthquakes

•Low frequency of moderate earthquakes

– Moderate earthquake create awareness and lead to improvements in construction at “low” human cost.

– In the last 50 years, no M>8.0 earthquakes

– Performance of buildings and infrastructure not satisfactory in recent Indian earthquakes

Implications

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Implications…

– Orders of magnitude more constructions today than in 1897 or 1934

– Major Indian cities vulnerable

• e.g., New Delhi (Seismic Zone IV) prone to great Himalayan events and moderate local events

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Long-term human response to EQ

Stage Time EventReaction

Positive Negative

1 0-1 minuteMajor Earthquake

Panic

2 1 minute – 1 weekAftershocks Rescue and Survival Fear

3 1 week – 1 monthDiminishing aftershocks

Short term repairs Allocation of blame – builders, designers, officials, etc.

4 1 month – 1 yearLong term repairs, and action for higher standards

5 1 year – 10 years Diminishing interest

610 years

– The next time

Reluctance to meet costs of seismic provisions, research, etc. Increasing non-compliance with regulations

7 The next timeMajor Earthquake

Repeat stage 1-7

Key, 1988

Thank you…

Documents

Magnitude versus Intensity - Civil Technocrats 05, 2013 · Collapse of random rubble masonry walls in a house. Notice the RC roof slab. 56 1991 Uttarkashi Earthquake