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Earthquake hazard zoning map of India

Earthquake zones of IndiaFrom Wikipedia, the free encyclopedia

The Indian subcontinent has a history of devastatingearthquakes. The major reason for the highfrequency and intensity of the earthquakes is that theIndian plate is driving into Asia at a rate ofapproximately 47 mm/year.[1] Geographical statisticsof India show that almost 54% of the land isvulnerable to earthquakes. A World Bank & UnitedNations report shows estimates that around 200million city dwellers in India will be exposed tostorms and earthquakes by 2050.[2] The latestversion of seismic zoning map of India given in theearthquake resistant design code of India [IS 1893(Part 1) 2002] assigns four levels of seismicity forIndia in terms of zone factors. In other words, theearthquake zoning map of India divides India into 4seismic zones (Zone 2, 3, 4 and 5) unlike itsprevious version which consisted of five or six zonesfor the country. According to the present zoningmap, Zone 5 expects the highest level of seismicitywhereas Zone 2 is associated with the lowest level ofseismicity.

Contents

1 Center for Seismology2 Zone 53 Zone 44 Zone 35 Zone 26 Zone 17 See also8 Notes9 External links

Center for Seismology

Center for Seismology, Ministry of Earth Sciences is nodal agency of Government of India dealing withvarious activities in the field of seismology and allied disciplines. The major activities currently beingpursued by the Center for Seismology include, a) earthquake monitoring on 24X7 basis, including realtime seismic monitoring for early warning of tsunamis, b) Operation and maintenance of nationalseismological network and local networks c) Seismological data centre and information services, d)Seismic hazard and risk related studies e) Field studies for aftershock / swarm monitoring, site responsestudies f) earthquake processes and modelling, etc.[3] The MSK (Medvedev­Sponheuer­Karnik) intensitybroadly associated with the various seismic zones is VI (or less), VII, VIII and IX (and above) for Zones

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2, 3, 4 and 5, respectively, corresponding to Maximum Considered Earthquake (MCE). The IS codefollows a dual design philosophy: (a) under low probability or extreme earthquake events (MCE) thestructure damage should not result in total collapse, and (b) under more frequently occurring earthquakeevents, the structure should suffer only minor or moderate structural damage. The specifications given inthe design code (IS 1893: 2002) are not based on detailed assessment of maximum ground accelerationin each zone using a deterministic or probabilistic approach. Instead, each zone factor represents theeffective period peak ground accelerations that may be generated during the maximum consideredearthquake ground motion in that zone.

Each zone indicates the effects of an earthquake at a particular place based on the observations of theaffected areas and can also be described using a descriptive scale like Modified Mercalli intensityscale[4] or the Medvedev–Sponheuer–Karnik scale.[5]

Zone 5

Zone 5 covers the areas with the highest risks zone that suffers earthquakes of intensity MSK IX orgreater. The IS code assigns zone factor of 0.36 for Zone 5. Structural designers use this factor forearthquake resistant design of structures in Zone 5. The zone factor of 0.36 is indicative of effective(zero period) level earthquake in this zone. It is referred to as the Very High Damage Risk Zone. Theregion of Kashmir, the western and central Himalayas, North Bihar, the North­East Indian region and theRann of Kutch fall in this zone.

Generally, the areas having trap rock or basaltic rock are prone to earthquakes.

Zone 4

This zone is called the High Damage Risk Zone and covers areas liable to MSK VIII. The IS codeassigns zone factor of 0.24 for Zone 4. The Indo­Gangetic basin and the capital of the country (Delhi),Jammu and Kashmir fall in Zone 4. In Maharashtra, the Patan area (Koyananager) is also in zone no­4.In Bihar the northern part of the state like­ Raksaul, Near the border of India and Nepal, is also in zoneno­4 that "almost 80 percent of buildings in Delhi will yield to a major quake and in case of anunfortunate disaster, the political hub of India in Lutyens Delhi, the glitz of Connaught Place and themagnificence of the Walled City will all come crumbling down."

Saket Suman of The Statesman reported on New Delhi's proximity to a major quake in his report [6][7]

Zone 3

The Andaman and Nicobar Islands, parts of Kashmir, Western Himalayas fall under this zone. This zoneis classified as Moderate Damage Risk Zone which is liable to MSK VII. and also 7.8 The IS codeassigns zone factor of 0.16 for Zone 3.

Zone 2

This region is liable to MSK VI or less and is classified as the Low Damage Risk Zone. The IS codeassigns zone factor of 0.10 (maximum horizontal acceleration that can be experienced by a structure inthis zone is 10% of gravitational acceleration) for Zone 2.

Zone 1

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Since the current division of India into earthquake hazard zones does not use Zone 1, no area of India isclassed as Zone 1.

Future changes in the classification system may or may not return this zone to use.

See also

List of earthquakes in IndiaGeology of India

Notes1. "Earthquake Hazards and the Collision between India and Asia". Retrieved 2006­05­13.2. "Indian cities under threat of storms & earthquakes by 2050: World Bank & United Nations". The Times OfIndia. 2011­12­09.

3. http://www.imd.gov.in/section/seismo/static/welcome.htm4. "Vulnerability Zones in India". Retrieved 2006­05­13.5. "Lessons learned from the Gujarat earthquake ­ WHO Regional Office for South­East Asia". Retrieved

2006­05­13.6. http://epaper.thestatesman.com/489813/SECTION­II/30­04­2015#dual/1/17. http://www.thestatesman.com/news/voices/wrecked­ship­in­a­wild­sea/60339.html#u1YIrBMzdHsp1lSo.99

External linksIndia Meteorological Department (http://www.imd.gov.in/main_new.htm)

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Categories: Earthquakes in India Geology of India Disaster preparedness in IndiaGeographic areas of seismological interest Seismology Seismic zones by country

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