Write a note on seismic zones of India.

The official zoning

• The governing code is IS 1893 (Part 1) on earthquake-resistant design; the current map divides India into four zones: II, III, IV, and V.
• Zone I was dropped in later revisions because even the peninsula is not treated as non-seismic; Zone II is now the lowest mapped hazard.
• Zone V is the highest intensity belt; Zone IV is high; Zone III moderate; Zone II low. Design horizontal acceleration coefficients rise from II to V.

Geography of the zones

• Zone V covers the Kashmir Himalaya, Himachal and Uttarakhand high hills, the entire North-East, the Rann of Kutch, and the Andaman and Nicobar Islands — regions of plate boundary or known great earthquakes (Shillong 1897, Kangra 1905, Bihar–Nepal 1934, Assam 1950, Bhuj 2001, Kashmir 2005).
• Zone IV includes Delhi, parts of western Uttar Pradesh, Bihar, the remaining Himalayan foothills, the Koyna–Warna belt, and stretches of the west coast and Jammu.
• Much of the Deccan and eastern coastal plain falls in Zones II and III, yet Koyna (1967) after the reservoir and Latur (1993) show that moderate zones can still produce deadly shallow shocks.
• Uttar Pradesh is mostly Zones III and IV, with the Himalayan north and some western districts more exposed than the eastern plains.

Why the note matters for policy

• The National Disaster Management Authority and state disaster authorities use the map for building by-laws, hospital and school retrofitting, and the National Building Code.
• Himalayan thrust earthquakes can exceed magnitude 8; Kutch and the Andamans add intra-plate and subduction risk.
• Microzonation of cities such as Delhi and Guwahati is a finer layer on the national four-zone map, because local soil can amplify shaking inside the same BIS zone.