Why India has earthquakes: plates, faults and seismic zones

Why does India have earthquakes, and what does it mean when a map puts a place in a particular seismic zone? The answer begins with the movement of the Indian plate. It also means learning to read earthquake information carefully. A plate's speed, a zone number and a magnitude label tell us different things. Keeping them separate helps us understand the geology and the official guidance, especially when versions of a zoning map seem to disagree.

The ground belongs to a moving plate

The land beneath us is part of a much larger structure. NCERT describes tectonic plates as rigid slabs of lithosphere, made up of the crust and the uppermost mantle. They move over the asthenosphere. A plate can include both continental and oceanic material. Its outline need not follow a continent's coastline.

The National Center for Seismology, or NCS, places the Indian subcontinent on the Indian plate. Its glossary gives the plate's average movement as approximately 5 centimetres a year. Read this as a rough average for the plate, rather than a speed shared by every place in India or every Himalayan fault.

When reading about an earthquake, start with this wider view. The moving plate helps explain the setting of the place where the earthquake is reported.

A collision that still matters

NCERT dates India's collision with Asia to about 40 to 50 million years ago and links it to the uplift of the Himalayas. This rough timescale describes the collision's history; the mountain-building process continues.

The collision between the Indian and Eurasian plates continues. The Delhi Disaster Management Authority identifies it as the reason for earthquake activity in northern India, including the Himalayas. Colliding rocks can store energy before slipping. The same continuing process connects the mountains' long history with earthquake activity today.

Keep both timescales in view. The age of the collision tells us how this setting developed. Continuing plate movement explains why it remains active today.

Beyond the Himalayan picture

The Himalayan collision is a major part of India's earthquake story, but the geography extends beyond it. The CSIR National Geophysical Research Institute identifies an Andaman subduction zone to the east as well as the Himalayan collision zone to the north. These are distinct tectonic settings.

The institute also points to major earthquakes within the continental shield region. This matters when thinking about peninsular India. An old or comparatively stable continental region can still experience a major earthquake, even far from the Himalayan collision.

To understand India's earthquakes, then, look at both the Himalayan collision and activity elsewhere. Together, they give a fuller picture of where earthquakes occur.

What the four zones mean

The Bureau of Indian Standards, or BIS, seismic zoning map in IS 1893 (Part 1):2016 uses four zones: II, III, IV and V. The National Disaster Management Authority, or NDMA, explains this framework in its September 2021 simplified guidelines for earthquake safety of buildings.

In that explanation, the zones correspond to shaking intensities on the MSK scale. Zone II corresponds to intensity VI or less, Zone III to VII, Zone IV to VIII, and Zone V to IX or more. Zone V is the most severe category in this framework.

Read the Roman numerals as zone labels: Zone V does not mean magnitude 5. Zone II still has an earthquake hazard. Use the national map as a broad guide, rather than a prediction of the exact shaking at an individual building.

When reading a map, keep its title and legend beside the colours. Check the standard's year and what each category means. Include that context when you copy a zone label, so that someone else can understand it too.

Why a newer map may not be the current one

The map's version matters here. BIS announced IS 1893 (Part 1):2025 as a seventh revision, with a map based on probabilistic earthquake-hazard assessment and provisions referring to Zones II through VI. That announcement explains why a reader may encounter material containing Zone VI.

Then check what happened after that announcement. A Ministry of Earth Sciences parliamentary answer, issued through the Press Information Bureau on 1 April 2026, states that the revised zonation was withdrawn in March 2026 and that the map in IS 1893 (Part 1):2016 remains the current standard.

This is the latest clear official statement of the map's status found in research checked on 2 October 2026. On that evidence, use the 2016 map as the current standard. The April answer dates the withdrawal to March, without giving an exact day.

Follow a standard's status as well as its publication year. To find which version remains in use, read the newer announcement alongside any later official updates.

Keep the magnitude scale's name

Magnitude reporting needs another kind of care. The NCS glossary distinguishes several magnitude scales and identifies moment magnitude, written Mw, as the preferred scale for large earthquakes. Use the name Richter only when the source identifies that scale.

When repeating an earthquake report, keep the scale label supplied by the reporting agency. If the label is Mw, keep it. If the source leaves the scale unspecified, leave it unspecified in your account too. This simple habit keeps your wording faithful to the information the source provides.

Keep the report separate from the zoning map, too. A magnitude label describes something different from a seismic zone. The NDMA map groups zones by shaking intensity.

Reading the next report

Start with a few checks. Which plate setting is being discussed? Which standard and year does the map cite? Which magnitude scale does the agency name? For a zoning claim, read the original announcement and check later official updates on its status. Use these answers to explain the report clearly, keeping the same level of certainty as the source.

For further exploration of scientific concepts, Learnacy Labs offers browser-based interactive experiments across subjects including physics and mathematics. Its guided Understand, Explore and Prove flow lets users change inputs and watch the readouts respond.