Seismic gap
Topic: Interior of the Earth: Earthquakes, Volcanoes and the Layered Earth · NCERT: Beyond NCERT
Meaning
A seismic gap is a stretch of an active fault that has had no big earthquake for a long time. Stress keeps building along all of an active fault. Where the rock has not slipped for many years, the stress has not been released. So a large quake there is thought likely. The idea helps decide where to focus preparation, building rules and monitoring.
Example
The "central seismic gap" in the Himalaya lies between the areas that ruptured in the 1905 Kangra and 1934 Bihar-Nepal quakes. It covers Uttarakhand and western Nepal. This is a worry because the region has growing towns and hydropower projects.
Don't confuse with
- Shadow zone: this is an area on the earth's surface where seismographs record no direct waves from a particular earthquake. A seismic gap is a quiet stretch of a fault where a future quake is expected.
Related concepts
- Alpine-Himalayan belt
- Assam-Tibet earthquake (1950)
- Gorkha earthquake (2015)
- Turkey-Syria earthquake (2023)
- Myanmar earthquake (2025)