Earthquakes in Himalayas
Why it Matters?
On August 15, 1950, a magnitude 8.6 earthquake — the strongest on land — struck Assam’s Mishmi Hills, devastating Northeast India and Tibet. It caused massive landslides, floods, and over 1,500 deaths in India. Originating at the Eastern Himalayan Syntaxis, it revealed the region’s complex tectonics and extreme seismic vulnerability.
What You Should Know?
The Himalayas were formed due to continental–continental collision between the Indian Plate and the Eurasian Plate ~50 million years ago.
Indian Plate still moves northward at ~5 cm/year, causing stress accumulation.
Region falls in Seismic Zones IV & V (as per BIS classification), indicating very high earthquake risk.
The region is dominated by thrust faults such as the Main Central Thrust (MCT), Main Boundary Thrust (MBT), and Himalayan Frontal Thrust (HFT).
Earthquakes are mostly shallow-focus (<70 km), thrust-type, and highly destructive.
Seismic gaps like the Central Himalayan Gap and Kumaon–Garhwal Gap indicate high potential for future great earthquakes.
Historic events include Kangra (1905, M 7.8), Bihar–Nepal (1934, M 8.0), Assam–Tibet (1950, M 8.6), Sikkim (2011, M 6.9), and Gorkha–Nepal (2015, M 7.8).
Impacts include landslides, river damming, flash floods, and increased GLOF (Glacial Lake Outbursta Floods) risk.
Cause of earthquake
Earthquakes are caused due to release of energy.
The release of energy occurs along a fault. A fault is a sharp break in the crustal rocks.
Rocks along a fault tend to move in opposite directions. As the overlying rock strata press them, the friction locks them together.
Types of earthquake
The earthquakes are divided into three zones: shallow, intermediate, and deep based on their depth which range between 0 – 700 km.
Shallow earthquakes have a focus 0 – 70 km deep.
Intermediate earthquakes have a focus 70 – 300 km deep.
Deep earthquakes have a focus 300 – 700 km deep.