Transform fault
Topic: Continental Drift, Sea-floor Spreading and Plate Tectonics · NCERT: Class 11, Ch 4 "Distribution of Oceans and Continents"
Meaning
A transform fault is a crack where two plates slide sideways past each other. Crust is neither made nor destroyed there, but strong, shallow earthquakes happen. On the ocean floor, transform faults run roughly at right angles to a mid-ocean ridge. They cut the ridge into segments that are shifted out of line. They form because eruptions do not happen along the whole crest at the same time, so different blocks move away from the ridge at different rates. The earth's rotation also affects these separated blocks. Only the stretch of fault between the two offset ridge ends is an active plate boundary.
Example
The San Andreas Fault in California is a transform fault on land. Along it, the Pacific plate slides past the North American plate. Other examples are the North and East Anatolian faults in Turkey (2023 earthquake) and the Sagaing Fault in Myanmar (2025 earthquake).
Don't confuse with
- Thrust fault: here one rock slab is pushed up over another, as in the Himalayas' Main Central Thrust. In a transform fault, the blocks move sideways past each other, not up and over.