Context

• Data from an oil and gas exploration company has helped geologists discover a series of faults at the foot of the Himalaya.
• The international team notes that this fault system in the southeastern region of Nepal has the potential to cause earthquakes in the country.

Key Details

• The team looked at seismic reflection data, routinely collected by exploration companies looking for oil and gas.
• In this method, seismic waves are produced by small explosions at multiple sources, and many recorders called geophones record the sound echoing off layers beneath the
• The faults we detected don’t appear to extend into India, but seismic waves from an earthquake occurring on them might affect regions of India near the border… other similar faults might be present elsewhere along the southern edge of the Himalaya and might extend beneath northern India. We don’t currently have access to data that would help us explore this.

Back to Basics

What are Faults? 

• The fault is a planar or gently curved fracture in the rocks of Earth’s crust, where compressional or tensional forces cause relative displacement of the rocks and it may range in length from a few millimetres to thousands of kilometres. 
• It allows the blocks to move relative to each other and this movement may occur rapidly, in the form of an earthquake or may occur slowly in the form of creep.
• During an earthquake, the rock on one side of the fault suddenly slips with respect to the other. The fault surface can be horizontal or vertical or some arbitrary angle in between.

Types of faults 

A)Strike-slip faults-It indicates that rocks are sliding past each other horizontally, with little to no vertical movement. Both the San Andreas and Anatolian Faults are strike-slip.

B)Normal faults create space-It is described as a normal fault when one side of the fault moves downward with respect to the other side.

• These faults are “normal” because they follow the gravitational pull of the fault plane, 
• The Basin and Range Province in North America and the East African Rift Zone are two well-known regions where normal faults are spreading apart Earth’s crust.

C)Reverse faults-It is also called thrust faults, slide one block of crust on top of another. These faults are commonly found in collisions zones, where tectonic plates push up mountain ranges such as the Himalayas and the Rocky Mountains. Strike-slip faults are usually vertical, while normal and reverse faults are often at an angle to the surface of the Earth.