Monday’s earthquake in Manipur, near India’s border with Myanmar, occurred in an area where the India and Eurasia tectonic plates — the slabs of planet that created the highest mountains in the world — collide.
The two continental plates are coming together at a rate of 40 millimeters to 50 millimeters a year, producing large numbers of earthquakes that make the region one of the most seismically volatile on Earth, according to the U.S. Geological Survey.
On the surface, the boundary between the plates is marked by the foothills of the Sulaiman Range in the west, and the Indo-Burmese Arc in the east and the part of the Himalaya Front in the north of India.
The earthquake Monday was generated by what is known as a strike-slip fault, where sections of the Earth move like two blocks rubbing alongside each other at vertical, or nearly vertical, fracture points.
The exact direction of the movement that produced the 6.7-magnitude quake isn’t so far known, but initial analysis of the seismic waveforms by the U.S.G.S suggests it was either the result of a right block–known as the right-lateral fault plane–dipping slightly to the east-northeast, or a left block dipping steeply to the south-southeast.
The precise location of the fault where movement triggered the quake isn’t known, the U.S.G.S. said, but is broadly related to this plate boundary deformation at a depth of close to 31 miles, within the lithosphere, or Earth’s crust and upper mantle, of the India plate.
Moderate to large earthquakes around the northeast of India are fairly common, the U.S.G.S. said. Some 19 other quakes greater than magnitude 6 have occurred within 156 miles of Monday’s temblor in the past 100 years, it said.