A major, 7.0-magnitude earthquake struck in western China near the border with Kyrgyzstan on Tuesday, according to the United States Geological Survey.

The temblor happened at 2:09 a.m. China time, data from the agency shows.

As seismologists review available data, they may revise the earthquake’s reported magnitude. Additional information collected about the earthquake may also prompt U.S.G.S. scientists to update the shake-severity map.

An aftershock is usually a smaller earthquake that follows a larger one in the same general area. Aftershocks are typically minor adjustments along the portion of a fault that slipped at the time of the initial earthquake.

Aftershocks can be of equal or larger magnitude to the initial earthquake, and they can continue to affect already damaged locations.