‘余震’ (yú zhèn) literally means ‘remaining shake’ — ‘余’ (yú) means ‘remaining,’ ‘leftover,’ or ‘surplus,’ and ‘震’ (zhèn) means ‘shake,’ ‘tremor,’ or ‘earthquake.’ Together, they refer specifically to smaller earthquakes that occur after a larger mainshock in the same region. These are caused by the crust adjusting to the stress changes from the initial event and can continue for days, weeks, or even years.

Aftershocks are an important concept in seismology and disaster response. While usually weaker than the mainshock, strong aftershocks can cause additional damage, especially to already weakened buildings, and pose ongoing risks to survivors and rescue workers. In Chinese media and official reports, ‘余震’ is used formally and technically — you’ll hear it frequently in earthquake coverage, safety bulletins, and scientific communication.