Aftershock

noun (countable)

/ˈɑːftəʃɒk/

A smaller earthquake that follows a larger main seismic event (the mainshock), originating near the same focus as the initial rupture. Aftershocks result from the gradual readjustment of crustal stress along a fault after a major rupture, and can persist for days, weeks, or even years. In disaster management, aftershocks complicate search-and-rescue operations and cause additional structural collapses in already-weakened buildings; the 2015 Gorkha earthquake (Nepal/India) generated over 300 aftershocks of magnitude ≥ 4.0 within 30 days.

✍️ Usage in a UPSC answer

The National Disaster Management Authority's standard operating procedures mandate that rescue teams in Seismic Zone V regions continue wearing helmets and hard hats for 72 hours following a major earthquake, given the high probability of damaging aftershocks.

Synonyms

seismic sequelsecondary tremorpost-seismic eventconsequent tremorresidual shock

Antonyms

foreshockmainshockseismic quiescence

🌱 Word Family

aftershock (noun), aftershocks (noun plural), foreshock (noun), mainshock (noun), microseismic (adjective)

🔡 Root

Old English æfter = behind, later + Middle English schok = sudden jolt; compound formed in English

📜 Etymology

The compound 'aftershock' is a native English formation, first recorded in seismological literature in the late 19th century as instrumental seismology developed. 'After' derives from Old English æfter (behind, following), while 'shock' entered English from Middle French choc (collision, blow), itself from Old High German scoc (shake). The term became standardised in earthquake science following the 1906 San Francisco earthquake, when systematic cataloguing of post-mainshock events began.

🧠 Memory Hook

Think of AFTER + SHOCK: the earth has had its main shock, and AFTER it keeps sending smaller shocks as the fault 'settles down', like a table wobbling after you slam it hard. The 'after' in the word is your cue — it always comes after the big event.

⚠️ Disaster Management 📖 Seen in: Disaster Management — Framework, Prepa...

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