A secondary fall or collapse that occurs after an initial fall, or additional material falling after the main avalanche or collapse.
From 'after' plus 'fall' (from Old English feallan). Geological and mining terminology describing secondary avalanches or structural collapses.
In mining disasters, the initial cave-in looks catastrophic, but the real killer is often the afterfall—tons of rock that come loose hours later from the destabilized tunnel walls.
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