abnormally dangerous activity.An undertaking that necessarily carries with it a significant
risk of serious harm even if reasonable care is used, and for which the actor may face strict
liability for any harm caused; esp., an activity (such as dynamiting) for which the actor is held
strictly liable because the activity (1) involves the risk of serious harm to persons or property, (2)
cannot be performed without this risk, regardless of the precautions taken, and (3) does not
ordinarily occur in the community. • Under the Restatement (Second) of Torts, determining
whether an activity is abnormally dangerous includes analyzing whether there is a high degree of
risk of harm, whether any harm caused will be substantial, whether the exercise of reasonable care
will eliminate the risk, whether the activity is a matter of common usage, whether the activity is
appropriate to the place in which it occurs, and whether the activity’s value to society outweighs
its dangerousness. Restatement (Second) of Torts § 520 (1977). — Also, esp. formerly, termed
extrahazardous activity; ultrahazardous activity. See strict liability under LIABILITY. [Cases:
Negligence 305. C.J.S. Negligence §§ 176–179.]