A two-story residential structure under construction collapses from an engineering error. This could be considered which type of collapse?

The scenario described refers to a two-story residential structure that collapses due to an engineering error. This type of collapse can be classified as a moderate collapse.

A moderate collapse typically involves substantial structural failure but does not reach the extremes of catastrophic or heavy collapses, which can often affect multiple levels of a building or cause it to become completely uninhabitable. In the case of a two-story construction, if the engineering error leads to a part of the structure giving way or the overall integrity being compromised, it reflects a failure that is significant enough to be classified as moderate.

Light collapses tend to involve minor structural failures, such as components falling without causing overall disintegration. Basic or surface collapses usually refer to superficial issues that can be easily remedied without extensive damage. Heavy collapses would imply a more catastrophic failure, usually involving significant structural components and severe implications for safety.

Thus, identifying this collapse as moderate aligns with the understanding that while serious, it does not represent the maximum degree of failure where the entire structure has been rendered completely unsafe or lost.