Which event is NOT a primary cause of structural fires?

Earthquakes are not typically categorized as primary causes of structural fires. While an earthquake can lead to fires, such as through ruptured gas lines or structural damage to electrical systems, it is considered more of a contributing factor rather than a direct cause like cooking accidents, electrical failures, or unattended open flames.

Cooking accidents often lead to fires due to careless handling of hot oils or open flames, making them a major cause of structural fires. Electrical failures frequently result in short circuits or overheating, which can ignite surrounding materials. Unattended open flames, such as candles or fireplace embers, can easily lead to fires if they’re not monitored.

In contrast, the relationship between earthquakes and fires is more indirect, making the impact of an earthquake on fire incidence less straightforward than the other listed causes, which are direct actions that can precipitate a fire immediately.