Three fires since the start of June have highlighted the threat that lightning poses in the North Dakota oil patch.
In each case it was the tanks that store the toxic saltwater associated with drilling that were to blame, not the oil wells or drilling rigs.
The silo-like storage tanks are made of or lined with fiberglass because it holds up better against the corrosive liquid than metal-only tanks would. Fiberglass tanks don't release the heat from lightning strikes as well as metal ones would, contributing to the fires.
North Dakota doesn't require companies to install lightning protections at the storage and disposal sites, although many do so anyway. Protections are no guarantee, though, as they were in place at two of the three sites set ablaze since June 1.