Technicians' Gaffe Blamed for Huge LA Explosion

Bomb crew miscalculated the 'explosive weight' of seized fireworks
By Newser Editors and Wire Services
Posted Jul 20, 2021 8:00 AM CDT
Behind Huge Fireworks Blast in LA: Technicians' Bad Math
Los Angeles Police Chief Michel Moore talks during a news conference in Los Angeles on Monday.   (AP Photo/Stefanie Dazio)

Los Angeles bomb technicians overloaded a containment chamber with homemade fireworks last month during a detonation, likely causing a catastrophic explosion that injured 17 people and rocked a neighborhood, the police chief said Monday, per the AP. Chief Michel Moore said five members of the department’s bomb squad have been removed from field duties as the investigation continues and could face discipline. The explosion—which damaged dozens of homes, businesses, and vehicles just days before July Fourth—was highly unusual, officials say, because such containment chambers are designed to withhold blasts. The bomb technicians overloaded it above the safety rating, however, even as authorities are investigating if the detonation device had a defect.

The bomb technicians—without using a scale, as is allowed by Los Angeles police procedures to avoid additional handling of the unstable devices—estimated the weight of the homemade explosives and a counter-charge to be 16.5 pounds in a standard flash powder measurement. That measurement is not the same as an item's physical weight and is instead calculated as a TNT equivalent because explosives have different concentrations and therefore have varying “explosive weights." Federal authorities who weighed the remains after the blast calculated that the weight was actually more than 42 pounds. The incident has prompted the Los Angeles Police Department and FBI to review police protocols regarding the detonation of explosives.

(More fireworks stories.)

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