The fire department reckons that a blockage caused a buildup of methane in the toilet. When the woman sat on the toilet, the methane started to accumulate in the bowl.
The explosion was caused by a faulty lightswitch – it sparked, and exploded the methane.
The woman suffered third degree burns to both legs, and large cuts from the exploding porcelain. The bar was in Barcelona’s historic Barri Gothic area, in calle Ample.
(The photo above is entirely gratuitous.)