Retired researcher suggests unexploded dynamite may have caused Töölö accident

A retired researcher from VTT, Engineer Jouko Törnqvist, suggests that the cause of the recent accident in Töölö may be related to a rock drill striking an unexploded charge. Dynamite is commonly used as an explosive in rock blasting near populated areas. Prior to an explosion, holes are drilled into the rock to place the explosives. It is possible that not all dynamite charges detonate at once, and this may go unnoticed. When new holes are drilled, the drill bit can accidentally strike a leftover explosive.

“Yes, it’s sufficient to trigger an explosion if the drill hits,” Törnqvist states. However, he emphasizes that these views are purely speculative, as information regarding the incident remains limited.

Ville Estlander, a duty fire chief from the Helsinki Fire Department, shares a similar perspective. Preliminary assessments indicate that the construction site had conducted rock blasting earlier in the summer, and an unexploded charge might have been left in a hole drilled for subsequent blasts.

According to Törnqvist, dynamite used in rock blasting can generally be considered a safe explosive. Factors such as sunlight or vibration will not trigger it. Törnqvist has researched the vibrations caused by blasting and has served as a witness in legal disputes related to building damage.