Hawaii spill reminder of 1919 “Boston Molasses Disaster”

(Source: Boston Public Library)

The news is full of images of the 230,000 gallons-molasses spill endangering marine life in Hawaii.

But this isn’t the first time a flood of the sticky substance has caused havoc in the United States.
The so-called Boston Molasses Disaster began on January 15, 1919, when a 50-foot-high tank full of molasses collapsed into Boston’s North End. The broken tank spilled 2.3 million gallons into the streets, killing 21 people and injuring 150.

Ferris Jabr writing in Scientific American suggests why the flood of the sweet syrup was so deadly: “Fluid dynamics explains why it was even more devastating than a typical tsunami.”

A wave of molasses does not behave like a wave of water. Molasses is a non-Newtonian fluid, which means that its viscosity depends on the forces applied to it, as measured by shear rate. Consider non-Newtonian fluids such as toothpaste, ketchup and whipped cream. In a stationary bottle, these fluids are thick and goopy and do not shift much if you tilt the container this way and that. When you squeeze or smack the bottle, however, applying stress and increasing the shear rate, the fluids suddenly flow. Because of this physical property, a wave of molasses is even more devastating than a typical tsunami. In 1919 the dense wall of syrup surging from its collapsed tank initially moved fast enough to sweep people up and demolish buildings, only to settle into a more gelatinous state that kept people trapped.

H/T Kristin Miller