The 9.0 Tohoku earthquake damaged thousands of buildings when it ripped through Japan four years ago. Much of that debris is gone now, but the broken buildings had an invisible effect, too: the earthquake released thousands of tonnes of ozone-destroying greenhouse gases into the air.
The chemicals, called halocarbons, came from old insulation, refrigerators, and electrical equipment damaged in the quake. Air quality monitoring stations recorded a major spike in halocarbon emissions in 2011. In a paper published in Geophysical Research Letters, scientists estimate that these "extraordinary halocarbon emissions" from the earthquake added up to 6,600 metric tonnes of gases.
The emissions included chemicals that had been phased out, demonstrating the long lingering effects of actions from decades ago. The American Geophysical Union's press release ticks down the list of dangerous chemicals:
These include chlorofluorocarbons like CFC-11, a powerful ozone-depleting chemical used in foam insulation until it was phased out in 1996, and hydrochlorofluorocarbons like HCFC-22, an ozone-depleting refrigerant that is also a powerful greenhouse gas and is in the process of being phased out of use. Among other halocarbons released by the earthquake were hydrofluorocarbons, or HFCs, and sulfur hexafluoride, both potent greenhouse gases.
A devastating earthquake has immediate and obvious effects, but it can have invisible and insidious ones, too, resurrecting dangerous chemicals we'd long forgotten about. [Geophysical Research Letters, AGU]
Image credits: National Institute for Environmental Studies