May 3, 2013, by Tim Radford
A victim of Sandy: A replica of the British vessel HMS Bounty goes down
Image: US Coast Guard
FOR IMMEDIATE RELEASE The energy released by 2012’s Superstorm Sandy in the US was so immense that it triggered seismic waves which registered on equipment designed to detect earthquakes. LONDON, 3 May – Sandy, the superstorm that all but submerged New York, was powerful enough to set US earthquake detectors quivering long before it hit the American coastline. It stirred up Atlantic Ocean waves that slammed into each other, started to shake the sea floor and then shook the Midwestern states so vigorously that the storm’s progress could be tracked by seismometer. The windstorm-induced tremors were very tiny, and not unusual – and say as much about the sensitivity of modern seismometers as about the furious forces released in a superstorm. But the episode – revealed at a recent meeting of the Seismological Society of America in Salt Lake City, Utah – is a reminder that the energies released by the dangerous mix of swirling winds and warm oceans are dramatic and, with global warming, could become even more frequent and more devastating. “We detected seismic waves created by the ocean waves both hitting the East Coast and smashing into each other”, said Keith Koper, of the University of Utah seismic stations. And his colleague and fellow author of an as-yet-unpublished study, Oner Sufri, a doctoral student, said “As the storm turned west-northwest, the seismometers lit up.” Sandy began in the Caribbean, developed into a hurricane – the largest Atlantic hurricane on record – and killed 285 people in seven countries, as well as causing an estimated $75 billion in damage. It hit 24 US states and swept into New York on 29 October, by then classified as a superstorm.
Hurricanes generate phenomenal energies. One calculation is that the total energy released through clouds and rain during the average hurricane is about 200 times the capacity of all the world’s power stations. Another more graphic calculation is that during its lifespan, the average hurricane releases the energy of 10,000 nuclear bombs. Some of this marine mayhem was picked up by an array of 500 portable detectors called Earthscope. These were first placed in California in 2004, and have been leap-frogging eastwards across the US. When Sandy developed, most of them were located in a band between Minnesota and east Texas, and Lake Erie and Florida. They were designed to tune in, a bit like a doctor’s stethoscope, to the Earth’s crust and the mantle below. Sandy in effect helped geophysicists explore the fabric of the continental US – but the tiny tremors in the crust also told the researchers about the progress of a storm far away. Hurricanes become a predictable hazard as ocean surface temperatures rise, and in 2012 seas off the east coast of the US were unusually warm. Sandy was classified a very unusual event, a once-in-a-century storm, but researchers have warned that, as global temperatures rise, such storms could develop as often as every other year. – Climate News Network
Tim Radford, a founding editor of Climate News Network, worked for The Guardian for 32 years, for most of that time as science editor. He has been covering climate change since 1988.