Tsunami myths could be solved by mathematics
Published: February 23, 2006
A little over a year after the devastating tsunami struck, mathematicians claim that maths could possibly explain some of the misconceptions and myths about these deadly waves and potentially help in saving lives.
“Mathematics is particularly well suited to defining the possibilities and limitations for a tsunami early warning system,” says Dr. Craig, the Canada Research Chair for Mathematical Analysis and its Applications, at McMaster University in Hamilton, Canada.
“Predicting earthquakes is a grand challenge problem that’s presently beyond us. But predicting a tsunami’s potential based on these earthquakes is a doable problem and I think mathematicians can play an important role in this,” says Dr. Craig.
Mathematics, he says, has a key role to play in dispelling mistaken assumptions about these waves. One such popular belief is that a tsunami’s first wave surge is always the biggest. “It’s not necessarily the biggest crest in front,” he cautions. “For example, in Sri Lanka the biggest crest was the third or fourth.” In one case, he says, a vacationing British geologist at one Sri Lankan resort noted the initial modest, non-destructive surge and warned staff and tourists to clear the beach before the arrival of the larger, deadly surges.
He says that because of differences in depth, the evolution of a tsunami is different in different ocean basins. For example, the Boxing Day tsunami travelled twice as fast in the deeper Indian Ocean than in the Andaman Basin. Tsunami waves are distinguished from ordinary wind-generated ocean waves by their great length between peaks, often exceeding 200 kilometres in the deep ocean, and by the long amount of time between these peaks, ranging from 15 minutes to an hour.
It’s the length and width of tsunamis, rather than their at-sea height that reveals their massive power, according to Craig. The Indian Ocean tsunami had a crest length of about 1,200 kilometres. The surges that inundated the Sri Lankan coast were parts of waves that were a stunning 100 kilometres from crest to trough, but in mid-ocean were less than one metre in amplitude.
Dr. Craig has currently begun work with McMaster University mathematics colleagues Drs. Bartosz Protas and Nicholas Kevlahan to apply mathematical tools from meteorological forecasting to understand the generation of large tsunamis from major earthquakes.
While better advanced warning systems can help in many cases, Dr. Craig says his immersion in tsunami science has shown him that a tsunami’s speed and power sometimes can defy an early warning system. With a wave traveling at 700 kilometres an hour, his advice is, “If you feel an earthquake, go to higher ground.”
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