According to scientists at the US space agency, the 8.9-magnitude quake shifted the way the Earth’s mass is distributed, which made the planet spin a little faster, cutting the 24-hour day by an estimated 1.8 microseconds. That is less than two millionths of one second.
The initial data suggested that the quake moved Japan’s main island about eight feet and shifted the Earth’s figure axis, around which the Earth’s mass is balanced, by about 17 centimetres, said Richard Gross, a geophysicist at NASA’s Jet Propulsion Laboratory in Pasadena, California.
Earlier, scientists have estimated that the quake has shortened the day by 1.6 microseconds.
But the revised estimate — which is based on new data on how much the fault that triggered the earthquake slipped to redistribute the planet’s mass — showed that the day has actually been shortened by 1.8 microseconds, said Gross. Continue reading