14 DAY TRIAL // Soon after the Saturday, February 27 earthquake that struck Chile with a magnitude of 8.8 degrees, experts at the NASA Jet Propulsion Laboratory (JPL), in Pasadena, California, began working on a model to determine how the tremor influenced the planet. Their preliminary, rough results show that the ground-shake caused the length of each day to decrease slightly, and also that the planet's axis was knocked slightly off-course. All strong earthquake can cause such reactions, but the amount of change their produce various widely with depth, fault line type, latitude and so on, the team reports.
Expert Richard Gross, who is a research scientist at the California Institute of Technology (Caltech) laboratory, developed a rough computer model to determine how the tremor affected the planet. He explains that the length of each day on Earth has been shortened by about 1.26 microseconds. The time that is lost from now on is due to the fact that the planetary figure axis is now moved by about 8 centimeters, or 3 inches, from the position it had before the devastation. The expert explains that the figure axis is not one and the same as the north-south axis. The two are separated by a small distance, of roughly 10 meters (about 33 feet).
A similar shift in the length of days was also recorded during the Sumatran earthquake of 2004, which had a magnitude of 9.1 degrees and sent a devastating tsunami across the ocean surface. That seismic event apparently shortened days by about 6.8 microseconds and additionally shifted the axis by around 7 centimeters, or 2.76 inches. Gross says that the new results will most likely be refined even further, as additional data from satellites and ground measurements become available for implementation in his model.
“[...] even though the Chilean earthquake is much smaller than the Sumatran quake, it is predicted to have changed the position of the figure axis by a bit more for two reasons. First, unlike the 2004 Sumatran earthquake, which was located near the equator, the 2010 Chilean earthquake was located in Earth's mid-latitudes, which makes it more effective in shifting Earth's figure axis. Second, the fault responsible for the 2010 Chiliean earthquake dips into Earth at a slightly steeper angle than does the fault responsible for the 2004 Sumatran earthquake. This makes the Chile fault more effective in moving Earth's mass vertically and hence more effective in shifting Earth's figure axis,” JPL experts say.