The 7.3 magnitude that struck Japan on Friday east of Sendai has experts wondering if it was an aftershock from the massive 9.0 that rocked the nation last year.
U.S. Geological Survey (USGS) geophysicist Jessica Turner says that it is too early to determine if the recent quake is was an aftershock but the earthquake did happen in the "aftershock zone," of the March 2011 Tohoku earthquake.
According to Yahoo scientists say it's quite possible for aftershocks to arrive so late. "It's very normal to have aftershocks more than a year later," Turner told OurAmazingPlanet.
Experts say a huge seismic event like an earthquake can cause aftershocks as the planet looks to adjust itself back to a point of normalcy.
"It's going to take a long time for the Earth to get back to the background level of seismicity after last year's event," she said.
Friday's earthquake has created fresh fears among residents who were afflicted by the last major quake. The epicenter was 152 miles (245 km) southeast of Kamaishi, Japan. It originated 22.4 miles (36.1 km) below the Earth's surface and struck at 5:18 p.m. local time (3:18 a.m. ET).
According to USGS the tremor was caused by reversing faulting, in which the Pacific Plate subducts, or moves underneath the Eurasian plate, Turner said. The plate-boundary region surrounding the site of today's quake hosts moderate to large earthquakes fairly regularly.
Japan had to deal with a massive quake that created a tsunami that wiped out various parts of the Japanese coast. The seismic events killed nearly 20,000 people and caused a nuclear crisis at the Fukushima-Daiichi nuclear plant.
