Money Matters - Simplified

Japan earthquake: Earth's axis tilts, days shorten

According to geophysicists, occurrences like earthquakes, volcanoes, alter the shape of the Earth, and shifts planet's axis.

The massive Japan earthquake has not only caused widespread devastation and thousands of deaths, but it has also jolted Earth's axis into new position and shortened the days.

According to scientists, the Japan tremors were so powerful that they moved the planet’s figure axis, the axis on which Earth’s mass is balanced, by 25cm (10 inches).

Also, the 8.9 magnitude quake sped up Earth's rotation, and shortened days by 1.8 microseconds, stated geophysicist Richard Gross at NASA's Jet Propulsion Laboratory in Pasadena, California.

Scientists added that just after 36 hours of quake, the eastern parts of Japan have moved 12 feet closer to North America, and that Japan has moved downwards about 2 feet.

Quake takes Japan closer to North America
Apart from affecting Earth's rotation and shortening days, the Friday quake, which was the most powerful so far in Japan's recorded history, has also shifted the main island of Japan by 2.5 metres.

The U.S. Geological Survey (USGS) confirmed this information after finding out that a GPS station had moved by more than two meters.

"At this point, we know that one GPS station moved (eight feet), and we have seen a map from GSI (Geospatial Information Authority) in Japan showing the pattern of shift over a large area is consistent with about that much shift of the land mass," said Kenneth Hudnut, a geophysicist with USGS.

Scientists added that just after 36 hours of quake, the eastern parts of Japan have moved 12 feet closer to North America, and that Japan has moved downwards about 2 feet.

Further, the entire earthquake sequence, which included many aftershocks of magnitude 5 or larger, has also altered the shape of the country's coastline.

Explaining the shift
The changes in Earth's rotation and shift in Japan's main island, and eastern parts might startle you, but the findings haven't surprised scientists.

As Japan is on or near to the boundary of four tectonic plates: the Pacific, North American, Eurasian, and Philippines Sea, the earthquake was the result of the movement of these plates which slid by 18 meters.

As a result, there was a redistribution of large amount of planet’s mass, which shifted Earth's axis and and rotation.

"In theory, anything that redistributes the Earth's mass will change the Earth's rotation," stated Gross, adding, “So in principle the smaller aftershocks will also have an effect on the Earth's rotation.”

According to geophysicists, occurrences like earthquakes, volcanoes, alter the shape of the Earth, and shifts planet's axis.

Similar effects of earthquakes in past
To illustrate, the 8.8 magnitude earthquake that hit Haiti last year in January had also shifted Earth's axis by 8 centimeters, or 3 inches. Further, the days had become shorter by 1.26 microseconds.

Even in quake that struck southeast of Sumatra Island, Indonesia in 2004 was so powerful that that it made the planet vibrate on its axis, thus permanently changing the regional map.