Another earthquake

Interesting how Earthquakes act as cross-purposes to Pollution
with regard to the length of a day. A natural balancing act?
Could increased pollution trigger increased earthquakes?
See the two articles below . . .

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Earth’s Days Get Longer, Humans Responsible
By Robert Roy Britt
Senior Science Writer
posted: 12:33 pm ET
12 February 2002

Humans have been accused of polluting the ground, the water, the air, and even the airwaves, according to some. Now, it seems, we’re messing around with time.

A new study shows that industrial pollution, which is thought by many scientists to fuel global warming, may have a remarkable side effect: A warmed atmosphere with stronger winds would slow the Earth down, causing the planet to take just a wee bit longer to make a full rotation on its axis.

The effect, assuming it occurs, would be miniscule, measured in fractions of a second over decades. The bottom line: If you live to be 100, pollutants may buy you an extra 11/100,000 of a second each day in your later years compared with your first year on the planet.

Olivier de Viron of Belgium’s Royal Observatory led the new study, which used computer models to analyze the effect of adding 1 percent more carbon dioxide to the atmosphere each year, a human contribution established in other studies.

While critics dispute climate change data and the role of carbon dioxide, most leading scientists agree that Earth’s climate is being warmed by increased output of this and other so-called greenhouse gases. The idea that a warmed atmosphere would slow Earth’s rotation is not a new one, and it is based on fundamentals of physics.

In an e-mail interview, de Viron explained what the models predict:

Global warming makes the atmosphere rotate faster. “The average wind, which is already faster than the Earth, will go faster,” de Viron said. A principle in physics states that the overall angular momentum of Earth and its atmosphere must be conserved, meaning that when one part increases its rotation, the rotation of another part must decrease to compensate.

“Consequently, the Earth rotates slower, and the day is longer,” de Viron said.

De Viron said it’s impossible to know whether the effect is underway. Many other factors change Earth’s rotation rate in subtle ways from day-to-day and month-to-month. Only with decades of observation would the effect emerge from a sea of other data.

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Chile earthquake may have shortened days
Seventh strongest quake in recorded history may have shifted Earth’s axis
Most viewed on msnbc.com
updated 2 hours, 55 minutes ago

The massive 8.8 earthquake that struck Chile may have changed the entire Earth’s rotation and shortened the length of days on our planet, a NASA scientist said Monday.

The quake, the seventh strongest earthquake in recorded history, hit Chile Saturday and should have shortened the length of an Earth day by 1.26 microseconds (millionths of a second), according to research scientist Richard Gross at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

“Perhaps more impressive is how much the quake shifted Earth’s axis,” NASA officials said in a Monday update.

The computer model used by Gross and his colleagues to determine the effects of the Chile earthquake effect also found that it should have moved Earth’s figure axis by about 3 inches (8 centimeters or 2.7 milliarcseconds).

Earth’s figure axis is not the same as its north-south axis, which it spins around once every day at a speed of about 1,000 mph (1,604 kilometers per hour).

The figure axis is the axis around which Earth’s mass is balanced. It is offset from the Earth’s north-south axis by about 33 feet (10 meters).

Thousands rattle the Earth daily — but only a few cause utter devastation.
Strong earthquakes have altered Earth’s days and its axis in the past. The magnitude-9.1 Sumatran earthquake in 2004, which set off a deadly tsunami, should have shortened Earth’s days by 6.8 microseconds and shifted its axis by about 2.76 inches (7 centimeters, or 2.32 milliarcseconds).

One Earth day is about 24 hours long. Over the course of a year, the length of a day normally changes gradually by one millisecond. It increases in the winter, when Earth rotates more slowly, and decreases in the summer, Gross has said in the past.

The Chile earthquake was much smaller than the Sumatran temblor, but its effects on Earth’s figure axis were a bit larger because of its location. Its epicenter was located in the Earth’s mid-latitudes rather than near the equator like the Sumatran event.

The fault responsible for the 2010 Chile quake also slices through Earth at a steeper angle than the Sumatran quake’s fault, NASA scientists said.

“This makes the Chile fault more effective in moving Earth’s mass vertically and hence more effective in shifting Earth’s figure axis,” NASA officials said.

Gross said his findings are based on early data available on the Chile earthquake. As more information about its characteristics are revealed, his prediction of its effects will likely change.

The Chile earthquake has killed more than 700 people and caused widespread devastation in the South American country.

Several major telescopes in Chile’s Atacama Desert have escaped damage, according to the European Southern Observatory, which manages those facilities.

A salt-measuring NASA satellite instrument destined to be installed on an Argentinean satellite was also undamaged in the earthquake, JPL officials said.

The Aquarius instrument was in the city of Bariloche, Argentina, where it is being installed in the Satelite de Aplicaciones Cientificas (SAC-D) satellite. The satellite integration facility is about 365 miles (588 km) from the Chile quake’s epicenter.

The Aquarius instrument is designed to provide monthly global maps of the ocean’s salt concentration in order to track current circulation and its role in climate change.