Chilean Earthquake May Have Shortened the Length of a Day on Earth

This view of Earth comes from NASA's Moderate Resolution Imaging Spectroradiometer aboard the Terra satellite.


Yikes! Just how big was the magnitude 8.8 earth quake in Chile? One scientist says the shaking may have affected the entire planet by shifting Earth on its axis. This possibly may have shortened the length of a day on Earth by about 1.26 microseconds. Using a complex model JPL research scientist Richard Gross computed how Earth’s rotation should have changed as a result of the Feb. 27, 2010 quake. If his figures are correct, the quake should have moved Earth’s figure axis (the axis about which Earth’s mass is balanced) by 2.7 milliarcseconds (about 8 centimeters, or 3 inches).

Earth’s figure axis is not the same as its north-south axis; they are offset by about 10 meters (about 33 feet). By comparison, Gross said the same model estimated the 2004 magnitude 9.1 Sumatran earthquake should have shortened the length of day by 6.8 microseconds and shifted Earth’s axis by 2.32 milliarcseconds (about 7 centimeters, or 2.76 inches).

Gross said that 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.

Gross said the Chile predictions will likely change as data on the quake are further refined.

Source: JPL

8.8 Magnitude Earthquake in Chile; Tsunamis Predicted for Pacific Region

Map showing regions likely to be hit by tsunamis following 8.8 earthquake in Chile. Credit: NOAA

A devastating magnitude-8.8 earthquake struck Chile early Saturday, shattering buildings and bridges, killing over 100 people and setting off a tsunami that threatens every nation around the Pacific Ocean — roughly a quarter of the globe. Experts warned that a tsunami could strike anywhere in the Pacific, and Hawaii could face its biggest tsunami since 1964. The Pacific Tsunami Warning Center predicts a possible 2.5 meter (8.2-foot) wave to strike Hilo, Hawaii, at 11:05 a.m. local time (4:05 p.m. ET).

The National Weather Service has issued a tsunami warning for the entire West Coast of the US, and is advising everyone in coastal counties to stay away from beaches and shorelines this afternoon when a tsunami producing strong currents and a series of potentially dangerous waves is expected to hit the coast at around 1:20 p.m PST.

Alaska is also threatened, and tsunami waves could possibly hit Asian, Australian and New Zealand shores within 24 hours of the earth quake. See the map above of the tsunami predicted paths.

Map of Chile. Credit: USGS

The quake struck at 3:34 a.m. (1:34 a.m. EST, 0634 GMT) 200 miles (325 kilometers) southwest of Santiago.

Chilean TV showed devastating images of the most powerful quake to hit the country in a half-century: In the second city of Concepcion trucks plunged into the fractured earth, homes fell, bridges collapsed and buildings were engulfed in flames. Injured people lay in the streets or on stretchers.

Many roads were destroyed and electricity and water were cut to many areas.

Several astronomical observatories are located in Chile, and as of this writing, the word on Twitter is that Gemini South’s servers have come back online, but Cerro Tololo (CTIO) and SLOOH servers are down. No word on telescopes yet at Paranal, which is north of Santiago, Chile. From the ALMA crew at NRAO, “Reports from our people in Santiago are trickling in; so far everyone is ok, but quite rattled.”

Links of interest:
NOAA Pacific Tsunami Warning Center

Live streaming news from Hawaii

Estimated arrival times for tsunamis.