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

Chilean Telescopes OK, ESO, Gemini Report

The ESO Very Large Array atop Cerro Paranal, northern Chile (ESO).


The European Southern Observatory, which has several telescopes housed in the mountains of Chile, issued a press release that none of the observatories suffered any damage, and they have no reports of any staff that were injured or killed in the magnitutde 8.8 earthquake that struck central Chile on February 27, 2010:

Despite being the 7th strongest earthquake ever recorded worldwide, the ESO observatory sites did not suffer any damage, partly as they are engineered to withstand seismic activity and partly due to their distances from the epicentre. At La Silla, a power cut caused observations to stop during the night. Paranal Observatory, the APEX telescope and the ALMA Operations Support Facility and Array Operations Site were unaffected.

Additionally, the Gemini South Observatory posted on their website that they experienced no significant damage:

Sunset over Gemini South. Credit: Gemini

Gemini was fortunate that there were no significant structural damages to any of our facilities. The earthquake disrupted observations on early Saturday morning for less than 30 minutes. Subsequent operations have been essentially normal with the exception of Internet connectivity. We are dealing with communications and minor power inconsistencies that should be solved once general Chilean infrastructure issues are resolved. The temblor struck about 700 kilometers south of Gemini South which is on Cerro Pachón.

ESO reported that they are experiencing power outages and network interruptions, which means that communication may be limited. “Disruption to staff travel plans within, to, and from Chile should be expected. We urge Visiting Astronomers with observations planned at ESO observatories to put their trips to Chile on hold until further notice. International flights to and from Santiago International Airport are currently either cancelled or diverted. Information about observing programmes will be provided at a later date,” the press release said.

Other observatories in Chile include Cerro Tololo (CTIO) and SLOOH. The servers for the websites for these observatories were down on Saturday, but are now back up.

The SLOOH Twitter account reported late Sunday that their observatory has no power but scope, pier and dome appear to be OK. “Won’t know more until power is restored,” they said.

Update (3/1/2010): Mark T. Adams from NRAO sent this report via Facebook (thanks to Richard Drumm for forwarding it on to UT!):

“We’ve been able to contact or have heard from most of our staff based in or visiting Chile, and we are relieved to report that there appear to be no injuries to our staff or their families. Communication remains very difficult: land-lines, cell-phones, and the Internet are intermittent and unreliable.

“The ALMA Array Operations Site and Operations … See MoreSupport Facilities in northern Chile suffered no damage other than loss of communications. It may take a few days for the completion of a safety inspection of the NRAO/AUI and JAO offices in Santiago, which suffered some damage.”

The earthquake epicentre was 115 km north-northeast of the city of Concepción and 325 km south-west of the capital Santiago. The earthquake caused significant casualties and damage in the country.

Source: ESO, Gemini South

Why Was the February 27, 2010 Tsunami Smaller than Expected?

Chart of the Chile tsunami's travel time, released by the National Atmospheric and Oceanic Administration. Photograph: AFP/Getty Images

While a huge earthquake off the coast of Chile triggered a tsunami that moved at the speed of a jet aircraft across the Pacific Ocean on Feb. 27, the tsunami event – thankfully — was smaller than scientists expected. Some experts forecasted the event would produce 9-foot tall tsunami waves slamming coastlines along the Pacific Rim, which did not materialize; it would have been one of the biggest tsunami on record. At magnitude 8.8, this earthquake was among the largest seismic activity ever recorded. So, why was the resulting tsunami not a “mega event” as well?

“It is too early to know for sure,” said Anne Sheehan, a geologist from the University of Colorado – Boulder.

“It was a truly enormous “megathrust” earthquake, shallow and offshore,” Sheehan told Universe Today. “That kind of earthquake can generate a large tsunami if it displaces a large area of seafloor vertically (either up or down). It could be that more of the earthquake displacement was at depth below the seafloor, and did not rupture the seafloor surface as much as was expected given the size and depth of the earthquake.”

Sheehan said the Chilean earthquake released more than 400 times the energy of the recent Haiti earthquake. “It was truly an enormous earthquake in terms of energy release, the largest in the world since the 2004 Sumatra earthquake and the fifth largest since 1900,” she said.

The earthquake that generated the great Indian Ocean tsunami of 2004 is estimated to have released the energy of 23,000 Hiroshima-type atomic bombs, according to the U.S. Geological Survey (USGS).
The 8.8 quake in Chile released the energy equivalent of 20 billion tons of TNT, or 400 times the largest nuclear weapon ever detonated, the Tsar Bomba, a 50 megaton test done by the USSR in 1961.

A tsunami warning buoy was deployed by the Chilean Navy and WHOI off the northern coast of Chile in December 2004 as part of a national warning system west of Chile. (Photo by Robert Weller, WHOI)

Chile is along the “Ring of Fire” that stretches north from South America to the Aleutian Islands, then south through Japan, Indonesia and to New Zealand. The fault zone of the Chilean earthquake was extremely long — several hundred miles — signaling the potential for further large earthquakes in the region.

“These large earthquakes in the Southern Hemisphere have the potential to cause tsunamis all over the Pacific Rim,” Sheehan said in a press release. “Fortunately, people have a much greater understanding of the phenomenon today. Before 2004, a lot of people didn’t even know what a tsunami was,” she said.

Sheehan said she believes that lessons learned by Chilean experts following a world-recording setting magnitude 9.5 quake there in 1960, and subsequent quakes in the next several decades, resulted in stricter building codes, saving many lives. “The death toll is expected to be far smaller than in Haiti, an example showing that mitigation efforts really can be effective.”

As of this writing, the death toll stands of the Chile earthquake stands at 711. The quake in Haiti killed over 200,000 people.

Early earthquake picture posted on Twitter by @tapeks.

Lessons learned from the 2004 Indian Ocean event also allowed officials to send out effective early warnings and initiate the evacuation of tens of thousands of people living on Pacific islands. Now, even more is being learned about the nature of tsunamis from this latest event, and future predictions should improve.

Sources: Email interview with Anne Sheehan, CU-Boulder press release

ISS Astronaut Sends Twitpics of Chile Earthquake Aftermath

Santiago, the capital city of Chile. One day after the Mega earthquake(M8.8) hit the country. We wish the earliest recovery. Credit: Soichi Noguchi

Astronaut Soichi Noguchi, (@Astro_Soichi) who has taken full advantage of being able to use Twitter live from the International Space Station, has been sending down a stream of images he has taken of Chile following the magnitude 8.8 earthquake that hit the country early Saturday. Just recently, he posted the above image, taken directly over Santiago. “Santiago, the capital city of Chile. One day after the Mega earthquake(M8.8) hit the country. We wish the earliest recovery,” Noguchi wrote on Twitter. He also took a video of the ISS astronaut’s view as they flew over Chile earlier today, below.

Here’s another image Noguchi took from the ISS, of the coastline of Chile, near Santiago.

Near Santiago, Chile. Coast line. Credit: Soichi Noguchi

And another, near Concepcion, Chile.

Coastline near Concepcion, Chile. Credit: Soichi Noguchi

For more images from space, follow @Astro_Soichi on Twitter.

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.