The United States Geological Survey (USGS) linked 114 remote earthquakes to the magnitude 8.6 East Indian Ocean quake that occurred April 11, 2012.
USGS seismologist Fred Pollitz and colleagues published their findings Sept. 26, 2012 in "Nature."
The study focused on global seismic activity triggered by the East Indian Ocean quake, according to a USGS press release.
The scientists found that the magnitude 8.6 earthquake triggered 114 earthquakes that were a magnitude 4.5 or greater in the six days following the quake.
As a result of the findings, the team is redefining the definition of an aftershock. Currently, the term aftershock refers to earthquakes that happen after and nearby the main fault rupture. The new definition will consider aftershocks to be earthquakes of any size and location that would not have taken place had the main shock not struck.
The difference in the two definitions is that an earthquake thousands of miles away can now be called an aftershock of the first earthquake if the seismic activity of the first quake can be determined to have caused the later quake.
After studying the seismic activity after the East Indian Ocean quake, the scientists determined that large earthquakes as far away as Mexico and Japan, in the following days, were actually aftershocks.
The East Indian Ocean was the largest, by a factor of 10, strike-slip earthquake ever recorded. A strike-slip earthquake is caused by two sections of tectonic plates sliding along each other horizontally with very little vertical movement.
"No other recorded earthquake triggered as many large earthquakes elsewhere around the world as this one," said Pollitz.
Remote earthquakes in the six days preceding (top) and the six days following (bottom) the M=8.6 main shock in the East Indian Ocean on April 11, 2012. The color scale indicates seismic stress, with purple = zero and red = high. This graphic is courtesy of USGS.gov.
Travel hazards, delays and disruptions associated with rain, ice and snow will continue over the Central states through the balance of the Thanksgiving weekend.
Following a mild Thanksgiving and Black Friday, noticeably cooler air will return to the Northeast this weekend.
Sandra remains on track to make landfall in northern Mexico on Saturday, but it will be much weaker than its current major hurricane status.
The current reprieve from heavy rain across southern India will not last long with the threat for flooding downpours set to return for the final days of November.
A major Thanksgiving Day storm threatens to ruin holiday events across the Central states with flooding rain, snow, a glaze of ice and fog.
Several days of heavy rain will bring the potential to cause flooding from the southern Plains to the middle Mississippi Valley into early next week.
New England (1888)
Hurricane passed inside Nantucket over Cape Cod. Later crossed Nova Scotia Block Island- 84 mph wind gust.
North Dakota (1896)
Thanksgiving Day Blizzard. "Wind Velocity and snowfall never equalled before."
Destructive windstorm in the Northwest; winds gusting to 105 mph in Cut Bank, MT; 96 mph in Sheridan, WY. Spokane, WA, radio tower downed. Coleville, WA, lumber shed demolished.