Ithaca, NY – At a glacier near the South Pole, earth scientists have found evidence of a slow, slow eruption that triggers strong, slow earthquakes several miles away, according to a Cornell University study published therein Advances in science.
During an earthquake, a rapid slope occurs when energy builds up underground and is quickly released next to a fault. Blocks of ground quickly slide against each other.
However, at the Antarctic glacier known as the Whillans Ice Plain, earth scientists show that “slow slips” span dozens of large-scale 7 earthquakes. “We found that there is almost always a‘ slow slip ’before an earthquake,” said lead author Grace Barcheck, a researcher in Earth and Atmospheric Sciences at Cornell University.
Barcheck said these slow precursors – which occur as far as 20 miles away from the center – are directly involved in the onset of the quake. “These slow ditches are very common,” she said, “and migrate to where the rapid earthquake begins.”
Observations before several major earthquakes generated by magnitudes 8 and 9 on transmission zone faults suggest a similar process could have occurred, according to Patrick Fulton, assistant professor and Sesquicentennial Croll Fellow in Department of Earth and Atmospheric Sciences.
Because these cracks are usually offshore and deep underwater, and because it is difficult to tell when or where a major earthquake will occur, it is usually difficult to see large earthquakes.
To overcome these challenges, the scientists placed GPS sensors over a frozen glacial fault at the Whillans Ice Plain, where magnitude 7 earthquakes occur nearly twice a day over a 60-ice area. -stream of the glacier.
Within two months of 2014, the group captured 75 earthquakes at the base of the Antarctic glacier. Data from GPS stations showed that 73 – or 96% – of the 75 earthquakes showed a period of slow movement beforehand.
The data from the GPS tracking stations and surface seismometers let the team identify how the slow slope triggers a rapid earthquake.
“Our group was amazed to see so many pre-runs,” Barcheck said.
“In some cases, we can actually migrate in advance of the earthquake to where the earthquake begins.”
“Before we looked at the data, I thought if we saw any predators before the earthquakes, they would be rare and in the same place as the epicenter of the quake,” she said. , we found a lot of slow pre – runners – starting miles from the epicenters and migrating over the fault. “
###
In addition to Barcheck and Fulton, co-authors of the research, “Earthquake Migration Dominant Migration from an Ice Stream Fault,” Emily Brodsky, professor, Department of Earth and Planning Sciences, University of California, Santa Cruz, former visiting professor at Cornell; Matt King, professor, Geography and Spatial Sciences, University of Tasmania, Hobart, Tasmania; Matthew Siegfried, Department of Geophysics, Colorado School of Mines, Golden, Colorado; and Slawek Tulaczyk, professor, Department of Earth and Planning Sciences, University of California, Santa Cruz.
Fieldwork and analysis for this research was supported by the National Science Foundation.
Disclaimer: AAAS and EurekAlert! they are not responsible for the accuracy of press releases posted to EurekAlert! by sending institutions or for using any information through the EurekAlert system.