For many years, scientists thought there was something strange about East Antarctica. This section of the continent is known as a shield or craton, a very old and stable portion of the continental crust. But unlike other cratons, East Antarctica didn’t seem to experience much in the way of seismic activity. Between 1982 and the early 2000s, just nine earthquakes were recorded in the region.
Experts speculated that the weight of East Antarctica’s ice sheet might be suppressing earthquakes. As it turns out, however, East Antarctica is seismically active—scientists just hadn’t been able to catch all the minor earthquakes that occur there, reports Maddie Stone for Earther.
In 2009, Drexel graduate student (and now assistant professor) Amanda Lough and a team of researchers installed 26 seismic stations in East Antarctica’s icy landscape. As Katherine Ellen Foley of Quartz notes, that’s a lot more than in the past. During previous excursions to East Antarctica, researchers had set up only eight seismic stations. Lough and her colleagues left the seismometers in place until the following year.
When they came to collect the equipment, the researchers found that the seismometers had measured 27 earthquakes in a single year—three times more than had been recorded in the last several decades. Lough and her colleagues recently published the results of their study in the journal Nature Geoscience.
Most of the seismic activity was measured near the Gamburtsev Subglacial Mountains, which is believed to be part of an ancient continental rift system. The earthquakes ranged in size from magnitude 2.1 to 3.9, making them minor events. But the survey revealed that East Antarctica was not a seismic anomaly after all.
“Ultimately, the lack of recorded seismicity wasn’t due to a lack of events but a lack of instruments close enough to record the events,” Lough tells Frank Otto of Drexel Now.
The process of installing the seismometers was extremely difficult, which was why it had not been done before. Lough and her colleagues had to endure Antarctica’s frigid climate and fly from remote point to remote point in planes packed with supplies. Sometimes, they had to dig their own runways for the planes.
The results of their efforts mark the second significant revelation about Antarctica to emerge in recent weeks. Last month, scientists announced that they had discovered massive canyons linking the West Antarctic ice sheet to the East Antarctic ice sheet.
The findings by Lough and her fellow researchers don’t have tremendous implications for the continent’s seismic future; “no one expects East Antarctica to suddenly erupt in seismic activity,” as Quartz’s Foley puts it. But the new study emphasizes how much we have yet to discover about Earth’s southernmost continent.