Undersea volcanoes are just fine, and so kind compared to studying the ones above the surface. The Axial Seamount 300 miles off the Oregon Coast is sure proving to be a good laboratory to study volcanoes lately. Conveniently not too far offshore, Axial Seamount is frequently active, not particularly hazardous to people, and has a relatively simple subsurface structure. Three papers published in Science and Geophysical Research Letters describe some of the volcano’s recent goings-on.
The active undersea volcano erupted in 1998, 2011, and again in 2015. That last one was predicted months in advance by Oregon State University geology and geophysics professor Bill Chadwick — also with NOAA’s Pacific Marine Environmental Laboratory, along with University of North Carolina Wilmington geology professor Scott Nooner.
“Because Axial is on very thin ocean crust, its ‘plumbing system’ is simpler than at most volcanoes on land that are often complicated by other factors related to having a thicker crust,” said Chadwick, back before the last eruption in an OSU press release by Mark Floyd in April 2015. “Thus Axial can give us insights into how volcano magma systems work – and how eruptions might be predicted.”
Chadwick is co-author of two out of three of the recent peer-reviewed papers. “Ironically, in some ways we can learn more about how volcanoes work by studying them underwater because the seismic imaging works so much better in the oceans,” Chadwick said to Floyd in a December 2016 press release. “Previous surveys created the images of where the magma is and because ships can go everywhere over the volcano we get a lot more data. On land, you have to drill a hole, set off an explosion, and record it with a few scattered seismometers. It’s not nearly as effective.”
“We’re beginning to really understand how this volcano works and some of these lessons can be applied to other volcanoes in a general way,” said Chadwick. “During its eruptions, Axial’s seafloor drops suddenly by about eight feet, and then over the next several years it gradually rises back up. When it re-inflates to a certain level, the volcano is almost ready to erupt again.”
It inflates with magma and not air, though, so hurray for submerged off-shore science. “Now we’ll just have to watch and see how fast it builds back up,” Chadwick said. “We’ll be trying to forecast the next eruption again, but right now it’s a little too early to tell.”
By Matthew Hunt