Virginia Tech seismologist gets to the core of historic West Coast earthquake
In the heart of the Blue Ridge Mountains, Virginia Tech researcher Tina Dura and her lab are making waves on the West Coast.
“What separates these seismologists from other earthquake scientists is that they are looking for tiny fossilized algae in the sediment,” said Jes Burns, host of Oregon Public Broadcasting program “All Science. No Fiction,” during a recent episode.
The broadcast, which aired in late June, spotlighted the Virginia Tech team’s work taking core samples from Oregon’s coastal marshes. Burns followed the researchers as they examined the sediment and fossilized algae – called diatoms – to help reconstruct the seismic history of the Cascadia subduction zone, which spans 1,300 kilometers from Vancouver Island, Canada, to Mendocina, California.
For Dura, assistant professor of geosciences and head of the Virginia Tech Coastal Hazards Lab, the episode was the latest highlight of their work aimed to better understand earthquakes and tsunamis of the past and better prepare for the future.
“I love being able to unravel earthquake and tsunami histories by reading the clues left behind in coastal sediment, and it’s encouraging when other people find it interesting too,” said Dura, who is an affiliate with the Fralin Life Science’s Global Change Center. “At the end of the day, we are trying to increase public awareness of the earthquake and tsunami threat to coastal communities, so the more that information is out there in different forms - publications, public lectures, media - the better.”
The group uses geologic methods to reconstruct the seismic history of the United States’ Northwest Coast to better understand these past disasters and help gauge the potential of future ones. Its researchers have conducted and published National Science Foundation (NSF) sponsored research, and Dura is playing a key role in the establishment of the Cascadia Region Earthquake Science Center and its planned open-access databases.
Bolstered by a $250,000 grant from the NSF, the researchers are focused on mapping out the geophysical rupture and ensuing tsunami inundation from the Cascadia subduction zone’s last known earthquake in 1700. Dura's research peers at the University of North Carolina, Wilmington, and the University of Oregon were also recipients of the grant.
“We’re starting with the 1700 earthquake because that’s where we have the most data, and then once we refine our technique we can look at older earthquakes,” Dura said.
Other subduction zones in the world have been more active, producing the largest magnitude earthquakes on earth, including a 9.1 to 9.2 in Indonesia in 2004 and a 9.0 to 9.1 in Japan in 2011.
By looking for not only sand, but also for microfossils preserved in the coastal core samples, Dura and the team are discovering the earthquake-induced tsunami to have traveled further inland than previously thought.
“We’re also using the diatoms because they are silt sized, and they get carried much further inland than the sand,” Dura said. “We’ve moved the inundation line inland by about 2 kilometers at one site already.”
Working backward from the inundation will help confine parameters to determine what type of rupture occurred and the magnitude of the quake. Dura and her team will map out the many sites where they have established more precise inundation lines from their grain size and microfossil analyses for a more comprehensive layout of the tsunami and flooding impact.
They plan to share their data with local partners, such as state geological surveys and emergency planners. They also expect to partner with the Shoalwater Bay Indian Tribe in Southern Washington on outreach opportunities.
“We’re also working on collaborating with the Shoalwater Tribe in southern Washington to install informational scientific storyboards around their new vertical tsunami evacuation tower. This is a community that will have very little time to evacuate before a tsunami hits, so it’s important for the population to be informed of what to do following an earthquake,” Dura said.
The research conducted by Dura and her team will complement the her National Science Foundation sponsored research with the Cascadia Region Earthquake Science Center, for which she was awarded $650,000 to develop open-access databases, and direct a summer field school for underrepresented students.
