PROVIDENCE, R.I. [Brown University] — With the help of a National Science Foundation grant, Brown University geophysicist Colleen Dalton is making a seismic sonogram of the crust and mantle deep beneath the surface of North America.
Dalton, an assistant professor of Earth, environmental and planetary sciences, uses seismic waves generated by earthquakes to probe the properties of the Earth’s interior. The characteristics of seismic waves — their speed and rate of decay — change as the waves travel through different types of rocks. Dalton can make inferences about different geologic units — their chemical composition, temperature and whether volatile compounds like water are present in them — by measuring how they transmit seismic waves.
With the support of a CAREER Award, NSF’s most prestigious award for early career faculty, Dalton will use this seismic wave technique to map out the physical and chemical properties of the subsurface U.S. She will receive $521,402 over five years to perform the work.
“North America, and the U.S. in particular, presents an amazing opportunity to do a study like this because the continent has this incredibly diverse geologic history,” Dalton said. “There are mountains and volcanoes in the west, vast plains in the middle and the Appalachian hills to the east. These interesting features at the surface have an equally interesting story beneath the surface. That’s what we want to probe.”
The landforms we see in the U.S. today are the result of billions of years of tectonic activity — numerous episodes of continental breakup, collision and modification. Those tectonic processes are driven by the slow churning of rocks in the mantle.
“We want to gain a better understanding of how what we see at the surface is linked to the physical and chemical properties of the crust and mantle below,” Dalton said.
The grant includes an education and outreach component, and undergraduates from Brown and elsewhere will have the chance to work on the project in Dalton’s lab. Dalton will also install educational seismometers at local high schools so students can monitor earthquake activity around the world in real time. She will also work with teachers to develop new Earth science teaching materials.
“Earth science occupies a prominent spot in Next Generation Science Standards being rolled out across the country,” Dalton said. “So this is a great time to be developing lesson plans and teaching modules that can be distributed to schools around Rhode Island and beyond.”