Oct. 21, 2015

Students deploy seismometers to gain underground view

Seismometers in ground
Jason Koski/University Photography
Fabio Guilhon '16, left, and assistant professor Katie Keranen examine an iPhone compass to determine how to place the seismometer in the proper direction.
Diego Quiros
Jason Koski/University Photography
Doctoral student Diego Quiros shows undergrads how to test equipment before burying it underground.
Larry Brown
Jason Koski/University Photography
Professor Larry Brown, left, and civil engineering doctoral candidate Brad Wham assemble a temporary solar panel that will provide energy for the seismometer system.

Cornell undergraduate students from a geophysics class will deploy a network of 15 seismometers around campus through late fall, through which they will collect data for a year.

In the Intraplate Tectonics Monitoring Project, Cornell geologists will obtain an accurate picture of what lies beneath. This project – which uses campus as a living laboratory in the Exploration Geophysics class taught by Larry Brown, the Sidney Kaufman Professor in Geophysics, and Katie Keranen, assistant professor of earth and atmospheric sciences – will assess background-level seismicity near campus to gain a long-term understanding of low-level seismic activity in the northeastern United States.

Further, this project will provide digital upgrades to the long-running paper seismographs in Snee Hall, which will allow students, faculty and the public to connect to an online real-time “feed” of seismic activity around the world.

The Exploration Geophysics course offers an introduction to theory and practice, which includes geophysical field methods such as gravity, electromagnetics, seismology and ground-penetrating radar. Students apply these methods by conducting surveys and analyzing data.

“In this experiential project, the students will be exposed to a wide range of geophysical techniques. They’ll learn how to analyze such data to gain an appreciation of how it can help to find subsurface resources such as water, minerals, oil and gas,” said Brown. “They’ll learn to process vibrational noise to define the distribution and properties of different layers of rocks, and they’ll discern waves from distant earthquakes to ‘see’ the structure of the Earth down to the base of the crust – and deeper.”

Although similar to the national-scale EarthScope project, which has transported a seismic array across the contiguous United States and into Alaska, this project will concentrate on the campus and Ithaca area.

“With the EarthScope Transportable Array, we learned things we didn’t expect,” explained Keranen, who is co-teaching this class for the first time. “With this array, we may find things locally of which we weren’t aware.”

The seismometer stations consist of the seismometer itself, which samples ground vibrations at 250 cycles per second at intermediate wave frequencies, a power supply and a small solar panel to charge a battery. Students will bury the seismometer and power supply in shallow pits in the ground, with only the solar panel visible at the surface.

On a beautiful autumnal day in mid-October, Brown, Keranen and teaching assistant Diego Quiros, a doctoral candidate in the field of geology, taught the undergraduates how to install a seismometer station. After operating for a year, the station will be removed and the holes filled in.

Expenses associated with deploying the seismometer network were funded by Cornell’s Atkinson Center for a Sustainable Future. The seismometers are on loan from the national IRIS-PASSCAL instrument center.