It’s not every day that students get to swing a sledgehammer in class, but 13 geology majors at California State University, Bakersfield recently did just that. Though the exercise might have had the added benefit of relieving a little school year stress, its main purpose was strictly scientific.
In late March, students in Dr. Matt Herman’s geophysics class had the opportunity to use geophones from SensorEra to conduct seismic refraction imaging. Ten state-of-the-art geophones provided by the company were staked into the ground on the Don Hart East Lawn, each one detecting the motion of the ground when seismic waves pass by. That’s where the sledgehammer came in, with students taking turns to strike a metal plate to induce seismic waves.
“We’re trying to produce a force that sends out a seismic wave significant enough to be picked up by these geophones with a sledgehammer and using all our strength,” said geology major Brooklyn Macross.
Students swung the sledgehammer at a metal plate on the ground, first set on the south side of the lawn, then on the north side. The plate was three feet from the first geophone sensor, with nine more sensors set in a line each 30 feet apart. With about five strikes at a time, the students one by one created forces to gather data that would provide an image of the ground’s subsurface.
“One of the main uses for geophysical techniques is to build images of the subsurface, a place humans typically do not have much access to,” Dr. Herman said, explaining that seismic refraction imaging relies on seismic waves traveling faster in deeper rocks. “This allows us to determine the thickness of layers in the Earth, and the speed of seismic waves through those layers.”
The resulting data like that collected by the students tell geologists about the physical properties of the subsurface, allowing them to interpret in context of the actual rocks underground. The recent seismic refraction exercise is one of many approaches Dr. Herman covers in the class, but the partnership with SensorEra brought this particular technique to life in a new practical way.
Although the Geology Department has older seismic imaging equipment, it no longer works, which led Dr. Herman to seek out opportunities to buy new equipment or collaborate with someone who already has it. Through his collaboration with scientists at California Resources Corporation (CRC), Dr. Herman was connected to SensorEra, a company CRC works with to do its own seismic imaging and earthquake monitoring.
Students got to work with high-tech equipment regularly used to perform surveys in the industry. It was “a glimpse into the life of a professional geophysicist, using cutting edge tools of the trade,” Dr. Herman said.
As Nicholas Brooks from SensorEra put it, the geophones are like “a smart watch for the earth.” Equipped with 4G, GPS and WiFi, the sensor data is streamed to the cloud, with results automatically generated to give geologists a better idea of changes in the Earth beneath their feet.