The Cambrian

Geophysicists poised to size up seismology for Cambrians

Every earthquake reveals more detail about the shifting plates beneath.

That’s the good side of earthquakes: that they allow geophysics researchers to learn more about where the faults in Earth’s crust are and how they are likely to behave. The bad side is that earthquakes throw the humans who live on the surface into chaos.

Geophysicists such as Bruce Julian and Gillian Foulger have made studying the cracks and strains in Earth’s crust their life work. Plate tectonics explains that the surface where we live sits on rocky plates that are granitic on top and denser beneath. Those plates move, creating the mountains and valleys on the surface — and causing earthquakes.

Dr. Julian, who will appear with Dr. Foulger, will talk about their work and answer questions from Cambrians from 3 to 5 p.m. Jan. 10 at the Veterans Memorial Building.

Julian spent most of his 40-year professional career with the U.S. Geological Survey. Foulger teaches and conducts research at Durham University (England) Department of Earth Sciences. Their connection to Cambria is through Don Anderson, who retired to Cambria after his career as a professor of geophysics at California Institute of Technology in Pasadena and director of the Seismological Laboratory there. He earned the highest honors in his field, in the U.S. and internationally, including the National Medal of Science presented to him by President Bill Clinton. Anderson lived in Cambria until his death in 2014. His wife, Nancy, serves on the board of Greenspace.

“He left a great legacy, and very clever, well-trained people to carry on where he left off,” Julian said in an interview in San Francisco, where he attended the American Geophysical Union Fall Meeting in December. Nearly 24,000 geophysicists attended, making it the largest Earth and space science meeting in the world.

Geophysicists study Earth’s physical properties: its shape, gravitational and magnetic fields, what’s going on under the surface and what’s going on in the space that surrounds it. Julian got interested as a student because he liked hiking in the mountains. He wondered why the mountains were there. He changed his major from electrical engineering to geophysics after spending a summer working with Anderson.

“Seismic waves make pictures of what has happened,” he said. “Once you start thinking about the subject, it goes into everything: what’s inside the earth, why is there a magnetic field …”

Those waves can also be used to monitor nuclear explosions, such as the one set off by North Korea in 2006. Julian worked with the Massachusetts Institute of Technology’s team distinguishing between natural earthquakes and explosions. Locations of monitoring equipment were kept secret, to shield the border countries where it’s placed from political repercussions.

“When North Korea did a test, we knew immediately where it was,” Foulger said.

“It’s not a secret project, but it has a secret component,” Julian said.

Most, if not all, seismic equipment for nuclear monitoring is now public and operated by international agencies.

Californians live over a system of faults in the tectonic plates below.

“There are little faults everywhere,” Julian said. “Most Californians should assume that they are living near a fault.”

Despite the years of study, geophysicists can’t predict exactly when and how those faults will slip and cause an earthquake. People have to be prepared for the inevitable.

“As a general principle, be prepared to take care of yourself for a while,” he said.

“Don’t worry too much about being killed,” Foulger said. “A wood-frame house probably won’t kill you.”

Cambria’s emergency teams are prepared for quakes and tsunamis, giant waves caused by undersea earthquakes. Cambria’s Fire Safe Focus Group, which meets from 3 to 5 p.m. on second and fourth Wednesdays of each month at the fire station, is working to help Cambrians be prepared for all emergencies.

Earthquake talk

Geophysicists Bruce Julian and Gillian Foulger will appear from 3 to 5 p.m. Jan. 10 at the Veterans Memorial Building. The event is open to the public for a $10 donation at the door. The visit is sponsored by Greenspace — The Cambria Land Trust. Questions are welcome and may be submitted in advance via email to