San Bernardino

When the Ground Shakes, CSUSB Alumnus Seeks to Find Out Why




​​After the largest temblor in 20 years hit the Golden State last July, Bryan Castillo (MS, Earth and Environmental Sciences, ’19) spent two days in the desert. 

The Cal State San Bernardino (CSUSB) department of geological sciences alumnus has studied earthquakes for years—his master’s thesis was on a portion of the San Andreas Fault—but the big shake-ups were his first chance to study the aftermath of one in the field. Castillo was among several geologists, students, researchers, and others from across the nation who investigated the damage caused by the 2019 quakes and collected data near two desert communities along Highway 178. 

The July 4 and July 5 earthquakes were centered near Ridgecrest and the nearby town of Trona. The quakes’ magnitudes were measured at 6.4 and 7.1, respectively. The quakes cracked walls, damaged structures, and interrupted services such as water and electricity. 

Castillo’s interest in geological sciences was sparked after the 2008 Chino Hills earthquake (magnitude 5.4) struck. He was a high school student in Los Angeles at the time. 

“To get a chance to see the surface rupture of an earthquake is beyond exciting for me,” Castillo said. “I had to take advantage of it.” 

While at Highway 178, Castillo and others took measurements, mapped the area, and took photos to gather valuable information. The data is shared with the California Earthquake Clearinghouse, a volunteer-run effort to “coordinate earthquake field investigations and share observations and knowledge among emergency responders, engineers and scientists,” according to the clearinghouse’s website. 

​The researchers saw ruptures along the surface of the ground and highway, small fissures, sand blows—formed from the eruption of water and sand to the ground surface—and other characteristic aftereffects. They also saw a displaced fence near the Naval Air Weapons Station China Lake, a military installation and a set of railroad tracks that had been warped. 

Castillo also worked with world-renowned geophysicist Dr. Roger Bilham of the University of Colorado Boulder to study the area. He helped set up creepmeters (instruments that measure the slow movement of fault lines) along the earthquake rupture and other nearby faults and repeatedly returned to the area to collect the data. Castillo and Dr. Bilham subsequently published their findings—Castillo’s first-co-authored paper—this past January in Seismological Research Letters. 

“Bryan has taken advantage of every opportunity to further his education and career, including graduate thesis grants from the Office of Student Research, presenting his work at local, regional and national meetings, assisting with the field work of other graduate students, and volunteering to tell his story at outreach events,” said Dr. Sally McGill, a geologist and the associate dean for the College of Natural Sciences. “His recent work with Dr. Roger Bilham measuring fault creep after the Ridgecrest earthquakes is further expanding his research experience and connections to the scientific community.” 

Castillo has continued to distinguish his academic credentials. His M.S. thesis on the timing of prehistoric earthquakes on the Banning strand of the San Andreas fault is in the final stages of peer review for publication in the journal Geosphere. Last year, he began serving as a part-time lecturer for the department of geological sciences, and is currently a part-time instructor at Crafton Hills College. Last November, Castillo was named the 2018-2019 recipient of a CSUSB Office of Graduate Studies Outstanding Thesis Award for research documenting eight prehistoric earthquakes in the past 7,000 years that “broke new ground in the field of earthquake geology.” He also recently launched, with a partner, an earthquake consulting business to apply his scientific training to help educate and prepare consumers for temblors.